Showing papers by "University of Texas Medical Branch published in 1989"

A comparison of conservative versus early excision. Therapies in severely burned patients.

Abstract: Early excision and grafting of small burn wounds is a generally accepted treatment. Early excision of burn injuries greater than 30% total body surface area (TBSA) in adults, however, has not been universally accepted. In this study, 85 patients whose ages ranged from 17 to 55 years with greater than 30% total body surface area (TBSA) burns were randomly assigned to either early excision or topical antimicrobial therapy and skin grafting after spontaneous eschar separation. Mortality from burns without inhalation injury was significantly decreased by early excision from 45% to 9% in patients who were 17 to 30 years of age (p less than 0.025). No differences in mortality could be demonstrated between therapies in adult patients older than 30 years of age or with a concomitant inhalation injury. Children (n = 259) with similar large burns treated by early excision showed a significant increase in mortality with increasing burn size and with concomitant inhalation injury (p less than 0.05). The mean length of hospital stay of survivors was less than one day per per cent of TBSA burn in both children and adults.

Increased mortality with intravenous supplemental feeding in severely burned patients.

Abstract: Patients with large cutaneous burns are characterized by an elevated metabolic rate and lose up to 25% of their body weight within 3 weeks. A previous study suggested that intravenous supplementation to attain nutritional requirements was of no benefit in patients with cutaneous burns covering greater than 50% of their total body surface area. In this study 39 patients with burns greater than 50% of their total body surface area were randomly assigned to receive intravenous supplementation of enteral calories (n = 16) or enteral calories alone (n = 23). Intravenous supplementation decreased the amount of enteral calories that patients with burns could tolerate. The mortality rate was significantly higher (p less than 0.05) in the intravenously supplemented group at 63% as compared with 26% in the group receiving enteral calories alone. Both groups showed significant decrease in natural killer cell activity when compared with controls at both 0 to 7 and 7 to 14 days after injury. T cell helper/suppressor ratios were depressed in both groups when compared with controls; however, the intravenously supplemented group was significantly depressed at 7 to 14 days after burn. Both groups demonstrated hepatomegaly, moderate fatty infiltration, and cholestasis. It is suggested that intravenous supplementation should be carefully evaluated and used only in patients with total enteral failure.

Differentiation Between Septic and Postburn Insulin Resistance

Abstract: Sepsis and extensive burn injury produce clinical syndromes characterized in part by "insulin resistance," but it is unclear if these insulin resistant states are identical. To test if the maximal biological effectiveness of insulin is altered in septic or burned patients, eight septic patients and eight nonseptic patients recovering from severe burn injury were studied using the hyperinsulinemic eukalemic euglycemic clamp technique. Compared with bed-rested controls, the septic patients showed an insulin-induced plasma clearance of potassium, which was 183% higher (P less than .001), and a concomitant glucose clearance, which was 52% lower (P less than .001). Nonseptic burn patients also had a 91% increase in potassium clearance (P less than .05), but their maximal insulin-stimulated glucose uptake was not different from that of bedrested controls. When septic patients were compared with their nonseptic burned counterparts, there was no difference in potassium clearance in response to insulin, but glucose uptake by the septic patients was 47% lower (P less than .001). Insulin infusion completely suppressed hepatic glucose production in both septic patients and in nonseptic burn patients. The percent of whole body glucose uptake that was oxidized was not different between the septic patients and the nonseptic postburn patients in both the basal and insulin-stimulated states (38% and 51% v 38% and 42%, respectively). It is concluded that septic and postburn insulin resistance differ in that peripheral glucose uptake in sepsis, but not nonseptic burn injury, is refractory to pharmacologic insulin stimulation, whereas in both states insulin effectively stimulates potassium uptake.

Determinants of head injury mortality: importance of the low risk patient

Abstract: Data were obtained prospectively for 7,912 head-injured patients admitted from 1980 to 1981 to 41 hospitals in 3 U.S. metropolitan areas. Highly significant independent predictors of mortality were motor score, number of reactive eyes, systolic blood pressure, abdominal injury, chest injury, age, and hospital unit (hospital or group of hospitals). The difference between the number of deaths observed and the number expected, by hospital unit, ranged from 43% below expectation to 52% above expectation. The 2 hospital units with the lowest mortality had only 1 death, where 9.4 would be expected, in patients whose risk of death was estimated to be less than 10%. In the single hospital with clearly excess mortality, however, the standardized mortality ratios were 208, 135, and 144% for the risk groups whose probabilities of death were 0 to 50, 50 to 80, and 80 to 100%, respectively. The lack of deaths in those hospitals with the best mortality experience and the excess mortality in the hospital with the worst mortality experience appear to be explained largely by differences in patients who, by clinical criteria, seem to be at low risk for death, and not by severely injured patients.

Structure and Function of the Red Blood Cell Anion Transport Protein

Abstract: PHYSIOLOGICAL FUNCTION . Role of Chloride-Bicarbonate Exchange in Carbon Dioxide Transport .. Other Substrates of Red Cell Band 3 . . Transport Functions Other Than Anion Exchange . . Band 3 Homologs in Nonerythroid Cells ..

School Promotion of Healthful Diet and Physical Activity: Impact on Learning Outcomes and Self-Reported Behavior:

Abstract: The Go For Health Program included classroom health education and environmental changes in school lunch and physical education to foster healthful diet and exercise among elementary school children. Interventions were based on social learning theory and implementation was based on an organizational change strategy for school innovations. Two schools were assigned to intervention and two to control conditions. Cognitive measures (behavioral capability, self-efficacy, behavioral expectations) and self-reported diet and exercise behavior were assessed at baseline and following intervention. Data were analyzed by ANOVA using the student and then the school as the unit of analysis. Statistically significant changes were observed for diet behavioral capability, self-efficacy, and behavioral expectations, use of salt, and exercise behavioral capability (fourth grade), self-efficacy (fourth grade) and frequency of participation in aerobic activity. The results provide evidence for program impact on learning outcomes and student behavior.

Antibiotic beads in the management of surgical infections.

Abstract: Polymethyl methacrylate antibiotic beads have been used successfully in the treatment of surgical infections. Presented are their mechanism of action, their use in experimental and clinical settings, and their complications.

Clinical significance of gastrin receptors in human colon cancers.

Abstract: We have measured gastrin receptors (GR) in surgical specimens from 67 patients with primary colon cancers in order to determine the clinical significance of GR in colon cancer. GR analysis was performed on these specimens, and 22 cancers (32.8%) had no detectable GR. Thirty-eight cancers (56.7%) had high-affinity (Kd less than 1.0 nM) levels of GR. Seven cancers (10.4%) had only low-affinity GR (Kd greater than 1.0 nM). Twenty patients (29.9%) had cancers with GR greater than 10 fmol/mg protein. Mean GR content was significantly greater (11.8 +/- 2.9 fmol/mg protein) in Dukes' Stage A and B cancers when compared to Stage C and D cancers (6.2 +/- 1.6 fmol/mg protein). A significantly greater percentage (52.4%) of patients in the early stages (A and B) had tumors with greater than 10 fmol/mg protein compared to patients with more advanced (C and D) cancers (19.6%). GR content did not correlate with histological differentiation, patient age, or preoperative carcinoembryonic antigen levels. No difference in the GR content was noted between left and right colon cancers or in patients of different sex or race. GR content of normal colon mucosa correlated with the GR content of colon cancers from the same surgical specimen, suggesting that these tumors maintain their normal complement of GR. In the early period of follow-up, 12 of 43 (28%) Stage C and D patients with GR less than 10 fmol/mg protein have died, whereas all 8 Stage C and D patients with GR greater than 10 fmol/mg protein are alive. GR content of colon cancers may have prognostic significance and may identify a group of patients with colon cancer that may benefit from hormonal therapy with antigastrin drugs.

Joint attention and infant toy exploration: effects of Down syndrome and prematurity.

Abstract: 12-month-old infants with Down syndrome (n = 14) and mental and motor age-matched high-risk preterm infants (n = 14) were studied with respect to their ability to attend to and explore their environment in interactions with their mothers. The effectiveness of particular maternal attention-directing techniques in modifying infant responses to toys was expected to vary across the 2 infant groups. In general, higher-level responses to toys were expected to be associated with mother's attempts to maintain rather than redirect the child's attention and the mother's use of structured verbal and nonverbal attention-directing techniques. Results indicated that mothers of the 2 groups of infants used different attention-directing strategies, and their use of particular strategies was differentially related to the attentional capacity of the 2 groups. Differences in the infants' responses to particular maternal strategies were related to the amount of structure provided and to the demands placed on their capacity to shift attention between objects. Fewer specific maternal techniques for directing attention elicited higher-level play behavior from the Down syndrome infants, compared to the preterm group.

Evolutionary conservation of protein regions in the protonmotive cytochrome b and their possible roles in redox catalysis.

Abstract: The amino acid sequences of the protonmotive cytochromeb from seven representative and phylogenetically diverse species have been compared to identify protein regions or segments that are conserved during evolution. The sequences analyzed included both prokaryotic and eukaryotic examples as well as mitochondrial cytochromeb and chloroplastb 6 proteins. The principal conclusion from these analyses is that there are five protein regions-each comprising about 20 amino acid residues—that are consistently conserved during evolution. These domains are evident despite the low density of invariant residues. The two most highly conserved regions, spanning approximately consensus residues 130–150 and 270–290, are located in extramembrane loops and are hypothesized to constitute part of the Qo reaction center. The intramembrane, hydrophobic protein regions containing the heme-ligating histidines are also conserved during evolution. It was found, however, that the conservation of the protein segments extramembrane to the histidine residues ligating the low potential b566 heme group showed a higher degree of sequence conservation. The location of these conserved regions suggests that these extramembrane segments are also involved in forming the Qo reaction center. A protein segment putatively constituting a portion of the Qi reaction center, located approximately in the region spanned by consensus residues 20–40, is conserved in species as divergent as mouse andRhodobacter. This region of the protein shows substantially less sequence conservation in the chloroplast cytochromeb 6. The catalytic role of these conserved regions is strongly supported by locations of residues that are altered in mutants resistant to inhibitors of cytochromeb electron transport.

Closed head injury.

Abstract: This case demonstrates very clearly the concept of the contracoup injury. While physical examination showed that the injury was sustained to the right posterior parietal-occipital region, it was the contracoup injury in the left frontal area which proved to be most devastating to the patient. It also underscores the necessity of emergent CT scanning of the calvarium and brain in closed head injuries in patients with positive neurologic findings

Evidence for Regulation of Peptide-YY Release by the Proximal Gut

Abstract: Peptide-YY (PYY) is a novel enteric peptide that is structurally related to pancreatic polypeptide and neuropeptide-Y. The objectives of the present experiments were to characterize the following aspects of PYY metabolism: the distribution of PYY in the canine gastrointestinal tract, the release of PYY in response to oral ingestion of a mixed meal or intraduodenal (ID) administration of oleic acid, the effect of ileocolectomy on the release of PYY in response to ID administration of oleic acid when transit of chyme to the distal ileum and colon is prevented, the effect of interruption of intramural neural pathways of the small bowel on the release of PYY, and the effect of iv cholecystokinin on the release of PYY. The results of these experiments demonstrate that PYY immunoreactivity is distributed primarily in the terminal ileum, colon, and rectum. Circulating levels of PYY increase significantly (P less than 0.05) within 10-30 min after ingestion of a meal or to ID administration of a fatty acid. Complete interruption of the flow of chyme to the site of PYY-containing cells (i.e. ileum-colon) did not block the release of PYY; however, ileocolectomy abolished the release of PYY in response to ID administration of oleic acid. Severance of intramural neural pathways along the small bowel did not alter the release of PYY in response to an oral meal. Intravenous administration of graded doses of cholecystokinin stimulated the release of PYY in a dose-related manner. The results of these experiments indicate that the release of PYY from the distal ileum and colon is controlled, at least in part, by an extramural neural, endocrine, or a combination of both types of mechanisms which originate in the foregut.

Endocytosis of hyaluronic acid by rat liver endothelial cells. Evidence for receptor recycling

Abstract: Hyaluronic acid (HA) is cleared from the blood by liver endothelial cells through receptor-mediated endocytosis [Eriksson, Fraser, Laurent, Pertoft & Smedsrod (1983) Exp. Cell Res. 144, 223-238]. We have measured the capacity of cultured rat liver endothelial cells to endocytose and degrade 125I-HA (Mr approximately 44,000) at 37 degrees C. Endocytosis was linear for 3 h and then reached a plateau. The rate of endocytosis was concentration-dependent and reached a maximum of 250 molecules/s per cell. Endocytosis of 125I-HA was inhibited more than 92% by a 150-fold excess of non-radiolabelled HA. HA, chondroitin sulphate and heparin effectively competed for endocytosis of 125I-HA, whereas glucuronic acid, N-acetylglucosamine, DNA, RNA, polygalacturonic acid and dextran did not compete. In the absence of cycloheximide, endothelial cells processed 13 times more 125I-HA in 6 h than their total (cell-surface and intracellular) specific HA-binding capacity. This result was not due to degradation and rapid replacement of receptors, because, even in the presence of cycloheximide, these cells processed 6 times more HA than their total receptor content in 6 h. Also, in the presence of cycloheximide, no decrease in 125I-HA-binding capacity was seen in cells processing or not processing HA for 6 h, indicating that receptors are not degraded after the endocytosis of HA. During endocytosis of HA at 37 degrees C, at least 65% of the intracellular HA receptors became occupied with HA within 30 min. This indicates that the intracellular HA receptors (75% of the total) function during continuous endocytosis. Hyperosmolarity inhibits endocytosis and receptor recycling in the asialoglycoprotein and low-density-lipoprotein receptor systems by disrupting the coated-pit pathway [Heuser & Anderson (1987) J. Cell Biol. 105, 230a; Oka & Weigel (1988) J. Cell. Biochem. 36, 169-183]. Hyperosmolarity inhibited 125I-HA endocytosis in liver endothelial cells by more than 90%, suggesting use of a coated-pit pathway by this HA receptor. We conclude that liver endothelial cell HA receptors are recycled during the continuous endocytosis and processing of HA.

Infections due to Xylohypha bantiana (Cladosporium trichoides).

Abstract: Thirty culture-documented cases of infection caused by Xylohypha bantiana (synonyms, Cladosporium bantianum, Cladosporium trichoides) were identified in the world literature; 26 cases involved the central nervous system (CNS) and most frequently presented as chronic headache followed by fever and hemiparesis. Phaeohyphomycosis due to X. bantiana occurs worldwide, predominantly in young males. Pharmacologic immunosuppression was not an important predisposing factor. However, four patients had a history of systemic nocardiosis or facial phaeohyphomycosis caused by Alternaria species. Chest radiography revealed no pulmonary infiltrates. Computed tomography of the brain demonstrated a mass defect, the frontal lobes being the most common sites of infection. Lumbar puncture usually demonstrated an elevated opening pressure, elevated cerebrospinal fluid protein level, hypoglycorrhachia, and cultures were negative. No preoperative clinical or laboratory features indicated CNS fungal infection. Complete neurosurgical resection of the lesion was the most important therapeutic intervention determining survival; systemic antifungal chemotherapy apparently did not influence outcome. The survival rate of 35% for all patients and of 45% for all neurosurgically treated patients was higher than had previously been reported, probably because patients dying from infections confirmed only histopathologically were excluded.

Intestinal parasites of sympatric Pan troglodytes and Papio spp. at two sites: Gombe (Tanzania) and Mt. Assirik (Senegal)

Abstract: Experimental and clinical parasitology need natural baselines or “controls”. We present normative data intestinal parasite loads in two genera of African primates. Wild Pan troglodytes and Papio spp. were studied at two sites: Gombe in Tanzania (P. anubis) and Mt. Assirik in Senegal (P. papio). Presence or absence of parasites, especially nematodes, was recorded from fecal specimens. Gombe's primates were more often infected than were Mt. Assirik's. At Gombe, but not at Mt. Assirik, chimpanzees seemed to have a higher incidence of infection than baboons. Comparison of three baboon troops yielded apparent differences in prevalence of infection. No differences in infection were found between the wet and dry seasons in Mt. Assirik's chimpanzees.

Segmental mediolytic arteritis. A clinicopathologic and ultrastructural study of two cases.

Abstract: We describe the histopathologic and ultrastructural changes in two cases of segmental mediolytic arteritis (SMA) and summarize the clinical and pathologic findings in previous reports. SMA is initiated by the transformation of the arterial smooth-muscle cytoplasmic contents into a maze of dilated vacuoles containing edema-like fluid. With vacuolar rupture, the smooth-muscle cells are disrupted and the mediolytic process completed. Mediolysis is accompanied by fibrin deposition and hemorrhages at the adventitio-medial junction and within the media. Inflammation is inconstant and limited to the periadventitial tissues. Transmural mediolysis leads to the formation of arterial wall gaps--defects in the vascular wall bridged by a serofibrinous layer. The serosal and intramural arteries and arterioles of the jejunum and the epicardial coronary arteries were the targets of SMA in this report. SMA occurs in two clinical settings: (a) in abdominal muscular arteries and arterioles of predominantly elderly patients presenting either with ischemic bowel disease or shock, and (b) in the coronary arteries of neonates in conditions associated with severe hypoxemia. We conclude that SMA is the result of an inappropriate vasospastic response expressed in a splanchnic vascular bed undergoing vasoconstriction as a response to shock or severe hypoxemia.

Role of prostaglandins and cAMP in the secretory effects of cholera toxin.

Abstract: The role of adenosine 3',5'-monophosphate (cAMP) and prostaglandins in the pathogenesis of experimental cholera was evaluated. Fluid accumulated in the rabbit intestinal loop model after 16 hours of incubation with cholera toxin, prostaglandin E1, or prostaglandin E2, but not with membrane-permeable derivatives of cAMP or forskolin. Dibutyryl cAMP triggered a small, transient intestinal fluid accumulation response by 4.5 hours; however, the fluid was completely absorbed by 9 hours. After exposure of intestinal loops to cholera toxin, prostaglandin E was released into the intestinal lumen in a concentration-dependent manner independent of cAMP. Thus, not only cAMP, but also prostaglandins may regulate water and electrolyte secretion in cholera.

Specific-locus mutations induced in eukaryotes (especially mammalian cells) by radiation and chemicals: a perspective

Abstract: In the course of discovering the first mutagen (X-rays) just over 60 years ago, Herman J. Muller asked whether X-rays induced single-gene mutations and/or chromosomal (multiple-gene) mutations. To a large extent, his question has set the agenda for mutagenesis research ever since. We explore historically the answers to this question, with special emphasis on recent developments in the field of mammalian cell mutagenesis. Studies indicate that ionizing radiation and many chemical mutagens/carcinogens induce both gene and chromosomal mutations; however, only certain genetic systems permit the recovery and analysis of both classes of mutations. Few chemical mutagens induce only gene mutations in mammalian cells; instead, most mutagens appear to induce both classes of mutations, with chromosomal mutations (especially multilocus deletions) predominating at high doses. These results have implications regarding the mechanisms of mutagenesis, the role of chromosomal mutations in carcinogenesis and hereditary disease, and the type of data required for risk assessment of physical and chemical mutagens/carcinogens.

Parathyroid hormone as a smooth muscle relaxant.

Abstract: I. Introduction THE ROLE of PTH as a major physiological regulator of calcium homeostasis has been studied extensively, and both bone and kidney have long been recognized as classical major target organs for PTH action (1, 2). More recently, however, evidence has accumulated which indicates that PTH has diverse biological effects in other tissues as well. For example, in the gastrointestinal tract, PTH has been reported to act directly to stimulate calcium transport in the chick duodenum (3) and to increase gastrin release from the pig stomach (4, 5). As discussed in detail later, PTH also is an inhibitor of smooth muscle contraction in the cardiovascular system, in the gastrointestinal (GI) tract, and in other tissues such as trachea, uterus, and vas deferens. In the central nervous system, immunoreactive PTHlike activity has been detected in human cerebrospinal fluid, and its release has been reported from the pituitary and from different regions of the brain of a variety of vertebrates, including mamma...

Human genotoxicity: pesticide applicators and phosphine

Abstract: Fumigant applicators who, 6 weeks to 3 months earlier, were exposed to phosphine, a common grain fumigant, or to phosphine and other pesticides had significantly increased stable chromosome rearrangements, primarily translocations in G-banded lymphocytes. Less stable aberrations including chromatid deletions and gaps were significantly increased only during the application season, but not at this later time point. During fumigant application, measured exposure to phosphine exceeds accepted national standards. Because phosphine is also used as a dopant in the microchip industry and is generated in waste treatment, the possibility of more widespread exposure and long-term health sequelae must be considered.

Cytoplasmic pH in pulmonary macrophages: recovery from acid load is Na+ independent and NEM sensitive.

Abstract: The pulmonary macrophage plays a primary role in the immunological defense of the lung. Although many studies have been devoted to elucidation of its phagocytic and secretory functions, little is known of its membrane transport properties or of how it regulates intracellular pH (pHi). The purpose of this study, therefore, was to determine base-line pHi and the mechanism(s) by which the cell recovers pHi when challenged with an intracellular acid load. Through the use of the pH-sensitive fluorescent dye, 2,7-biscarboxyethyl-5(6)-carboxy-fluorescein (BCECF), base-line pHi was estimated to be 7.24 +/- 0.03. Cells were acidified by two methods, nigericin and weak acids, while recovery (dpHi/dt) was monitored. The rate of recovery was found to be independent of external Na+ and K+ and was insensitive to amiloride. Pretreatment with 4,4'-diiso-thiocyanatostilbene-2,2'-disulfonic acid, an inhibitor of Cl- -HCO3- exchange, was also without effect on recovery from an intracellular acid load in these cells, under nominally HCO3- -free conditions. In contrast, N-ethylmaleimide (NEM) and N,N'-dicyclohexylcarbodiimide, nonspecific inhibitors of proton adenosinetriphosphatases (ATPases), virtually abolished pHi recovery. Efflux of H+ equivalents by pulmonary macrophages was measured by techniques involving both pH stat titration and the effect on fluorescence of extracellular BCECF. Basal H+ extrusion was approximately 2.75 +/- 0.64 nmol H+.min-1.10(6) cells-1 and was enhanced to approximately 26.0 +/- 6.95 nmol H+.min-1.10(6) cells-1 in acid-loaded cell suspensions. The basal rate of H+ extrusion was reduced to approximately 0.84 +/- 0.31 nmol H+.min-1.10(6) cells-1 in the presence of 1 mM NEM. These results suggest that recovery of cytoplasmic pH from an intracellular acid load, as well as regulation of pHi, under the conditions examined, is not mediated by a Na+-H+ exchanger in these cells. Rather, the data are consistent with the presence of an H+-ATPase in the plasma membrane of pulmonary macrophages.

Distinguishing normal and demented elderly with the selective reminding test

Abstract: The selective reminding (SR) procedure, a popular technique for the study of verbal memory, was used to investigate aspects of memory functioning in a large group of normal elderly and in a smaller group of elderly subjects with Alzheimer Type Dementia (ATD). One hundred thirty-four normal elderly (mean age = 79.53 years) subjects and 21 ATD subjects (mean age = 68.3 years) were administered four versions of the SR test as part of a longitudinal study of risk factors in the development of dementia. Normative data were obtained for multiple components of memory functioning within the elderly sample. Test-retest reliability was .84 for long-term retrieval (LTR), .89 for sum of recall, and .92 for consistent retrieval. Clinical validity studies revealed that the components of sum of recall, storage estimate, LTR, and consistent long-term storage (CLTS) were most valuable in distinguishing mild ATD from normal aging. Positive predictive values ranged from 86% for CLTS, 89% for LTR, 91% for sum of recall, and 100% for storage estimate. These findings suggest that the SR test has considerable clinical utility in differentiating normal aging from dementia, and has promise as a useful tool in the preclinical detection of ATA.

Pharmacologic differentiation between inositol-1,4,5-trisphosphate-induced Ca2+ release and Ca2+- or caffeine-induced Ca2+ release from intracellular membrane systems.

Abstract: Various known Ca2+ channel blockers and intracellular Ca2+ antagonists have been tested for effects of inositol-1,4,5-trisphosphate (IP3)-induced Ca2+ release from isolated canine brain microsomes. In agreement with previous reports, heparin, p-chloromercuribenzoic acid, W-7, cinnarizine, flunarizine, certain local anesthetics, La3+, and Ca2+ inhibit the release of Ca2+ induced by addition of IP3. In addition, we report here pronounced inhibition of IP3-induced Ca2+ release by low levels of Cd2+, by relatively high concentrations of TMB-8, and by phytic acid. In contrast, a number of blockers of other Ca2+ channels (nifedipine, verapamil, dantrolene, dithiothreitol, and ruthenium red) have relatively little or no effect on IP3-induced Ca2+ release from brain microsomes. The relative ineffectiveness of substances that inhibit Ca2+- or caffeine-induced Ca2+ release from skeletal muscle sarcoplasmic reticulum suggests that release of Ca2+ from caffeine- and IP3-sensitive neuronal Ca2+ stores is likely to be mediated by different channels. Further evidence that different channels are involved is presented by way of demonstration of the lack of Ca2+-induced Ca2+ release from these brain microsomes and the lack of effect on sarcoplasmic reticulum caffeine-induced Ca2+ release of certain inhibitors of IP3-induced Ca2+ release used here. Among IP3-induced Ca2+ release blockers, La3+ appeared to be exceptional in its ability to stimulate microsomal Ca2+ uptake sufficiently to attenuate release of Ca2+ induced by IP3. Most blockers of IP3-induced Ca2+ release appear not to function by way of inhibiting K+ counter-ion movements (valinomycin does not reverse the inhibition) but rather by way of direct interaction with the IP3 receptor or the Ca2+ channel that mediates the IP3-induced Ca2+ release. Inhibition of [3H]IP3 binding to the microsomes by phytic acid, heparin, pyrophosphate, p-chloromercuribenzoic acid, and Ca2+ could be demonstrated but not by the other substances tested.

Histopathology and immunohistologic demonstration of the distribution of Rickettsia typhi in fatal murine typhus

Abstract: An 81-year-old woman had chills, fever, nausea, vomiting, and epigastric pain. On day 3 she had hematuria and was treated with trimethoprim-sulfamethoxazole. On day 5 she had a cough, hypotension, anemia, azotemia, and elevated hepatic enzyme levels. Her condition deteriorated with thrombocytopenia, anuria requiring dialysis, edema, and hypoalbuminemia. Treatment with chloramphenicol and doxycycline was started on day 10. By day 11, she was in hypotensive shock; on day 12 she had seizures and died. Murine typhus was diagnosed by demonstration of antibodies to Rickettsia typhi by indirect immunofluorescence. Necropsy revealed interstitial pneumonia, pulmonary edema, hyaline membranes, alveolar hemorrhages, petechiae and vasculitis in the central nervous system, interstitial myocarditis, multifocal interstitial nephritis and hemorrhages, splenomegaly, portal triaditis, and mucosal hemorrhages in urinary tract. Immunofluorescent R. typhi were demonstrated in the lungs, brain, kidneys, liver, and heart. This unusual death occurred in an elderly patient without rash who was treated too late with antirickettsial drugs.

Interspecific competition among Aedes aegypti, Ae. albopictus, and Ae. triseriatus (Diptera: Culicidae): larval development in mixed cultures.

Abstract: Interactions among the larvae of Aedes aegypti (L.), Ae. albopictus (Skuse), and Ae. triseriatus (Say) were studied in trispecific and bispecific mixed populations under laboratory and field conditions. Competitive stress (as evidenced by the average time to first, 50, and 75% pupation and the total pupation periods for mixed populations of each species in comparison with their single species controls) was more pronounced in mixed cultures reared in glass jars in the laboratory than in tires under field conditions. In the laboratory, the larval development of Ae. aegypti reared together with Ae. albopictus or Ae. triseriatus, or both, larvae was accelerated significantly. Conversely, the time to pupation for Ae. albopictus and Ae. triseriatus was delayed when reared with Ae. aegypti. However, the average wing length of female Ae. albopictus and Ae. triseriatus was greater in the mixed cultures than in single species cultures. These data indicated that the effect of intraspecific competition was greater than interspecific competition. Adequate food and higher temperature appeared to promote rapid development and higher survival of the immature stages of the three Aedes species in tires placed in the field. In general, Ae. triseriatus larvae required a longer period for larval development and had greater larval mortality than either Ae. aegypti or Ae. albopictus. In mixed populations of Ae, albopictus and Ae. aegypti in the jars and food-rich tires, the periods needed to attain first, 50, and 75% cumulative pupation were not significantly different than in single species controls. We conclude that no clear-cut displacement occurred in mixed experimental populations of Ae. aegypti and Ae. albopictus.