Showing papers by "University of Maryland, Baltimore published in 1975"
TL;DR: It is concluded that the granulosa cells are responsible for the maintenance of the oocytes in the dictyate stage within the follicle, and appear to exert their inhibitory influence upon meiosis by secretion of a chemical message into follicular fluid.
Abstract: Isolated oocytes will resume meiosis spontaneously in vitro whereas follicle-enclosed oocytes will remain in the dictyate stage when cultured unless they have been exposed to gonadotropins in vivo or in vitro. To examine the source of the follicular inhibitory influence, porcine oocytes have been cultured alone, with hemisections of follicle wall, granulosa cells, or with follicular fluid. Oocytes isolated from medium-sized (3–5 mm) follicles resumed meiosis when cultured; 77.5 ± 3.4% matured beyond the dictyate stage. When oocytes were cultured in the presence of follicle wall hemisections of medium and large (6–12 mm) follicles, the percentage of maturing oocytes was significantly reduced. The maturation of oocytes cultured in a medium containing 50% follicular fluid from small or large follicles was significantly inhibited. Resumption of meiosis was completely inhibited by co-culture of isolated oocytes with 107 granulosa cells from small, medium or large follicles. Addition of serially diminishing amo...
310 citations
TL;DR: The recovery of Salmonella typhi from blood, rectal swab, urine, bone-marrow, and rose spots was compared in 62 patients with typhoid fever, most of whom had received some antibiotic therapy before presentation.
269 citations
TL;DR: In this article, the instability of pyrroline-5-car-ylate reductase from Escherichia coli has been studied, leading to the conclusion that the rate of decomposition is sensitive to concentration of the compound.
140 citations
TL;DR: Capillaries in the cat hypothalamus receive axon terminals which are comparable to neurovascular junctions in cerebral and systemic arteries and arterioles, in contrast to cerebral arterial vessels, which are supplied by the peripheral autonomic nervous system.
Abstract: Capillaries in the cat hypothalamus receive axon terminals which are comparable to neurovascular junctions in cerebral and systemic arteries and arterioles. The innervation of capillaries in the central nervous system may be derived from central neurons, in contrast to cerebral arterial vessels, which are supplied by the peripheral autonomic nervous system.
139 citations
TL;DR: Circulating antibodies to live tissue-cultured human-insulinoma cells were identified in 34 out of 39 insulin-dependent diabetic patients by an indirect immunofluorescent technique, suggesting that autoimmune mechanisms are important in the pathogenesis of most cases of insulin-requiring diabetes.
134 citations
TL;DR: The results show that the brain of the 1- to 10-day-old suckling rat pup is particularly sensitive to lead exposure with residual effects produced on learning present in the 8- to10-wk-old adult after blood lead concentrations have returned to control values.
101 citations
TL;DR: The main content of the completed research is summarized and methodological criticisms are made and future considerations for research on families of drug abusers are suggested.
Abstract: This paper reveiws all relevant literature concerning the family background of compulsive drug abusers. The main content of the completed research is summarized and methodological criticisms are made. Future considerations for research on families of drug abusers are suggested.
85 citations
TL;DR: Upon entry into the cytoplasm of irradiated chicken embryo cells in slide chamber cultures infected over a 2-h period, yolk sac-grown virulent (Breinl strain) and attenuated (E strain) Rickettsia prowazeki underwent indistinguishable reproducible intracellular growth cycles.
Abstract: Upon entry into the cytoplasm of irradiated chicken embryo cells in slide chamber cultures infected over a 2-h period, yolk sac-grown virulent (Breinl strain) and attenuated (E strain) Rickettsia prowazeki underwent indistinguishable reproducible intracellular growth cycles. They promptly entered an exponential growth phase, without detectable lag and without microscopic evidence for any unusual early replicative phase. The generation time for both strains was 8.8 to 8.9 h at 34 C. During most of this period, the state of the organisms and growth were very similar from one cell to another. The exponential-growth phase continued for at least 36 to 48 h, when the rickettsiae became too numerous to count by microscopic examination. Between about 36 and 48 h, cells packed with rickettsiae began irregularly to break down and release organisms. These began to initiate new infection cycles in previously uninfected cells over many hours, as demonstrated by the rise in percentage of cells infected, yielding a highly disordered infected culture with different cells containing rickettsiae in diverse stages of growth. The organisms underwent regular minor changes in morphology, similar to those seen in bacterial cultures, in the first infection cycle. As the cells became packed with rickettsiae, the microorganisms regularly diminished in size to become minute coccobacillary to coccoid forms. However, the rickettsiae in the second and subsequent infection cycles in aging cultures often assumed filamentous or swollen bizarre forms. Only the first infection cycle conformed closely to the concept of a one-step growth cycle. A set of terms is proposed and defined for the infection cycle.
84 citations
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TL;DR: Penetration of a liquid adhesive into human artificial and natural white spots, both acid-conditioned and nonconditioned, was studied and all artificial white spots showed penetration of the adhesive.
Abstract: Penetration of a liquid adhesive into human artificial and natural white spots, both acid-conditioned and nonconditioned, was studied. All artificial white spots showed penetration of the adhesive. Acid-conditioned natural lesions exhibited penetration to a lesser amount than in vitro lesions. Penetration in nonconditioned natural lesions was not apparent.
TL;DR: Evidence supporting this hypothesis is provided by demonstrating that both the evoked and emitted P300 potentials are similarly affected by variation in event probability.
Abstract: There have been a number of reports of a cerebral potential occurring at about the time of an expected but absent stimulus when absence provided significant information for the subject. This potential consists primarily of a positive peak occurring with a latency of about 300 msec with respect to the time of stimulus absence and is referred to as an emitted P300 potential. It has been conjectured that the emitted P300 is a manifestation of the same process that underlies the evoked P300. Evidence supporting this hypothesis is provided by demonstrating that both the evoked and emitted P300 potentials are similarly affected by variation in event probability. A paradigm was used in which click presence and absence provided information. The relative probability of click presence and absence was experimentally manipulated. Both evoked and emitted p300 amplitude responded in the same way to event probability, larger for the less frequent event and smaller for the more frequent event.
TL;DR: It is shown that, contrary to general belief, chiggers can acquire R .
Abstract: A fundamental concept in the ecology of ectoparasite-borne disease is that of the reservoir, or the wellspring of the infection in nature during interepidemic periods. In the case of chigger-borne rickettsiosis (scrub typhus), it has often been argued that chiggers (larval trombiculid mites) are not only the vectors but also the true reservoirs of the infection and that the small mammals (theraphions) that serve as hosts of the chiggers are of no importance as a source of rickettsiae for the chiggers.’ This point of view has been based largely upon several factors, namely, the known transovarian transmission of the causative agent, Rickettsia tsutsugamushi. from mother to progeny in certain species of chiggers,’ the demonstration of the efficiency of the mechanism of transovarian transmission by Rapmund and his colleagues,+-” the difficulty or impossibility to show that chiggers can acquire R . tsutsugamushi while feeding on infected hosts in the laboratory,’. c l l the fact that chiggers are unique among vectors in that in their lifetime, they are parasitic only in one stage (i.e., as larvae) and normally attach to, and feed upon, only one vertebrate and therefore could not acquire an infection from one such host and transmit it later directly to a second, and, finally, the widespread belief that chiggers do not imbibe blood but, instead, feed solely on serum exudate when in the parasitic stage and thus are unlikely to come in contact with pathogens that circulate in the blood of the host.‘, In the present paper, it is shown that, contrary to general belief, chiggers can acquire R . tsutsugarnushi while feeding on rickettsemic mice and that, when tested by pools of chiggers, this acquisition is relatively frequent. Persistence of acquired rickettsiae for at least 1-2 weeks in the chiggers is demonstrated, and a single case of presumed transovarian transmission to the next generation is reported. The preliminary data presented suggest, somewhat surprisingly, that in nature, under certain conditions, a small but perhaps significant proportion of chiggers may partially feed on one host and then later feed to repletion on a second one, raising the possibility that such “reattached” chiggers may
TL;DR: Viral capsid protein V-2 was depleted in the intermediate and smooth endoplasmic reticulum, suggesting that these membranes may serve as the sites for viral maturation.
Abstract: Enzymatic markers and electron microscopy were utilized to determine the cellular origin of the membrane types isolated from type 2 dengue virus-infected BHK cells by discontinuous sucrose gradient centrifugation. The results showed an apparent separation of plasma membrane, smooth and rough endoplasmic reticulum with increasing density. Virus-induced protein and RNA synthesis, as indicated by the incorporation of radiolabled precursors, was localized on the rough endoplasmic reticulum. Glycosylation, measured by the incorporation of radiolabeled glucosamine into membrane-associated proteins, was most active in the bands of intermediate and smooth endoplasmic reticulum. Polyacrylamide gel electrophoresis of isolated membrane bands, radiolabeled in the presence of actinomycin D, after pulse inhibition by cycloheximide, revealed seven virus-specific proteins associated with all membrane fractions. Viral structural protein V-3, and nonstructural proteins NV-3 and NV-2, increased with decreasing density, whereas NV-5 and NV-4 remained constant. The viral capsid protein V-2 was depleted in the intermediate and smooth endoplasmic reticulum, suggesting that these membranes may serve as the sites for viral maturation. NV-3 was the most prominent virus-specified protein found in the plasma membrane.
TL;DR: Since there is evidence that retention esophagitis is a premalignant condition, it should be possible to prevent the development of carcinoma in achalasia by early cardiomyotomy in cases in which hydrostatic dilatation is not completely effective.
TL;DR: It is suggested that HTX acts on the ionic conductance modulator of the acetylcholine receptor in a manner similar to its semisynthetic derivative perhydrohistrionicotoxin, which has a variety of effects on the function of mammalian and amphibian nerve-muscle preparations.
TL;DR: A study of the supply to the feline brain by the carotid-middle cerebral arteries was conducted using in vivo transcardiac injection with a mixture of micropaque and carbon black to visualize modifications in the filling pattern of the arterial vessels.
Abstract: A study of the supply to the feline brain by the carotid-middle cerebral arteries was conducted using in vivo transcardiac injection with a mixture of micropaque and carbon black. Modifications in the filling pattern of the arterial vessels were visualized following short-term occlusion of a middle cerebral artery. A modified surgical method to induce occlusion of the M-1 segment of the middle cerebral artery is also described.
TL;DR: An unusual lipid storage disese is chracterized by the accumulation of hematoside (Gms3) in the patient's liver and brain, which is the first disorder caused by deficiency in ganglioside biosynthesis to be described in man.
Abstract: An unusual lipid storage disese is chracterized by the accumulation of hematoside (Gms3) in the patient's liver and brain. In contrast to the other sphingoliidoses, the accumulation of Gm3 is not the result of a defective catabolic reaction, but is the first disorder caused by deficiency in ganglioside biosynthesis to be described in man.
TL;DR: In this article, a class of bilinear estimation problems involving single-degree-of-freedom rotation is formulated and resolved, and an effective synthesis procedure for continuous-time estimation is provided, and a generalization to estimation on arbitrary Abelian Lie groups is included.
Abstract: A class of bilinear estimation problems involving single-degree-of-freedom rotation is formulated and resolved. Continuous-time problems are considered here, and discrete-time analogs will be studied in a second paper. Error criteria, probability densities, and optimal estimates on the circle are studied. An effective synthesis procedure for continuous-time estimation is provided, and a generalization to estimation on arbitrary Abelian Lie groups is included. Applications of these results to a number of practical problems including frequency demodulation will be considered in a third paper.
TL;DR: Spheroidal, granular, and fibrillar particles observed in human aortic valve calcifications suggest that the latter are also amorphous calcium phosphate and may be precursors of hydroxyapatite.
Abstract: Spheroidal, granular, and fibrillar particles were observed in human aortic valve calcifications. Spheroids were similar to amorphous calcium phosphate shown previously in synthetic preparations and in bone. The frequent coexistence of needle shaped hydroxyapatite crystals with granular and fibrillar particles suggests that the latter are also amorphous calcium phosphate and may be precursors of hydroxyapatite. All three types of particles had a tendency to form laminated and spherular secondary structures and failed to give a crystalline pattern by electron diffraction.
TL;DR: Neutralizing activity against d Dengue virus types 1–4 was observed in milk samples from 5 non-immune and 29 dengue immune women and did not decrease over a period of ten months after delivery.
Abstract: Neutralizing activity against dengue virus types 1--4 was observed in milk samples from 5 non-immune and 29 dengue immune women. Anti-dengue activity in milk and colostrum was found only in the lipid component. The inhibitory activity is directed against the virus and not cell surfaces. When immunoglobulin types IgM,IgA, IgG were isolated from colostrum from dengue immune women, no antibody activity was found. Anti-dengue activity in human milk did not decrease over a period of ten months after delivery.
TL;DR: In this article, the efficacy of trimethoprim-sulfamethoxazole was compared with that of oral amoxicillin in therapy of typhoid fever due to both epidemic chloramphenicol-resistant and endemic chloramphensicol-sensitive Salmonella typhi.
Abstract: The efficacy of orally administered trimethoprim-sulfamethoxazole was compared with that of oral amoxicillin in therapy of typhoid fever due to both epidemic chloramphenicol-resistant and endemic chloramphenicol-sensitive Salmonella typhi. Both drug regimens were effective and of comparable value in treatment of chloramphenicol-resistant infections, as measured by duration of fever (124 hr and 115 hr, respectively) and duration of bacteremia (1.0 and 0.4 days, respectively). Trimethoprim-sulfamethoxazole therapy of infections due to chloramphenicol-sensitive S. typhi resulted in more rapid lysis of fever than did amoxicillin therapy. Trimethoprim and sulfamethoxazole were not synergistic in vitro against the chloramphenicol-resistant strain of S. typhi, and the role of sulfamethoxazole in treatment of such infections appears to be minimal. Oral administration of trimethoprim-sulfamethoxazole is effective therapy of chloramphenicol-resistant, and probably of ampicillin-amoxicillin-resistant, typhoid fever.
TL;DR: A model is proposed in which the conformation of the Mg-2+-ATPase is important in the utilization of energy derived from the electron transport chain and this function is independent of the catalytic activity of the N,N'-dicyclohexylcarbodiimide or the crude soluble ATPase of the wild type.
TL;DR: In this paper, the authors compare the South China Sea dispute with the Tiaoyut'ai-Senkaku dispute of the East China Sea between China and Japan and conclude that the settlement of one is likely to bear on that of the other as well as on the development of marine resources in the two China Seas.
Abstract: The four groups of uninhabited coral islets scattered in the South China Sea have been the object of territorial claims by the surrounding coastal states for the past few decades. The ownership issue became a serious territorial dispute in January 1974, when the forces of the People's Republic of China and the Republic of Vietnam clashed over the Paracel Islands. In many points, this South China Sea dispute is so similar to the Tiaoyut'ai‐Senkaku dispute of the East China Sea between China and Japan that the settlement of one is likely to bear on that of the other as well as on the development of marine resources in the two China Seas. It is not possible to determine the validity of the conflicting claims in either case. Relying on the available historic facts, however, China's claim to the Paracel and Spratly islands appears to be relatively stronger than that of Vietnam.
TL;DR: Vinblastine and demecolcine were shown to be potent inducers of autophagy also in Ehrlich ascites tumor cells in vitro and it is suggested that this effect is rather dependent on direct effect on membranes of endoplasmic reticulum than on the breakdown of microtubules by these compounds.
TL;DR: Lactulose shows promise for the treatment of shigella carriers but appears ineffective in treatment of acute shigellosis.
Abstract: Antibiotic-resistant shigella are increasingly prevalent. Lactulose, a non-absorbable disaccharide, was investigated as an alternative therapy for shigella infection on the hypothesis that the short-chain fatty acids (inhibitory to shigella) resulting from metabolism of lactulose by normal colonic flora would diminish shigella excretion. A long-term antibiotic-refractory carrier (large bowel) excreting 10(4) to 10(7)Shigella sonnei/g of feces was given two courses of lactulose (of 24 and 16 days duration). During lactulose therapy, excretion of shigella was greatly diminished (24-day course) or suppressed below detectable levels (16-day course), but returned to pretreatment levels upon discontinuation of lactulose. The volunteers who developed induced shigellosis during an efficacy test of oral Shigella flexneri 2a vaccine were randomly given oral ampicillin, lactulose, or placebo in double-blind fashion. Daily rectal cultures were taken. After 4 days of therapy, cultures were still positive in four out of four men on lactulose, three of three on placebo and none of three on ampicillin. Mean stool pH of men receiving lactulose (6.1) was significantly lower than those getting ampicillin (7.4), P < 0.01, or placebo (7.0), P < 0.05. Only in the lactulose group was mean stool pH during therapy significantly decreased compared with the level off therapy (6.1 versus 7.1), P < 0.02. Lactulose shows promise for the treatment of shigella carriers but appears ineffective in treatment of acute shigellosis.
TL;DR: It was observed that LH-RH, when mixed with artificial CSF, and allowed to stand at room temperature (24 C), also lost all biological potency even though immunoreactivity was retained.
Abstract: Cerebral spinal fluid (CSF) was examined for the presence of luteinizing hormone-releasing hormone (LH-RH) at times when copious amounts of LH were being secreted by the adenohypophysis. A "push-pull" apparatus was designed which permitted the perfusion of artificial CSF through the 3rd ventricle from the region of the medial preoptic area (MPOA) to the site of recollection adjacent to the median eminence (ME). It was observed on radioimmunoassay that LH-RH concentrations were low in CSF and peripheral plasma of Nembutal-blocked proestrous rats. Intraarterial injections of LH-RH did not increase CSF concentrations of this decapeptide, although a significant release of pituitary LH occurred. Further, electrochemical stimulation of the MPOA also elevated plasma LH without altering CSF-LH-RH levels. When synthetic LH-RH, dissolved in artificial CSF, was perfused through the 3rd ventricle, plasma LH levels rose dramatically, and a significant decrease in the concentration of LH-RH in the CSF efflux was observed on collection and assay. CSF collected from MPOA-stimulated rats also was tested for biologically active LH-RH by its reinjection into Nembutal-blocked proestrous recipients. While such injections failed to induce pituitary LH release, it was observed that LH-RH, when mixed with artificial CSF, and allowed to stand at room temperature (24 C), also lost all biological potency even though immunoreactivity was retained. The results suggest that CSF does not serve as a vehicle for transport of LH-RH to the median eminence under physiological conditions.
TL;DR: In this article, critical values for the one-sample and two-sample Kolmogorov-Smirnov statistics with a particular weight function are compared and found to be greatly different.
Abstract: Critical values for the one-sample and the two-sample Kolmogorov-Smirnov statistics with a particular weight function are compared and found to be greatly different. The difference is shown to be due to the marked sensitivity of the one-sample statistic to the values of the first and last order statistics of the sample distribution.