Showing papers by "University of Texas Health Science Center at San Antonio published in 1984"

Mapping the body representation in the SI cortex of anesthetized and awake rats

Abstract: We have used single unit recording techniques to map the representation of cutaneous and joint somatosensory modalities in the primary somatosensory (SI) cortex of both anesthetized and awake rats. The cytoarchitectonic zones within the rat SI were divided into the following main categories: (1) granular zones (GZs)--areas exhibiting koniocortical cytoarchitecture (i.e., containing dense aggregates of layer IV granule cells), (2) perigranular zones (PGZs)--narrow strips of less granular cortex surrounding the GZs, and (3) dysgranular zones (DZs)--large areas of dysgranular cortex enclosed within the SI. The narrow strip between the SI and the rostrally adjacent frontal agranular cortex was termed the "transitional zone" (TZ). Initial computer-based studies of the properties of cutaneous receptive fields (RFs) in SI showed that, although there were differences in response threshold, adaptability, frequency response, and overall RF size and shape of adjacent neurons, the size and location of the "centers" of the RFs were quite constant and were similar to those seen in multiple unit recordings. The same was true of RFs of single neurons recorded through different anesthetic states. The body representation in SI was first mapped by determining single unit and unit cluster RFs within a total of 2,170 microelectrode penetrations in barbiturate-anesthetized rats. Cutaneous RFs in the GZs were quite discrete. Thus, a single, finely detailed, continuous map of the cutaneous periphery was definable within the GZs themselves. Only the forepaw had a double representation. RFs in the PGZs were larger and more diffuse, but since they covered roughly the same skin areas as the RFs in the most closely adjacent GZs, they fit into the same body map. Neurons in the DZs were unresponsive to any sensory stimuli in the anesthetized animal. In chronically implanted, freely moving, awake animals cutaneous RFs were larger and more volatile than in the anesthetized, but the accuracy of the map was clearly preserved by the fact that the locations of the RF centers (which often must be defined quantitatively) were unchanged. The PGZs and DZs in the awake animals exhibited a multimodal convergence of cutaneous and joint movement RFs within single vertical penetrations, or even on single neurons. Directionally specific and bilateral cutaneous RFs were also observed in the DZs. It was concluded the DZs are more associational or integrative areas within the SI, but they could not be shown to comprise a distinct and separate body representation.(ABSTRACT TRUNCATED AT 400 WORDS)

Risk factors for sudden death after acute myocardial infarction: Two-year follow-up☆

Abstract: The risk of sudden coronary death after myocardial infarction (MI) was assessed in 533 patients who survived 10 days after MI and were followed for up to 24 months (mean 18) in the Multicenter Investigation of the Limitation of Infarct Size Analysis of multiple clinical and laboratory variables determined before hospital discharge revealed that frequent ventricular premature beats (VPBs) (greater than or equal to 10/hour) on ambulatory electrocardiographic monitoring and left ventricular (LV) dysfunction (radionuclide LV ejection fraction less than or equal to 040) were independently significant markers of risk for subsequent sudden death believed to be the result of a primary ventricular arrhythmia The incidence of sudden death was 18% in patients with both LV dysfunction and frequent VPBs (11 times that of patients with neither of these findings) Seventy-nine percent of all sudden deaths occurred within 7 months after the index MI In 280 survivors reclassified 6 months after MI with regard to the presence or absence of frequent VPBs and LV dysfunction, these risk factors could not be associated with sudden coronary death over a further follow-up period of up to 18 months; the overall incidence of sudden cardiac death was low (14%) after 6 months Thus, the presence of frequent VPBs in association with LV dysfunction early after MI identifies patients at high risk for sudden death over the next 7 months

Homologies between signal transducing G proteins and ras gene products

Abstract: The guanosine triphosphate-binding proteins (G proteins) found in a variety of tissues transduce signals generated by ligand binding to cell surface receptors into changes in intracellular metabolism. Amino acid sequences of peptides prepared by partial proteolysis of the alpha subunit of a bovine brain G protein and the alpha subunit of rod outer-segment transducin were determined. The two proteins show regions of sequence identity as well as regions of diversity. A portion of the amino-terminal peptide sequence of each protein is highly homologous with the corresponding region in the ras protein (a protooncogene product). These similarities suggest that G proteins and ras proteins may have analogous functions.

Sex difference in the effects of sociocultural status on diabetes and cardiovascular risk factors in mexican americans the san antonio heart study

Abstract: The authors postulated that as Mexican Americans became more affluent and/or acculturated to "mainstream" United States life-style they would progressively lose their "obesity-related" pattern of cardiovascular risk factors which were defined as: obesity, diabetes, hypertriglyceridemia and low levels of high density lipoprotein cholesterol. This hypothesis was tested in 1979-1982 in the San Antonio Heart Study, a population-based study on 1,288 Mexican Americans and 929 Anglos living in three San Antonio neighborhoods: a low-income barrio, a middle-income transitional neighborhood, and a high-income suburb. The study population comprised 25-65-year-old men and nonpregnant women. In Mexican American women, all of the "obesity-related" risk factors fell sharply with rising socioeconomic status. In Mexican American men, by contrast, diabetes was the only "obesity-related" risk factor which fell with rising socioeconomic status. Moreover, it fell less steeply, there being an approximately twofold difference in diabetes prevalence between the barrio and the suburbs in men compared to a fourfold difference in women. Also, total and low density lipoprotein cholesterol rose with rising socioeconomic status in Mexican American men, but not in Mexican American women. "Obesity-related" risk factors were generally higher in Mexican Americans of both sexes than in their Anglo neighbors who were of similar socioeconomic status. These results suggest that cultural factors exert a stronger influence on diabetes and cardiovascular risk factors in Mexican Americans than do purely socioeconomic factors.

The hypercalcemia of cancer. Clinical implications and pathogenic mechanisms.

Abstract: HYPERCALCEMIA is one of the most common metabolic complications of cancer. It has fascinated clinicians since it was first recognized 60 years ago by Zondek et al.1 It is now being recognized more ...

Human transferrin: cDNA characterization and chromosomal localization

Abstract: Transferrin (Tf) is the major iron binding protein in vertebrate serum. It shares homologous amino acid sequences with four other proteins: lactotransferrin, ovotransferrin, melanoma antigen p97, and HuBlym-1. Antigen p97 and the Tf receptor genes have been mapped on human chromosome 3. The goal of the study described here was to initiate the characterization of the Tf gene by identifying and characterizing its cDNA and mapping its chromosomal location. Recombinant plasmids containing human cDNA encoding Tf have been isolated by screening an adult human liver library with a mixed oligonucleotide probe. Within the 2.3 kilobase pairs of Tf cDNA analyzed, there is a probable leader sequence encoded by 57 nucleotides followed by 2037 nucleotides that encode the homologous amino and carboxyl domains. During evolution, three areas of the homologous amino and carboxyl domains have been strongly conserved, possibly reflecting functional constraints associated with iron binding. Chromosomal mapping by in situ hybridization and somatic cell hybrid analysis indicate that the Tf gene is located at q21-25 on human chromosome 3, consistent with linkage of the Tf, Tf receptor, and melanoma p97 loci.

Nucleotide sequence of 3-hydroxy-3-methyl-glutaryl coenzyme A reductase, a glycoprotein of endoplasmic reticulum

Abstract: The nucleotide sequence of a 4.8-kilobase mRNA for hamster 3-hydroxy-3-methylglutaryl coenzyme A reductase, the endoplasmic reticulum enzyme that controls cholesterol biosynthesis, shows that it is a protein of 887 amino acids (molecular weight 97,092) which contains three potential sites for asparagine-linked glycosylation. The reductase is a transmembrane glycoprotein, but in contrast to many other transmembrane glycoproteins, it lacks a cleavable or Hydrophobie NH2-terminal signal sequence.

Nutritional status: importance in predicting wound-healing after amputation.

Abstract: Protein-calorie malnutrition, or both, affects the morbidity and mortality of patients undergoing operations. Laboratory assessments of nutritional status consisting of evaluations of serum albumin levels and total lymphocyte counts are valid tests of a patient's nutritional status. In this study we examined the influence of preoperative nutritional status on morbidity in twenty-three diabetic patients who underwent a Syme amputation. All of the patients met Wagner's criteria for a Syme-level amputation, but in only 43 per cent (ten patients) did the amputation heal at this level, which was chosen by Wagner's criteria alone. Of the seven patients who, in addition to meeting Wagner's criteria, had a serum albumin level of at least 3.5 grams per deciliter and a total lymphocyte count of at least 1500 cubic millimeters, in six (86 per cent) the amputation healed at the Syme level. In contrast, the Syme-level amputation healed in only two of the eleven patients who met the criteria of Wagner but who had a serum albumin level of less than 3.5 grams per deciliter and a total lymphocyte count of less than 1500 cubic millimeters.

Prevalence of Diabetes in Mexican Americans: Relationship to Percent of Gene Pool Derived from Native American Sources

Abstract: We have estimated the prevalence of non-insulin-dependent diabetes mellitus (NIDDM) in Mexican Americans and Anglos in three San Antonio neighborhoods. The age-adjusted NIDDM rates (both sexes pooled) for Mexican Americans were 14.5%, 10%, and 5% for residents of a low-income barrio, a middle-income transitional neighborhood, and a high-income suburb, respectively. In Mexican American women, though not in men, obesity also declined from barrio to suburbs. We have previously shown, however, that, although obesity is an important cause of NIDDM in Mexican Americans, there is a two- to fourfold excess in the rate of NIDDM in this ethnic group over and above that which can be attributed to obesity. We therefore speculated that genetic factors might also contribute to excess NIDDM in this ethnic group. The percent native American admixture of Mexican Americans as estimated from skin color measurements was 46% in the barrio, 27% in the transitional neighborhood, and 18% in the suburbs. The NIDDM rates in Mexican Americans thus paralleled the proportion of native American genes. Furthermore, the San Antonio Mexican American rates were intermediate between the NIDDM rates of “fullblooded” Pima Indians (49.9%), who presumably have close to 100% native American genes, and the San Antonio Anglo population (3.0%) and the predominantly Anglo HANES II population (3.1%), both of which presumably have few if any native American genes. The association of genetic admixture with NIDDM rates suggests that much of the epidemic of NIDDM in Mexican Americans is confined to that part of the population with a substantial native American heritage.

Duplication within the haptoglobin Hp2 gene.

Abstract: DNA sequencing shows that the intragenic duplication within the human haptoglobin Hp2 allele was formed by a non-homologous, probably random, crossing-over within different introns of two Hp1 genes, probably in an Hp1F / Hp1S heterozygote.

Concurrent determination of enzymatic activities and substrate concentrations in the melatonin synthetic pathway within the same rat pineal gland.

Abstract: This study details the procedures involved in measuring a number of the componets of indole metabolism within the pineal gland. Tryptophan, 5-hydroxytryptophan, serotonin, N-acetylserotonin, melatonin, 5-hydroxyindoleacetic acid, N-acetyltransferase (NAT) activity, and hydroxyindole-O-methyltransferase activity were measured by a combination of three techniques, which included microassays, radioimmunoassay, and high-performance liquid chromatography. Determination of the melatonin synthetic pathway components within the same gland reduces the number of animals needed for studies and allows correlations between these constituents to be calculated. Very high degrees of correlation (r = 0.91-0.99) are seen between those compounds which exhibit significant rhythms (serotonin, NAT activity, N-acetylserotonin, and melatonin) when group means are compared. When correlations are calculated on a per-animal basis throughout the experiment, moderate to high degrees of correlation (r = 0.57-0.79) are found among those components that exhibit rhythms. However, when correlations are determined on a per-animal basis at each time point, no significant correlations are found. One hypothesis accounting for these differences may be that changes occur in indole metabolism within the same pineal gland over a period of a few minutes.

Ankle diastasis without fracture.

Abstract: Ankle diastasis without associated fracture occurs in a latent form in which the diastasis is detected only by stress radiographs, and in a frank form with the diastasis visible on routine, unstressed radiographs. Whereas latent ankle diastasis requires no reduction and can be treated by cast immobilization, frank diastasis requires anatomical reduction of the ankle mortise. The method of reduction depends upon the particular type of frank diastasis. We have identified four types of frank ankle diastasis without fracture. Type I injuries demonstrate straight lateral fibular subluxation without plastic deformation of the fibula and are best treated by open reduction, removal of any interposed soft tissue, and stabilization with a tibiofibular screw. Type II injuries present with straight lateral subluxation of the fibula due to plastic deformation of the distal fibula and may require a fibular osteotomy for reduction prior to internal fixation. Plastic deformation of the fibula as a cause of ankle diastasis has not been previously reported. The uncommon type III injury consists of posterior rotatory subluxation of the fibula. In type IV injuries the talus is dislocated superiorly, resulting in divergence of the tibia and fibula. Type III and IV injuries can usually be treated by closed manipulation and plaster immobilization. The authors treated four type I and two type II patients by open reduction and internal fixation. Both type II injuries required fibular osteotomy to restore the normal tibiofibular relationship. Good results were obtained in four patients. Fair results secondary to stiffness and pain on activity were present in two patients. All patients maintained anatomical reduction of the ankle mortise following removal of the tibiofibular screw.

Low-Load Prolonged Stretch vs. High-Load Brief Stretch in Treating Knee Contractures

Abstract: This study was designed to compare the results of a traditional method of stretching knee flexion contractures by high-load brief stretch (HLBS) with the results of an experimental method of prolonged knee extension by skin traction, low-load prolonged stretch (LLPS). End range of passive knee extension was measured by standard goniometry. Subjects were 11 nonambulatory residents of a nursing home who had demonstrated gradually progressive bilateral knee contractures. Each subject served as his or her own control with one lower limb receiving LLPS and the other limb receiving HLBS and passive range of motion (PROM). Sequential medical trials were used as the clinical research design. Whether comparing the LLPS limb PROM measurements pretreatment and posttreatment (p less than or equal to .05) or the HLBS to the LLPS limb PROM recordings posttreatment (p less than or equal to .05), the results demonstrated a preference for LLPS in the treatment of knee contractures in the immobile nursing home resident.

Binding Characteristics and Interactions of Depressant Drugs with [35S]t‐Butylbicyclophosphorothionate, a Ligand that Binds to the Picrotoxinin Site

Abstract: [35S]t-Butylbicyclophosphorothionate (TBPT), a cage convulsant with picrotoxinin-like activity, binds to rat brain membranes to a single site with an apparent KD of 25.1 +/- 5.6 nM and a Bmax of 1.40 +/- 0.22 pmol/mg protein. TBPT binding to rat brain membranes was inhibited by a variety of convulsant, depressant, anxiolytic, and anticonvulsant drugs that had previously been shown to inhibit [3H]alpha-dihydropicrotoxinin binding. Depressant drugs such as pentobarbital and the nonbarbiturate (+)etomidate inhibited TBPT binding in an uncompetitive manner. Thus, pentobarbital and (+)etomidate decreased both the affinity and the number of binding sites of TBPT to whole brain membranes. The IC50 values of (+)etomidate (9 microM) and pentobarbital (90 microM) are similar to the EC50 values at which they enhance both [3H]gamma-aminobutyric acid and [3H]diazepam binding in cerebral cortex membranes. RO5-4864, which has recently been shown to be a convulsant, also inhibited TBPT binding (IC50 = 10 microM). These results suggest that TBPT binds to the picrotoxinin site and further supports the notion that the picrotoxinin site is an important modulatory site at the benzodiazepine-GABA receptor-ionophore complex.

Cerebral infarction associated with lupus anticoagulants--preliminary report.

Abstract: Hypercoagulability may contribute to stroke in young adults. Lupus anticoagulants (LA) were identified in six patients (4%) of 145 young adults with cerebral infarction. The clinical features of the 6 patients in this survey plus an additional patient from another institution with LA-associated stroke are presented. Four had systemic lupus erythematosus and 3 had idiopathic LA; all had mild thrombocytopenia. In 2 patients, no other conditions associated with stroke were discovered after thorough evaluation. Recurrent arterial thrombosis occurred in 4 of 7 patients during an average of two years of follow-up. Evidence suggests that inhibition of prostacyclin formation may occur with LA, promoting a prothrombotic state.