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Biomedical subjects

C Johnson

Publications and source records attributed to C Johnson.

At least 595 records · Page 33Linked to original sources
PubMedDate not supplied

Lack of CCK-like pancreatic stimulation by intraduodenal amino acids in the anesthetized cat.

We have attempted to demonstrate a pancreatic secretory response to intraduodenal amino acids in the anesthetized cat. In four cats stimulated with supramaximal doses of secretin, protein concentrations in pancreatic juice were measured after intraduodenal bolus injection of various amino acids, IV CCK, or electrical stimulation of the vagus nerve. In addition, the duodenum was perfused with phenylalanine (50 mM) for 30 min in two cats, and the vagus nerve stimulated electrically for 15 min in one. In no case did amino acids produce pancreatic protein secretion, whereas CCK and vagal stimulation always did so. We conclude that this insensitivity to amino acids in the cat is a species difference from the dog and man.

Amino Acids↗
PubMedDate not supplied

Testicular toxicity of the transferrin binding radionuclide 114mIn in adult and neonatal rats.

Adult (70 d) and neonatal (7 d) male rats were dosed (i.p.) with 37 MBq/kg (1 mCi/kg; approximately 1 microgram elemental indium/kg) 114mIn, a transferrin-binding radionuclide. In adults, approximately 0.25% of the injected activity localised within the testis by 48 h postinjection and remained constant for up to 63 d. In neonates, 0.06% of the activity was in the testis by 48 h, and this declined such that by 63 d only 0.03% remained. At 63 d, treated rats had reduced sperm head counts and abnormal testicular histology that was more marked in animals dosed as adults than as neonates. In vitro, uptake of 114mIn into seminiferous tubules isolated from 7-, 20-, or 70-d-old rats was compared with that of 125I. Both radionuclides were readily accumulated by the tubules. Whilst 114In uptake into 20- and 70-d tubules was inhibited by excess transferrin, uptake into 7-d tubules was unchanged. 125I uptake was not affected by excess transferrin. These data support the contention that some radionuclides may cross the blood-testis barrier by utilisation of the physiologic iron-transferrin pathway, which may lead to greater testicular damage in adult compared to neonatal animals.

Animals↗
PubMedDate not supplied

Behavioral evaluations in developmental toxicity testing: MARTA survey results.

During 1991, the Middle Atlantic Reproduction and Teratology Association (MARTA) conducted a survey of laboratories performing behavioral evaluations as part of GLP developmental toxicity studies. This survey was conducted to determine the extent to which an "industry standard" had evolved for behavioral test batteries. The most commonly used developmental parameters were eye opening, pinna unfolding, and sexual maturation (physical landmarks); surface righting, pupil constriction, and nonautomated acoustic startle (reflexive landmarks). Locomotor activity was used by 80% of the laboratories. The majority (76%) of laboratories conducted at least one learning and/or retention evaluation; nearly one-fourth of the laboratories routinely performed two. The most common learning tests were watermaze (primarily a simple two-choice discrimination task) and passive avoidance. Automated startle paradigms (habituation, prepulse modification, and/or startle elicitation) were evaluated by 28% of the laboratories. This survey showed a remarkable similarity in methodology across laboratories and a progressive increase in the number of GLP studies that included behavioral assessments. The results indicate that behavioral tests have become a common component of developmental toxicity assessments of pharmaceuticals.

Animals↗
PubMedDate not supplied

Trial of labor: a study of 110 patients.

STUDY OBJECTIVE: The purpose of the study was to determine whether epidural analgesia is unsafe for trial of labor (TOL). DESIGN: Retrospective chart review. SETTING: Inpatient obstetric department at a university medical center. PATIENTS: One hundred ten ASA physical status I and II term parturients who attempted a TOL between December 1987 and June 1988. INTERVENTIONS: All the parturients previously had low transverse uterine incisions and received continuous electronic fetal and uterine pressure monitoring throughout labor. All the parturients were offered epidural analgesia during labor with bupivacaine 0.25%. MEASUREMENTS AND MAIN RESULTS: Sixty-seven percent of the parturients had successful vaginal delivery. Fifty-one of the 110 parturients had epidural analgesia for labor. There were two complete uterine ruptures; neither had epidural catheters. Both of the complete ruptures presented with monitored fetal distress rather than abdominal pain. Both mothers and their infants recovered uneventfully. CONCLUSIONS: Uterine rupture presents as monitored fetal distress rather than abdominal pain. Thus, epidural analgesia can be used in patients attempting a TOL.

Analgesia, Epidural↗
PubMedDate not supplied

Reduced membrane protein methylation in red cells of the McLeod blood group phenotype.

Red cells (RBCs) contain an abundance of protein methylase II, which catalyzes the transfer of methyl groups from S-adenosylmethionine to carboxyl groups of aspartyl and glutamyl residues in proteins. Enzyme-catalyzed transfer of methyl groups, labeled with 14C or 3H, from S-adenosylmethionine to membrane proteins of McLeod, Ko, and control RBCs was assayed by determining the acceptance of labeled methyl groups under standardized conditions. Membranes of control cells and Ko cells showed about 50 percent greater uptake than did those of McLeod cells. However, when ovalbumin was used as a methyl-accepting substrate, the levels of protein carboxymethyltransferase activity in all three types of cells were found not to differ significantly. In addition, no significant qualitative differences were apparent when methyl-labeled polypeptides from control and McLeod cells were separated by slab gel electrophoresis. The mechanisms responsible for changes in membrane protein methylation of McLeod cells remain unclear. However, these observations provide further evidence of the pleiotropic biochemical lesion associated with the acanthocytic morphology that characterizes McLeod RBCs.

Erythrocyte Membrane↗
PubMedDate not supplied

Maternal blood lead level during pregnancy in South Central Los Angeles.

Twenty-five years of public health efforts produced a striking reduction in lead exposure; the blood lead average in the United States has decreased to less than 20% of levels measured in the 1970s. However, poor minority groups that live in large urban centers are still at high risk for elevated lead levels. In this study, our data showed that pregnant immigrants (n = 1,428) who live in South Central Los Angeles--one of the most economically depressed regions of California--have significantly higher (p < .0001) blood lead levels (geometric mean = 2.3 microg/dl [0.11 micromol/l]) than 504 pregnant nonimmigrants (geometric mean = 1.9 microg/dl [0.09 micromol/l]). The most important factors associated with lower blood lead levels in both groups were younger age; more-recent date of blood sampling (i.e., decreasing secular trend); and blood sampling in mid-autumn, instead of mid-spring (i.e., seasonal trend). Blood lead levels of immigrants were strongly dependent on time elapsed since immigration to the United States; each natural log increase in years of residence was associated with an approximately 19% decrease in blood lead levels. Although blood lead means for both groups were almost the same as the estimated national average, 25 of the 30 cases of elevated blood lead (i.e., > or = 10 microg/dl [0.48 micromol/l) occurred in the immigrant group. The odds ratio (95% confidence intervals within parentheses) for having elevated blood lead levels (a) was 9.3 (1.9, 45.8) if the immigrant engaged in pica; (b) was 3.8 (1.4, 10.5) if the immigrant had low dietary calcium intake during pregnancy; and (c) was .65 (.43, .98) for every natural log unit increase of years of residence in the United States. The control of pica and dietary calcium intake may offer a means of reducing lead exposure in immigrants.

Adolescent↗
PubMedDate not supplied

Blood lead level and blood pressure during pregnancy in South Central Los Angeles.

In many studies in which the relationship between blood pressure and blood lead level has been examined, investigators have found significant--but small--associations. There was only one previous report of a significant association of blood lead with blood pressure in pregnant women. We measured blood lead level and sitting blood pressure of 1,627 women in their third trimester of pregnancy. We eliminated subjects with known causes of hypertension. Most women (98.4%) were normotensive. We controlled for body mass index, age, and stress--among other factors--and constructed multiple-regression models of lead association with diastolic and systolic blood pressures. Immigrants (73% of total) had significantly higher blood lead levels and different blood pressures than nonimmigrants, suggesting that analysis be stratified by "immigrant, nonimmigrant" status. Positive relationships between blood lead level and blood pressure were found only for immigrants (p < or = .001). From the 5th to 95th blood-lead percentiles (0.9-6.2 microg/dl) in immigrants, systolic blood pressure increased 2.8 mm Hg, and diastolic blood pressure increased 2.4 mm Hg. Higher prior lead exposure of immigrants (97.7% from Latin countries) than nonimmigrants might explain the differential effect of these low levels of blood lead on blood pressure in nonimmigrants. Perhaps some immigrants are at higher risk than nonimmigrants for lead-associated elevated blood pressure during pregnancy, despite blood lead levels within the currently considered acceptable range.

Adult↗
PubMedDate not supplied

Genetics of red body polymorphism in the isopod, Venezillo evergladensis.

A red body morph with reddish-orange body and brownish-red eyes is described in the terrestrial isopod, Venezillo evergladensis. The alternate, non-red morph, has a brown body and black eyes and either gray or orange antennae. Breeding results show three alleles, rg, ro and r at an autosomal locus control the variation. The dominance hierarchy is rg less than ro less that r; the genotypes, rg/rg, rg/ro, and rg/r are non-red, grey, ro/ro and ro/r are non-red, orange, and r/r are red. The gray antennae of non-red, gray individuals is variable in expression although still objectively recognized. The red body morph and its inheritance is paralleled in related species, while the antennal variation identifies a new allele. Sperm storage, exceeding a full year, and multiple matings in nature are documented.

Animals↗
PubMedDate not supplied

Serum autoantibodies in patients with sickle cell anemia.

The prevalence of serum autoantibodies was determined in 50 black adult patients with sickle cell anemia, and in 33 age- and sex-matched healthy black individuals. Twenty-seven of the patients (54%) had at least one type of autoantibody, in contrast to only four (18.2%) of the control subjects (P less than .01). Antismooth muscle, antiskeletal muscle and antinuclear antibodies were the most frequently seen autoantibodies. There was no correlation between the presence of autoantibodies and history of hepatitis, number of blood transfusions or concurrent drug therapy. Sickle cell anemia is associated with the induction of autoimmune phenomena.

Adult↗
PubMedDate not supplied

Computed tomography of partial unilateral agenesis of the pectoralis muscles.

The most common congenitally absent muscles are the pectoralis major and minor. Absence is usually incomplete. This anomaly is often one component of a syndrome associated with other hand (Poland syndrome) and thoracic anomalies. Computed tomography can identify partial absence of the pectoralis muscle and exactly define the altered anatomy. A patient with myasthenia gravis and isolated partial agenesis of the pectoralis muscle is presented.

Adult↗