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Biomedical subjects

J Thomas

Publications and source records attributed to J Thomas.

At least 631 records · Page 35Linked to original sources
PubMed1985

T-helper cell lymphoma involving the lymph nodes and skin. A clinical, morphologic, and immunohistochemical analysis of five cases.

The clinical, morphologic, and immunohistochemical features of 5 cases of peripheral T-cell lymphoma with lymph node and skin involvement are reported. All patients were male and presented with generalized lymphadenopathy and skin lesions. Lymph node biopsy specimens showed a diffusely growing, pleomorphic, atypical lymphoid infiltrate composed of markedly irregular small and large cells. The stroma consisted of plasma cells, eosinophils, epithelioid histiocytes, and an increased number of small blood vessels. A similar neoplastic infiltrate was observed in the cutaneous nodules that developed in three patients. Immunohistochemistry on frozen tissue sections of lymph nodes using a broad panel of monoclonal antibodies revealed that the neoplastic cells were reactive with anti-T-cell antibodies, the majority of them belonging to the helper/inducer T-cell subset. Stromal plasma cells contained polyclonal immunoglobulins. It is concluded that the malignant lymphoma of peripheral helper/inducer T-cell origin observed in these five patients represents a variant of a mixed, blastic/cell T-cell lymphoma, characterized by a peculiar stromal component and skin involvement.

Aged↗
PubMed1985

The effect of prostaglandin E2 on the initial immune response to herpes simplex virus infection.

Numerous clinical situations, demonstrated to be associated with reactivation of herpes simplex virus infections, have also been shown to produce increases in local levels of prostaglandins. The current study was initiated to determine if prostaglandins play a role in the immune response and control of herpes simplex virus infections. Lymphocytes from volunteers were stimulated with concanavalin A, herpes simplex virus 1, or herpes simplex virus 2 in the presence of prostaglandin E2 or ibuprofen, and the lymphocytes served as their own controls. The data suggest a statistically significant suppression in nonspecific T cell mitogen stimulation (concanavalin A), as well as specific herpes simplex virus 1 and 2 stimulations as measured by tritiated thymidine uptake by lymphocytes when stimulated in the presence of prostaglandin E2. Ibuprofen did not alter the proliferative response to concanavalin A, herpes simplex virus 1, or herpes simplex virus 2 stimulation. This report examines the involvement of prostaglandins in herpesvirus infection such as the suppression of T cell function, allowing for a clinical recurrence. The usefulness of nonsteroidal antiinflammatory agents in the therapy of herpes simplex virus infections is also discussed.

Adolescent↗
PubMed1985

Risk factors and the incidence of hypertension in black physicians: the Meharry Cohort Study.

A prospective longitudinal study of black medical students was conducted to determine the predictive value of hypertension precursors. Follow-up examinations, averaging 22.5 years later, were performed on 341 subjects (78.8%); 25 (5.8%) additional subjects were identified as dead out of 433 original participants. Results are reported on 313 reexamined men. A remarkable 43.8% of the physicians had elevated blood pressure higher than 140/90 mm Hg or gave a history of hypertension and treatment. Correlation coefficients, quintile distributions, and regressions all confirmed the ability of baseline SBP and DBP to predict their respective pressures on follow-up examination. Discriminant function tests yielded baseline SBP, DBP, smoking, and parental history of stroke or hypertension to be the most significant precursors distinguishing hypertensive from normotensive groups, and the model correctly classified 69.7% of the subjects. Baseline cholesterol and Quetelet index levels did not reach statistical significance. The cold pressor test was not predictive but interim weight gain was highly significant. Results are discussed in relation to comparable studies on white populations.

Adult↗
PubMed1985

Lymphocyte subsets in women on low dose oral contraceptives.

Oral contraceptive users have been reported to have a higher incidence of viral, bacterial and fungal infections. This study was undertaken to try to elucidate some of the mechanisms responsible for this increased susceptibility to infection. Peripheral blood lymphocytes were labelled with murine monoclonal antibodies directed against T cells and the various lymphocyte subsets: helper cells, suppressor/cytotoxic cells, or natural killer cells. The lymphocytes were then analyzed on a Coulter Electronics Epics V fluorescent activated cell sorter (FACS). A total of 27 control and 33 oral contraceptive users were studied. In comparison to the control group, there was no significant difference between the two groups in percentage or absolute numbers of total T cells, helper cells, suppressor/cytotoxic cells or natural killer cells. This study suggests that the increase in herpes virus, C. trachomonas, candida, and other infections in women taking oral contraceptives is not related to alterations in the numbers of T lymphocyte subsets or in levels of NK cells.

Contraceptives, Oral↗
PubMed1985

Effects of phenytoin, phenobarbital, and valproic acid, alone and in selected combinations, on schedule-controlled behavior of rats.

The present study examined the effects of phenytoin (20, 30, 40, and 50 mg/kg), phenobarbital (10, 20, 30, and 40 mg/kg), and valproic acid (80, 120, 160, and 240 mg/kg), and those of phenobarbital (10 and 30 mg/kg) combined with phenytoin (20, 30, and 40 mg/kg) or valproic acid (80, 120, and 160 mg/kg), on the lever pressing of rats maintained under fixed-ratio and interresponse-time-greater-than-t schedules of food delivery. High doses of each individual drug significantly decreased mean group response (and reinforcement) rate under the fixed-ratio schedule. No dose of an individual agent significantly affected mean group response rate under the interresponse-time-greater-than-t schedule, although high doses of phenobarbital and valproic acid significantly reduced the mean group reinforcement rate under this schedule. When given in combination, phenobarbital and phenytoin and phenobarbital and valproic acid significantly reduced response (and reinforcement) rate under the fixed-ratio schedule and reinforcement rate under the interresponse-time-greater-than-t schedule. These reductions did not significantly differ in magnitude from those predicted by an additive model of drug interaction.

Animals↗
PubMed1985

Digestion, absorption and utilization of single-cell protein by the preruminant calf. Abomasal outflow and its composition from calves given milk-substitute diets containing varying amounts of either bacterial or yeast protein.

Two experiments of Latin square design, with four Friesian bull calves fitted with re-entrant duodenal cannulas at 4-10 d of age, were made to study the effect of giving varying levels of single-cell protein on the abomasal outflow and composition of digesta. In Expt 1, diets in which 0, 220, 440, and 660 g/kg milk protein were replaced by the bacterial protein Pruteen were compared from 14 d of age. In Expt 2, which began at about 61 d of age, a comparison was made of diets in which 0, 220, 440 and 660 g/kg milk protein were replaced by the yeast protein Toprina. Collection of abomasal outflow was made for 8 h after feeding for 2 d within each 6 d period of the Latin square design experiment. The amount of diet offered daily was 50 g dry matter/kg body-weight 0.75. Polyethylene glycol (PEG), which was used as an indigestible marker, total nitrogen (TN), protein-N (PN), fat, and potassium, sodium and chloride ion outflows were measured together with pepsin (EC 3.4.23.1) and chymosin (EC 3.4.23.4) activities, pH and titratable acidity. In Expt 1 there was little difference in the outflow of liquid digesta between diets and about 0.9 of the dietary PEG was recovered within the 8 h collection period. With increasing amounts of Pruteen in the diet, outflows of TN, PN, fat and Na+ increased, and the pH of digesta increased. However, the volume of 'apparent secretion' into the abomasum (outflow - intake), pepsin activity, chymosin activity, titratable acidity, (outflow of Cl- -outflow of Na+) as a measure of outflow of HCl, and outflows of K+ and of Cl- were reduced. All outflows decreased with the time interval after feeding, except (Cl- -Na+) outflow. In Expt 2, the same trends as in Expt 1 were apparent, but since one calf had to be slaughtered and the experiment had to be analysed as a randomized block, only PN and K+ outflows and pH were significantly affected by dietary treatment, with K+ outflow increasing, rather than decreasing, with increasing concentration of single-cell protein in the diet.(ABSTRACT TRUNCATED AT 400 WORDS)

Abomasum↗
PubMed1985

Digestion, absorption and utilization of single-cell protein by the preruminant calf. The true digestibility of milk and bacterial protein and the apparent digestibility and utilization of their constituent amino acids.

Two experiments of Latin square design were made, each with four Friesian bull calves fitted with re-entrant duodenal and ileal cannulas at 4-10 d of age. The calves were used to study the effect of giving milk-substitutes containing 0, 300, 500 and 700 g bacterial protein (Pruteen)/kg total protein on apparent digestibility of nitrogen fractions and amino acids and true digestibility of 3H-labelled milk protein and 35S-labelled bacterial protein in the small intestine. A third experiment of Latin square design with four intact Friesian calves was used to measure apparent digestibility of nutrients throughout the alimentary tract and retention of N, calcium and phosphorus. At the duodenum, volume of outflow, its pH, and outflow of total-N(TN), protein-N (PN) and non-protein-N (NPN) decreased with time after feeding. At the ileum, volume of outflow and TN outflow were unaffected by time after feeding but PN outflow decreased; NPN outflow at the ileum increased to a maximum 6 h after feeding and then declined. Increased inclusion of Pruteen did not affect the volume of outflow at the duodenum or ileum, but duodenal PN outflow increased. At the ileum, pH values were lower and TN, PN and NPN outflows were higher with increasing concentration of Pruteen in the diet. Apparent digestibility in the small intestine tended to decrease with greater amounts of Pruteen, but was only significant for NPN. Apparent digestibility from mouth to ileum significantly decreased for TN and PN as Pruteen inclusion increased. Amino acid concentration in duodenal outflow, with the exception of that of arginine, reflected intake. The total amount of each amino acid in ileal outflow increased and the apparent digestibility of most amino acids decreased with greater amounts of Pruteen in the diet. Apparent digestibility of nucleic acid-N from Pruteen was very high. True digestibility in the small intestine and between mouth and ileum of 3H-labelled milk protein was high and did not differ between dietary treatments. True digestibility of 35S-labelled Pruteen was low for the milk-protein diet and tended to increase linearly as more dietary Pruteen was included. Dry matter concentration in faeces and a high apparent digestibility throughout the whole alimentary tract of carbohydrates did not differ between treatments.(ABSTRACT TRUNCATED AT 400 WORDS)

Absorption↗
PubMed1985

Simulation of a prolactin-secreting adenoma by an intrasellar craniopharyngioma.

We report here an unusual case of a 21-year-old woman who presented with amenorrhea, galactorrhea, and hyperprolactinemia (66 to 81 ng/ml) secondary to an unsuspected intrasellar craniopharyngioma. The results of preoperative endocrine testing were compatible with the presence of a prolactin-secreting adenoma. Moreover, high resolution computed tomographic scanning revealed an uncalcified hypodense sellar mass that did not enhance after contrast administration, a feature shared by many prolactinomas. This report illustrates that amenorrhea, galactorrhea, mild to moderate hyperprolactinemia, and a sellar mass should not automatically be attributed to the presence of a prolactin-secreting adenoma.

Adenoma↗
PubMed1985

Structure and function of plant cell wall polysaccharides.

Studies of the primary structures of polysaccharides of growing plant cell walls have shown that these structures are far more complex than was anticipated just a few years ago. This complexity can best be appreciated by considering xyloglucan, a hemicellulose present in the cell wall of both monocots and dicots, and rhamnogalacturonan II (RG-II) and rhamnogalacturonan I (RG-I), two structurally unrelated pectic polysaccharides. This realization led us to postulate that cell wall polysaccharides have functions beyond determining the size, shape and strength of plants. Some years ago we demonstrated that oligosaccharide fragments of a branched beta-linked glucan of fungal cell walls can elicit the production of phytoalexins (antibiotics) in plants by inducing the formation of the enzymes responsible for synthesis of the phytoalexins. It has now been ascertained and confirmed by synthesis that the elicitor activity resides in a very specific hepta-beta-D-glucoside. The heptaglucoside has been shown to elicit phytoalexins by activating the expression of specific genes, that is, by causing the synthesis of the mRNAs that encode the enzymes that synthesize phytoalexins. In other words, complex carbohydrates can be regulatory molecules. Further experiments established that oligosaccharide fragments of polysaccharides, produced by acid or base hydrolysis or by enzymolysis of primary cell walls of plants, also evoked defence responses in plants. Subsequently, we learned that defined fragments of polysaccharides, released from covalent attachment within plant cell walls, can function as regulators of various physiological processes such as morphogenesis, rate of cell growth and time of flowering and rooting, in addition to activating mechanisms for resisting potential pathogens. Examples of plant oligosaccharides with regulatory properties (called oligosaccharins) will be described.

Cell Survival↗
PubMed1985

High density mammalian cell growth in Leibovitz bicarbonate-free medium: effects of fructose and galactose on culture biochemistry.

The most commonly used buffering system for mammalian cell cultures is a bicarbonate/CO2 system, which requires CO2 regulators and incubators to supply a constant level of CO2. As a replacement, Leibovitz developed a bicarbonate-free medium, L15, with relatively high levels of certain amino acids in the free base form. We found that a modified form of L15, containing 10 mM-fructose instead of galactose, supported high density growth of Vero and MDCK cells, with maintenance of a stable pH and lactate/pyruvate ratio. We report here investigations of Vero and MDCK cell growth and culture biochemistry at different concentrations of the two carbohydrates. The initial fructose concentration in the medium affected the eventual pH of the medium, the rate of production of lactic acid and ammonia, and the fructose utilization rate. The initial galactose concentration affected the growth rate but did not affect eventual culture pH, the rates of lactate and ammonia production, or the rate of its own utilization. Thus, Leibovitz' formula, modified to contain 10 mM-fructose, appears to yield satisfactory stability of culture pH and the lactate/pyruvate ratio. At all concentrations of galactose tested, the lactate/pyruvate ratio drifted out of the physiological range.

Ammonia↗
PubMed1985

[Behavior of urinary magnesium in comparison with urinary calcium and oxaluria in rats subjected to portacaval anastomosis].

Rats with a portacaval anastomosis are known to be susceptible to develop uric acid stones. The present studies were undertaken to investigate urinary Mg, Ca and oxalate excretion in such rats. We found that their Mg excretion was doubled, Ca excretion tripled, and oxaluria somewhat decreased. The Ca crystallization attributed to the increased Ca2+ in the urine is, therefore, somewhat held in check by the increased presence of Mg in the urine and by decreased oxalates.

Animals↗
PubMed1985

Fatal child abuse: a two-decade review.

The purpose of the present study was to identify demographic variables and medical causes of death associated with child deaths, secondary to abuse, at one pediatric hospital. Abuse and neglect reporting forms, social service records, and autopsy reports were reviewed. A total of 72 known deaths occurred between 1965 and 1984. The majority of children were under two years of age, and the most common cause of death was head trauma. Less than one half of the children who died presented to the emergency department with visible signs of injury. Male abusers outnumbered females; boyfriends of the victims' mothers were the most frequent perpetrators. Emergency department personnel should have a high index of suspicion about abuse in cases of inadequately explained conditions in children. All cases of children who die unexpectedly, or from inadequately explained conditions, should be referred to the coroner, and autopsies should be performed.

Brain Injuries↗