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Biomedical subjects

B Smith

Publications and source records attributed to B Smith.

At least 379 records · Page 21Linked to original sources
PubMed1985

Nafazatrom-induced salvage of ischemic myocardium in anesthetized dogs is mediated through inhibition of neutrophil function.

The effects of nafazatrom on leukocyte function in vitro and in vivo were related to its ability to salvage ischemic myocardium in an occlusion-reperfusion model of myocardial injury in the anesthetized dog. Nafazatrom (0.4-75 microM) produced dose-related inhibition in vitro of neutrophil aggregation, superoxide anion generation, arachidonic acid metabolism, and, to a lesser extent, the release of beta-glucuronidase. In contrast, nafazatrom (0.4-37.5 microM) did not substantially influence platelet aggregation or the platelet metabolism of arachidonic acid. In vivo nafazatrom (10 mg/kg, po) reduced infarct size from 58 +/- 3% of the risk area (mean +/- SEM, n = 9) in control dogs to 23 +/- 2% of the risk area (n = 9, P less than 0.01). Nafazatrom also reduced the incidence of accompanying arrhythmias. Nafazatrom-induced myocardial salvage was not associated with any hemodynamic changes; moreover, it was independent of platelets, since thrombocytopenia did not prevent nafazatrom from exerting a protective effect. Measurements of the neutrophil-specific myeloperoxidase enzyme in ischemic myocardium indicate that the smaller infarct size in dogs treated with nafazatrom is accompanied by diminished leukocyte infiltration. Thus, the ability of nafazatrom to inhibit neutrophil function in vitro and cell infiltration in vivo may underly its myocardial-protective effects.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1985

Significance of X granules in histiocytosis X: an ultrastructural study.

Histiocytosis X is characterized by the presence of cytoplasmic rod structures called Langerhans' cell granules or X granules (XG). It has been speculated that histiocytosis X is a Langerhans' cell disorder. This ultrastructural study was performed to quantitate the number of XG containing histiocytes in the histiocytosis X lesions. Twenty-four specimens from 22 patients with histiocytosis X were studied: 4 from skin, 5 from lymph node, 11 from bone, 2 from lung, 1 from gingiva, and 1 from cheek. The majority of the histiocytes in histiocytosis X lesions do not contain X granules. The majority of the histiocytes in histiocytosis X lesions do not contain X granules. The percentage of histiocytes with XG in a lesion has no relation to the age of the patient or the organ from which it was obtained, except for skin, where they were quite numerous. The relative percent-age of histiocytes with granules does not correlate significantly with the prognosis of these patients.

Adolescent↗
PubMed1985

Re-examining the tarsal kink syndrome: considerations of its etiology and treatment.

A severe corneal ulceration that is evident shortly after birth and persists in spite of adequate medical therapy, may be secondary to a congenital entropion. A vertically kinked tarsus is an unusual and frequently overlooked form of congenital entropion. Prompt recognition of this entity is essential to avoid severe corneal injury and amblyopia. We present a technique of tarsal stabilization which corrected this upper lid deformity in one case.

Corneal Ulcer↗
PubMed1984

Increased prostacyclin biosynthesis in patients with severe atherosclerosis and platelet activation.

Prostacyclin is a potent vasodilator and platelet inhibitor produced by vascular endothelium. Endogenous production of prostacyclin under physiologic conditions is extremely low, far below the capacity of vascular tissue to generate this substance in response to stimulation in vitro. This may reflect a low frequency or intensity of stimulation of prostacyclin production. We postulated that if prostacyclin does act as an endogenous platelet-inhibitory agent, it should be produced in greater amounts in a clinical setting in which platelet-vascular interactions are likely to be increased. To test this hypothesis, we examined prostacyclin biosynthesis in patients with severe atherosclerosis and evidence of platelet activation in vivo. Excretion of 2,3-dinor-6-keto-prostaglandin F1 alpha, a major urinary prostacyclin metabolite, was significantly higher in 9 patients with severe atherosclerosis and evidence of platelet activation (251 to 1859 pg per milligram of creatinine) than in 54 healthy volunteers (45 to 219 pg per milligram of creatinine; P less than 0.001). This difference represented an alteration in biosynthesis rather than in metabolism, since the fractional conversion of infused prostacyclin to the dinor metabolite was identical in both groups. Prostacyclin production may be low in healthy persons because there is almost no stimulus for its production but enhanced in patients with severe atherosclerosis as a consequence of platelet interactions with endothelium or other vascular insults. These observations are compatible with a role for prostacyclin as a local regulator of platelet-vascular interactions.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Effects of damage to superior colliculi and pre-tectum on movement discrimination in rhesus monkeys.

Eight rhesus monkeys (Macaca mulatta) were trained to detect an instantaneous lateral displacement of a small spot of light. The smallest movement for 79% correct performance was then determined. Severing the splenium of the corpus callosum, which has to be done to reveal the superior colliculi, had no effect on the movement threshold. But when the superior colliculi were damaged in addition, there was an initial substantial impairment in the detection of movement and a smaller but permanent elevation in the threshold. Only if the rostral superior colliculi and pretectum were spared, was there no change in threshold, and there was evidence that the pretectal rather than collicular damage may be more important in relation to movement discrimination. Tests with human observers performing the same task showed that the threshold can be elevated by imprecise fixation and accomodation, suggesting that the consequences of mid-brain damage on movement detection may be wholly or in large part attributed to oculomotor disorders.

Accommodation, Ocular↗
PubMed1984

Protein binding and hepatic clearance: discrimination between models of hepatic clearance with diazepam, a drug of high intrinsic clearance, in the isolated perfused rat liver preparation.

The influence of protein binding on the extraction ratio, and availability, of diazepam has been examined in the single-pass isolated perfused rat liver preparation. Binding of diazepam was varied by adjusting the concentration of albumin in the perfusate. In the absence of binding the extraction ratio of diazepam was high, 0.93-0.995. Extraction decreased dramatically as the degree of binding was increased. The data are more consistent with the "parallel-tube" model than with the "well-stirred" model, two perfusion models that have been used to describe hepatic drug elimination.

Animals↗
PubMed1984

Ultrasonic assessment of endometrial changes in stimulated cycles in an in vitro fertilization and embryo transfer program.

Four distinct patterns in the ultrasonic appearance of preovulatory endometrium can be identified and described in patients undergoing stimulated cycles in an in vitro fertilization program. Ultrasonically, this endometrial response can be seen as a quantitative change in thickness and a qualitative change in gray-scale appearance or reflectivity. The application of this additional parameter of endometrial assessment together with the conventional measurement of follicular diameter as a means of optimally timing oocyte collection has been associated with a reduction in the preoperative ovulation rate from 10.9 to 3.2%, an increase in the fertilization rate from 59.2 to 82.5%, and in a pregnancy rate per embryo transfer of 20.5% in our program without the use of hormonal assays.

Cell Separation↗
PubMed1984

Caffeine and hypertension.

The effect of prolonged caffeine administration on blood pressure in hypertensive subjects was assessed in a double-blind placebo-controlled study. Eighteen hypertensive subjects participated, nine of whom received placebo throughout the study and nine of whom received placebo during the first three days, caffeine during the subsequent seven days, and placebo during the final four days of the two-week study. Those who received caffeine were given 250 mg with meals three times daily. There were no untoward reactions in the course of the study, but one subject with unacceptably high blood pressures while receiving placebo had to be discharged from the study to resume antihypertensive therapy. Systolic blood pressure was immediately increased (9.2 +/- 3.4 mm Hg) within 15 minutes after the first dose of 250 mg of caffeine. On the first day of caffeine, systolic pressure was increased a mean of 7.3 +/- 4.0 mm Hg, but this was no longer significant after the initial day of caffeine administration. Diastolic pressure showed a trend toward increasing, but this never reached significance. The minor increases in plasma catecholamine levels and plasma renin activity were not significant on either a short- or long-term basis. After discontinuation of caffeine, no overshoot phenomena were observed. It is concluded that prolonged administration of caffeine is not associated with significant elevation in blood pressure, plasma catecholamine levels, or plasma renin activity in patients with borderline hypertension.

Adult↗
PubMed1984

Eyelid and orbital treatment following radical maxillectomy.

Malignant lesions of the nasopharynx and paranasal sinuses often encroach upon the orbit. A series of nineteen patients who underwent partial or radical maxillectomy is presented to summarize the eyelid and orbital findings that required further treatment. Fifteen of these patients were left with an intact globe and a visually useful eye, but the defects of epiphora, eyelid malposition, dacryocystitis, and diplopia were visually threatening and required treatment. The cosmetic deformities and diplopia following maxillectomy and radiation are partially amenable to treatment with late bone grafting. Lacrimal outflow deficiencies were successfully treated with dacryocystorhinostomy. Only patients with ocular complications following maxillectomy are included in this series; therefore, the range of problems and their treatment confronting the ophthalmologist is summarized.

Adenocarcinoma↗
PubMed1984

Antibody responses to toxic-shock-syndrome (TSS) toxin by patients with TSS and by healthy staphylococcal carriers.

Serum samples taken from women with toxic-shock syndrome (TSS) and from women without a history of TSS were examined for the presence of antibodies to toxic-shock-syndrome toxin (TST). Serum samples from 38 women with TSS and from 70 women with no history of TSS were analyzed by radioimmunoassay (RIA) and by an enzyme-linked immunoadsorbent assay (ELISA). Antitoxin titers obtained by the assays were highly correlated. Antibody levels in sera of women with TSS, or a history of TSS, were significantly lower than levels in sera of women with no prior evidence of TSS. The mean level of antitoxin titers in the total sample of acute, convalescent, and recovered TSS groups was significantly lower than that of the control groups, which consisted of 31 carriers of genital Staphylococcus aureus and a similar number of age- and race-matched noncarriers. Although a trend toward elevated antitoxin titers was apparent after recovery, no vigorous immunologic response to TST was noted. In contrast, the majority of healthy women demonstrated measurable antitoxin titers, a finding indicative of current or prior colonization with TST-producing strains of S. aureus. The data suggest that absence of antibodies to the TSS toxin may be a predisposing factor in the development of clinical disease.

Antitoxins↗
PubMed1984

Volkmann's contracture of the extraocular muscles following blowout fracture.

In the past decade there has been considerable controversy over the surgical indications for treatment of blowout fractures of the orbit. It has been well recognized that some fracture patients develop an ischemic contracture of the inferior rectus muscle. We have found that a Volkmann's type of contracture of the inferior rectus muscle does exist and is similar to that found in the distal extremities. A specific group of fracture patients is at greater risk for development of a contracture. Elderly patients, hypotensive patients, patients with small fractures, and those with high inferior rectus compartment pressures are more prone to developing a contracted extraocular muscle. We have measured compartment pressures in 18 patients who were surgical candidates following orbital fracture. Our conclusions indicate that surgical intervention following blowout fractures in these high-risk patients may be more prudent than medical management. Patients with persistent diplopia due to a contracted inferior rectus are extremely difficult to treat many months after fracture. We still believe it prudent to surgically repair orbital fractures in patients with diplopia, enophthalmos, and a risk for muscle contracture. The documentation of this additional sequela of unrepaired fractures lends more strength to this belief. There is no evidence to indicate that a Volkmann's contracture would be possible after early repair of a blowout fracture.

Adolescent↗
PubMed1984

Muscle pressure and flow during expiration in infants.

The postinspiratory activity of the inspiratory muscles (Pmusl) was estimated in 12 infants (2 to 4 days old) by analysis of the rise in mask pressure after airway occlusion at end inspiration. We reasoned that if at the end of inspiration Pmusl instantaneously ceased, the mask pressure would immediately increase to the relaxation pressure value corresponding to that volume. Any delay would suggest some degree of Pmusl. In 9 infants, Pmusl reached zero before the end of an average expiration (TE), although lasting for a long portion of TE (83% +/- 25 SD). We then compared the expiratory tidal flow-volume curves during resting breathing with the curves of "relaxed" expirations. In general, the tidal curve shows a linear portion that can be extrapolated to zero flow. From this extrapolation it is apparent that the end-expiratory level (FRC) is above the resting volume of the respiratory system (Vr), the FRC-Vr difference averaging 3.11 ml/kg. In 6 infants, the tidal expiratory flow-volume curve was displaced to the left of the "relaxed" curve, whereas in the remaining infants the two curves superimposed. These analyses suggest that in infants during tidal breathing (1) Pmusl can substantially contribute to the rise in FRC, and (2) the final portion of expiration is in most cases "relaxed." In some infants, however, a braking mechanism, probably of laryngeal origin, further decreases the expiratory flow and may contribute in maintaining the mean lung volume elevated.

Functional Residual Capacity↗
PubMed1984

Effectiveness of cefotaxime in gram-negative meningitis.

We treated 12 adult patients who had gram-negative bacillary meningitis with cefotaxime administered intravenously at a dose of 2 g every 4 hours. The etiological organisms included Haemophilus influenzae (3 cases), Serratia marcescens (3 cases), Klebsiella pneumoniae (3 cases), Escherichia coli (2 cases), and Enterobacter (1 case). The infection followed a neurosurgical procedure in 6 cases. The mean inhibitory and bactericidal concentrations of cefotaxime for the isolates ranged from 0.125 to 0.25 microgram/ml. The cerebrospinal fluid (CSF) concentrations of cefotaxime ranged from 5.0 to 15.2 micrograms/ml, and the CSF bactericidal titers were 1:64 to 1:128. The CSF in all patients was sterilized within 96 hours. All 12 patients recovered, and there were no relapses.

Adult↗