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Biomedical subjects

B Davis

Publications and source records attributed to B Davis.

At least 163 records · Page 9Linked to original sources
PubMed1991

An exploratory study of environmental and medical factors potentially related to childhood cancer.

To determine whether a general-purpose epidemiologic questionnaire can be used in childhood cancer hospitals to identify associations between environmental factors and the major types of childhood cancer, we report the results of the analysis of the data obtained from such a questionnaire. On admission to St. Jude Children's Research Hospital in Memphis, Tennessee, between 1979 and 1986 a questionnaire was administered to 1,270 mothers of patients diagnosed with childhood cancer. Approximately one-half of the children had acute leukemias (n = 629); the remainder had lymphomas (n = 237) or solid tumors (n = 404). Responses to questions regarding the patients' and parents' environmental and medical histories were compared across nine diagnostic categories. Only 5 of 232 variables remained nominally statistically significant (P less than 0.05) after adjusting for confounding by patient or maternal age, year of birth or diagnosis, patient's race, and social class. The variables identified were length of time the patient was breast-fed (chi 2 = 16.1, P = 0.04); having a garden with fertilizers, herbicides, and pesticides (chi 2 = 17.2, P = 0.03); maternal use of sex hormones during the year before the patient's birth (chi 2 = 18.2, P = 0.02); maternal cigarette consumption (chi 2 = 18.0, P = 0.02); and patient contact with persons with cancer (chi 2 = 20.7, P = 0.01). Despite the large number of patients studied, we identified fewer significant variables than would be expected, on the average, under the null hypothesis. We conclude that the data obtained from a general-purpose epidemiologic questionnaire do not provide a useful overview of the association between exposure to environmental factors and several types of childhood cancer.

Breast Feeding↗
PubMed1991

Treatment of pyoderma gangrenosum with cyclosporine: results in seven patients.

The mainstay of therapy for pyoderma gangrenosum has been corticosteroids, but many patients respond poorly. During the past 2 years we have treated seven patients who had pyoderma gangrenosum with cyclosporine after their condition proved resistant to conventional therapy. No evidence of permanent toxicity from cyclosporine was detected and treatment with other immunosuppressive agents was discontinued in five of seven cases. Tuberculosis was reactivated in one patient. Three patients had a remission, three had an intermediate response, and one did not respond. These results indicate that cyclosporine is useful in the treatment of patients with refractory pyoderma gangrenosum and suggest an immune mechanism in the pathogenesis of this disorder.

Adult↗
PubMed1991

Nasal and retrobulbar mass in a cat caused by Pythium insidiosum.

Nasal and retrobulbar infection caused by the Oomycete Pythium insidiosum is described in a cat. The diagnosis was established on three criteria. The staining of broad, sparsely septate hyphal elements in biopsy tissue using a fluorescein-labelled antiglobulin specific for P. insidiosum, detection of antibodies to P. insidiosum by an immunodiffusion test, and isolation of the aetiological agent in pure culture from the biopsy tissue. Treatment with ketoconazole for 6 weeks resulted in clinical improvement, but proptosis of the left eye slowly appeared after the discontinuation of treatment. This case represents a new host for P. insidiosum, namely, a domestic, shorthaired cat, from North Carolina, U.S.A.

Animals↗
PubMed1991

Cigarette smoke in lungs evokes reflex increase in tracheal submucosal gland secretion in dogs.

Stimulation of pulmonary C-fibers (PCs) by capsaicin and of rapidly adapting receptors (RARs) by reduced lung compliance reflexly increases airway submucosal gland secretion in dogs. Because both PCs and RARs are stimulated by cigarette smoke (nicotine being the primary stimulus), we performed experiments in anesthetized open-chest artificially ventilated dogs (with aortic nerves cut) to determine whether cigarette smoke reflexly stimulates airway secretion. We measured submucosal gland secretion by counting the hillocks in a 1.2-cm2 field of tracheal epithelium coated with tantalum dust. Secretion was stimulated by delivery of 40-320 ml smoke from high-nicotine cigarettes to the lower trachea, secretion rate increasing from 7.4 +/- 1.3 to 48.1 +/- 5.1 hillocks.cm-2.min-1. Results of cutting the pulmonary vagal branches or carotid sinus nerves or both indicated that the secretory response was initiated by stimulation of lower respiratory vagal afferents and augmented several seconds later by stimulation of carotid chemoreceptors. Results of cooling the cervical vagus nerves to 7 and 0 degrees C indicated that most of the vagally mediated increase in secretion was due to stimulation of afferent lung C-fibers.

Animals↗
PubMed1991

Neural regulation of lysozyme secretion from tracheal submucosal glands of ferrets in vivo.

To investigate how central and peripheral nerves affect lysozyme secretion from tracheal submucosal glands in ferrets we injected substance P (20 nmol/kg in 200 microliters) intracisternally or intravenously into anesthetized artificially ventilated ferrets. We collected 3-ml samples from a perfused (3 ml/5 min) segment of trachea in situ during 15 min before and 45 min after injection of substance P. Content of lysozyme, a specific marker of tracheal submucosal gland serous cell secretion in ferrets, was measured spectrophotometrically in each sample. Intracisternal substance P increased peak lysozyme output threefold compared with baseline. This increase was abolished completely by cutting both superior laryngeal nerves (SLN) and was partially inhibited by atropine, phentolamine, or propranolol. Intravenous substance P increased peak lysozyme output 10-fold compared with baseline. This increase was partly abolished by cutting both SLN. We concluded that intracisternal substance P stimulated the central nervous system (CNS) and activated cholinergic, adrenergic, and nonadrenergic noncholinergic secretomotor nerves to tracheal glands and that intravenous substance P increased lysozyme secretion both by acting directly on tracheal glands and indirectly on the CNS to activate secretomotor nerves.

Animals↗
PubMed1991

Systolic Hypertension of the Elderly Program (SHEP). Part 10: Analysis.

The SHEP is a randomized, placebo-controlled trial that will follow standard clinical trial principles in analyzing data relating to its proposed hypotheses. The protocol has stated a priori the main objective as well as the secondary subgroup hypotheses. Sample size calculations for SHEP have accounted for dropins to and drop-outs from active therapy as well as for the risk of nonstroke death. The sample size achieved (4,736 participants) should be adequate to address the proposed questions. Monitoring procedures have been described and established. A data and safety monitoring board that uses these procedures is closely following the data from the trial. The board will periodically examine the data to determine whether termination of the study is warranted.

Health Services for the Aged↗
PubMed1991

Influence of lens cortex on postoperative inflammation and cellular deposits on surface of intraocular lenses in rabbit eye.

An animal model was used to evaluate the influence of residual lens cortex on postoperative inflammation and cellular deposits on intraocular lenses (IOLs). Eighteen New Zealand white rabbits underwent bilateral endocapsular phacoemulsification with placement of a one-piece polymethylmethacrylate (PMMA) IOL in the capsular bag. A predetermined amount (15 mg, 30 mg or 60 mg) of homogenized lens cortex was injected into the anterior chamber of one of the eyes of each rabbit after bilateral IOL implantation. The contralateral eye served as the control. The animals underwent slit-lamp examination postoperatively, and the anterior segment of each eye was examined by gross and light microscopy. On slit-lamp examination, the eyes which had received a 60-mg injection of cortex showed a significantly higher amount of posterior synechiae than their contralateral, control eyes. After 2 weeks of observation, the rabbits were sacrificed, the eyes were enucleated, and the IOLs were removed and examined by light microscopy and scanning electron microscopy (SEM). The number of cellular deposits on the IOLs removed from the eyes receiving a 30-mg injection of cortex was significantly larger than that found in their contralateral, control eyes (P less than 0.05), but the eyes in the 60-mg and 15-mg injection groups showed no significant difference between control eyes and IOL eyes in the number of cellular deposits on explanted IOLs. Observation by SEM determined that the filopodia on the epithelioid cells found on the IOLs removed from the eyes in the 60-mg injection group showed an increased number and length compared to their controls. The epithelioid cells on the IOLs of the 30-mg injection group showed an increased number of filopodia compared to their controls.

Animals↗
PubMed1991

Chemicals and environmentally caused diseases in developing countries.

This chapter discusses international aspects of diseases resulting from exposure to chemical pollutants in the environment, with an emphasis on developing countries. These countries share many of the same problems of air, water, and pesticide pollution that face the more industrialized countries. In developing countries, however, the problems are compounded by a number of unique situations, viz., economic priorities, high burden of infectious diseases, impoverishment, and absence of a regulatory framework for the disposal of toxic chemicals. This discussion emphasizes the importance of interactions among toxicants, malnutrition, and infectious diseases for both urban and rural populations insofar as these interactions contribute to disease. Toxicants not only produce disease directly but also exacerbate diseases with other causes. Specific examples from developing countries demonstrate how human health effects from exposures to environmental chemicals can be assessed. While they do not strictly fall under the rubric of "developing countries," the public health consequences of inadequate control of environmental pollution in the East European countries should demonstrate the magnitude of the problem, except that in developing countries the public health consequence of environmental chemicals will be aggravated by the widespread malnutrition and high prevalence of infectious diseases. Much needs to be done before we can adequately quantify the contribution of environmental chemicals to morbidity and mortality in developing countries with the level of sophistication now evident in the charting of infectious diseases in these countries.

Air Pollution↗
PubMed1991

Absence of particle-induced coronary vasoconstriction during cardioplegic infusion: is it desirable to use a microfilter in the infusion line?

Many cardiac surgical units now use a microfilter in the infusion line for delivery of crystalloid cardioplegic solution to protect against the potential hazards of particulate contamination of cardioplegic solution. The aim of this group of studies was to determine the effects of particulate contamination of cardioplegic solutions, in order to establish whether a microfilter is needed in the infusion line. Total particle counts performed on two commercial cardioplegic solutions were low, but there were sufficient particles greater than 10 microns in diameter to cause coronary vasoconstriction. In isolated rat hearts a 20-minute infusion of St. Thomas' Hospital cardioplegic solution produced a progressive reduction in coronary flow, which was not prevented by the inclusion of a 0.8 micron filter in the infusion line. Two studies were performed on canine hearts to determine the effects of unfiltered cardioplegic solution on coronary vascular resistance. In the first, cardioplegic solution at 20 degrees C was infused for 20 minutes at a constant pressure of 50 mm Hg and flow rate was measured. In the second, the same solution at 4 degrees C was infused at a constant flow rate for 2 1/2 minutes and the infusion pressure was measured. In neither study did coronary vascular resistance rise. A final clinical study involving patients undergoing coronary bypass surgery compared the effects on coronary resistance of infusion at a constant flow of filtered versus unfiltered cardioplegic solution (n = 10 in each group). There was a similar rise in coronary perfusion pressure in both groups during the infusion. We conclude that there is insufficient evidence of particle-induced coronary vasoconstriction to justify the expense of a microfilter in the cardioplegic infusion line.

Animals↗
PubMed1990

MMPI differences for renal, psychiatric, and general medical patients.

Renal failure has both medical and psychological implications. Indeed, various psychiatric problems related to end-stage renal disease have been reported in the literature; however, the focus has been on anxiety and depression. While previous research has dealt with the comparisons of patients with renal failure, few studies have investigated the comparison of renal patients with psychiatric and general medical patients. The present study compared renal patients (N = 24) with a group of depressed psychiatric patients (N = 24) and a group of general medical patients (N = 24) on the MMPI. The results suggested that the renal group presented a psychological profile that more closely resembled that of the depressed psychiatric group than that of patients with other chronic medical conditions.

Adaptation, Psychological↗
PubMed1990

Hypothesis validity of clinical research.

Hypothesis validity refers to the extent to which research results reflect theoretically derived predictions about the relations between or among constructs. The role of hypotheses in theory testing is discussed. Four threats to hypothesis validity are presented: (a) inconsequential research hypotheses, (b) ambiguous research hypotheses, (c) noncongruence of research hypotheses and statistical hypotheses, and (d) diffuse statistical hypotheses and tests.

Humans↗
PubMed1990

Human keratinocytes contain carbohydrates that are recognized by keratan sulfate-specific monoclonal antibodies.

Monoclonal antibodies that recognize carbohydrate epitopes found in keratan sulfate glycosaminoglycan chains identified both intracytoplasmic and cell-surface carbohydrates of human keratinocytes. These carbohydrates were detected, using indirect immunoperoxidase methods, both in sections of paraffin-embedded tissues and in intact cultured keratinocytes. Of the seven anti-keratan sulfate monoclonal antibodies used in this study, five detected significant amounts of epitopes associated with keratinocytes. This indicates that only certain, specific types of keratan sulfate-like carbohydrates were expressed by these cells. The extent and localization of keratan sulfate-like carbohydrates appeared to be closely related to the differentiation status of cultured keratinocytes. These epitopes were very weakly expressed on surfaces of all monolayer keratinocytes, but flattened, suprabasal cells in high Ca++ cultures strongly expressed keratan sulfate-like carbohydrates on their surfaces. A much larger population of cultured keratinocytes expressed intracellular keratan sulfate-like carbohydrates identified by the same five antibodies that detected surface epitopes. In monolayer cells, keratan sulfate-like carbohydrates were predominantly found in a broad perinuclear zone. In addition, three of the five immunoreactive antibodies detected epitopes that appeared at cell boundaries, specifically at sites of close cell-to-cell contact. Thus, molecules bearing carbohydrates recognized by anti-keratan sulfate antibodies appear at developmentally important stages of keratinocyte differentiation, indicating that these carbohydrates may serve as markers for molecules important in the differentiation of human keratinocytes.

Antibodies, Monoclonal↗
PubMed1990

Identification of monoclonal antibodies that recognize novel epitopes in native chondroitin/dermatan sulfate glycosaminoglycan chains: their use in mapping functionally distinct domains of human skin.

Five monoclonal antibodies (MAb), 7D4, 4C3, 6C3, 4D3, and 3C5, were produced in mice immunized with high buoyant density embryonic chick bone marrow proteoglycans (PGs) as antigen. All of these MAb recognized epitopes in native chick bone marrow and cartilage PGs which could be selectively removed by chondroitinase ABC and chondroitinase AC II, indicating that their epitopes were present in chondroitin sulfate glycosaminoglycans (GAGs). These MAb recognized epitopes present in purified cartilage PGs obtained from a wide variety of different vertebrate species. However, none of the new MAb detected epitopes in Swarm rat chondrosarcoma PG. On the basis of these results, we propose that these MAb recognize novel epitopes located in chondroitin sulfate/dermatan sulfate glycosaminoglycan (CS/DS GAG) chains, representing at least four and possibly five different structures. Immunocytochemical studies have shown that the epitopes identified by these new MAb are differentially distributed in tissues. All of these MAb immunocytochemically detected epitopes in embryonic chick cartilage and bone marrow. Three of them (4C3, 7D4, and 6C3) recognized epitopes in adult human skin. All three detected epitopes in the epidermis, one (6C3) strongly detected epitopes in the papillary dermis, and two (4C3, 7D4) detected epitopes in the reticular dermis. Immunostaining patterns in skin using the new MAb directed against native CS/DS structures were distinctly different from those obtained using MAb against the common CS isomers. The distribution of these CS epitopes in functionally distinct domains of different tissues implies that these structures have functional and biological significance.

Animals↗
PubMed1990

Estimation of protein intake: comparison of dietary assessment and urinary excretion.

Estimates of dietary intake of nutrients have many problems, and confirmation of these estimates by chemical measurements of excretory products helps to establish their validity. The correlation between urinary amino acid excretion and dietary history of protein intake are reported herein. Diet diaries were kept by and 24-h urine collected from participants in the Trial of Antihypertensive Therapy and Management, a multicenter cooperative trial comparing the effects of drugs and diet on blood pressure control, side effects, and quality of life. The nutritional information was coded and the data stored by the nutritional analyses facility at Albert Einstein College of Medicine. The chemical determinations were done in the laboratories of the Department of Pathology, Izumo, Japan. The correlation between total protein and 3-methylhistidine was r = 0.42 (n = 96). The correlation was similar for animal protein (r = 0.4). These correlations are of the same order of magnitude as those between dietary sodium and urine sodium, and dietary potassium and urine potassium. We conclude that measurement of urinary protein excretion products may be a useful way to estimate dietary protein intake.

Adult↗
PubMed1989

Analysis of transcription initiation in the Panolis flammea nuclear polyhedrosis virus polyhedrin gene.

The nucleotide sequence of the polyhedrin gene of Panolis flammea multiple nucleocapsid polyhedrosis virus (PfMNPV) has been determined. The coding sequences of this gene shared 82% similarity at the DNA level and 88% similarity at the protein level with the polyhedrin gene from Autographa californica (Ac) MNPV. A single nucleotide deviation from the consensus transcription initiation sequence for baculovirus very late genes was identified in the PfMNPV polyhedrin gene. RNA was prepared from Mamestra brassicae larvae infected with PfMNPV and compared with RNA harvested at 24 h post-infection from AcMNPV-infected Spodoptera frugiperda cells using Northern blotting with an AcMNPV polyhedrin gene-specific probe. The PfMNPV mRNA was estimated to be 1.0 kb compared with a larger size of 1.15 kb for the AcMNPV polyhedrin mRNA. A cDNA copy of the 5' end of the PfMNPV polyhedrin mRNA was made using the technique of primer extension and sequenced to demonstrate that the point of transcription initiation was similar to that of AcMNPV polyhedrin mRNA.

Animals↗
PubMed1989

Pulmonary rapidly adapting receptors reflexly increase airway secretion in dogs.

We attempted to determine whether stimulation of pulmonary rapidly adapting receptors (RARs) increase tracheal submucosal gland secretion in anesthetized open-chest dogs. Electroneurographic studies of pulmonary afferents established that RARs but not lung C-fibers were stimulated by intermittent lung collapse during deflation, collapse being produced by removing positive end-expiratory pressure (PEEP, 4 cmH2O) or by applying negative end-expiratory pressure (NEEP, -4 cmH2O). We measured tracheal secretion by the "hillocks" method. Removing PEEP or applying NEEP for 1 min increased secretion from a base line of 6.0 +/- 1.1 to 11.8 +/- 1.7 and 22.0 +/- 2.8 hillocks.cm-2.min-1, respectively (P less than 0.005). After PEEP was restored, dynamic lung compliance (Cdyn) was 37% below control, and secretion remained elevated (P less than 0.05). A decrease in Cdyn stimulates RARs but not other pulmonary afferents. Hyperinflation, which restored Cdyn and RAR activity to control, returned secretion rate to base line. Secretory responses to lung collapse were abolished by vagal cooling (6 degrees C), by pulmonary vagal section, or by atropine. We conclude that RAR stimulation reflexly increases airway secretion. We cannot exclude the possibility that reduced input from slowly adapting stretch receptors contributed to the secretory response.

Afferent Pathways↗
PubMed1989

Is diazepam an antidepressant?

In double-blind sequential study, diazepam was compared with the proven antidepressant moclobemide, in patients with atypical depression. Both agents significantly improved depression ratings over eight weeks of treatment. Diazepam was a significantly better antidepressant than moclobemide at four week, although not at eight weeks. All patients ceased diazepam within one year and none reported withdrawal reactions. These data suggest the need to reconsider that benzodiazepines may be antidepressants and to study their possible antidepressant actions.

Adult↗