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Biomedical subjects

C Brennan

Publications and source records attributed to C Brennan.

65 records · Page 4Linked to original sources
PubMed1991

Assembly of the sea urchin extraembryonic hyaline layer; Ca2+ and Mg2+ act independently and at different sites on the pathway leading to hyalin-gel formation.

We have studied the interactions of Ca2+ with the sea urchin extraembryonic coat protein hyalin. As reported previously, Ca2+ alone was ineffective in inducing hyalin-gel (large aggregate) formation. This reaction required the additional presence of Mg2+ and NaCl. However, the results of tryptic digestion and nondenaturing agarose gel electrophoresis experiments demonstrated that Ca2+ could induce hyalin self-association into small aggregates in the absence of Mg2+ and NaCl. Magnesium did not modulate the interactions of Ca2+ with hyalin. In addition, Mg2+ had minimal effects on the conformation of hyalin. These results have been incorporated into a model delineating the pathway leading to hyalin-gel formation.

Animals↗
PubMed1990

Extrageniculate vision in hemianopic humans: saccade inhibition by signals in the blind field.

The functional competence of extrageniculate visual pathways in hemianopic humans was demonstrated by showing that distractor signals in the blind half of the visual field could inhibit saccades toward targets in the intact visual field. This inhibitory effect of unseen distractors in patients occurred only when distractors were presented in the temporal half of the visual field, was specific to oculomotor responses, and did not occur in normal subjects. These results show that a peripheral visual signal activates retinotectal pathways to prime the oculomotor system and that these pathways can mediate orienting behavior in hemianopic humans.

Analysis of Variance↗
PubMed1990

Cytologic correlates of cervical papillomavirus infection.

A fundamental question in Papanicolaou smear screening is the specificity of cytologic criteria for the recognition of genital human papillomavirus (HPV) infection. To address this problem, we conducted a two-phase study of routinely screened women to determine the efficiency with which cytologic findings identified the presence of HPV DNA, focusing on the criteria for identifying smears as "atypical." In phase 1, 25 of 290 (8.6%) smears were designated atypical, but only 3 (12%) of the samples contained HPV nucleic acids. Four of five (80%) smears designated as diagnostic of HPV/cervical HPV infection were associated with HPV nucleic acids. By applying more stringent criteria for the diagnosis of atypical in phase 2, only 3 of 166 (1.8%) were identified as atypical. Of these, two (67%) contained HPV nucleic acids. The criteria that most efficiently correlated with HPV nucleic acids included prominent nuclear enlargement with either multiple nuclei or nuclear hyperchromatism. On review of the 19 HPV-positive and 20 control HPV-negative smears originally diagnosed as cytologically negative, the above criteria identified an additional 3 cytologically atypical/positive smears versus none (0 of 20) in the control group. This study supports the concept that cytologic abnormalities suggesting "subtle" HPV infection may be extremely difficult to distinguish from non-HPV-related changes, and that criteria used to imply "suggestive but not diagnostic for HPV infection" should be continually reevaluated. The potential role of HPV DNA analysis in Papanicolaou smear interpretation is discussed.

Adult↗
PubMed1987

Vaginal absorption of naproxen.

The vaginal absorption of the drug naproxen was investigated in five healthy pre-menopausal women. It was found that naproxen was absorbed, but not to therapeutically useful levels.

Absorption↗
PubMed1987

Systemic absorption of endotracheally administered aminoglycosides in seriously ill patients with pneumonia.

A study was performed with 10 hospitalized patients to determine the percentage of an aminoglycoside dose (tobramycin or gentamicin) that is absorbed systemically after being instilled into the endotracheal tube at steady state. All patients were on respirators, had indwelling urinary catheters, and had creatinine clearances estimated to be greater than or equal to 40 ml/min. Tobramycin or gentamicin (40 mg) was instilled every 4 h directly into the endotracheal tube. Nine patients also received systemically a different aminoglycoside from that administered through the endotracheal tube. Urine was collected over a 4-h dosing interval at steady state (after at least 5 doses of the drug). The amount of aminoglycoside excreted over the 4-h interval was measured and expressed as percentage of the dose administered over that period. The range of percentage of dose absorbed was 1.5 to 34%, with a mean of 16.7 +/- 11.4% standard deviation and a median of 16.5%. The coefficient of variation was 68%. Levels of the endotracheally administered aminoglycoside in serum were measured, and all were less than 1.0 microgram/ml. While a large degree of variability in absorption was observed in this study, significant amounts of aminoglycosides could be absorbed in some patients. However, levels apparently did not accumulate in sera of patients with adequate renal function, and an empirical dosage reduction in intravenous aminoglycoside should not be necessary with the addition of endotracheally instilled aminoglycoside in patients with creatinine clearances greater than 40 ml/min.

Absorption↗
PubMed1983

Importance of unbound phenytoin serum levels in head trauma patients.

Total (bound + unbound) and unbound phenytoin serum concentrations were measured in ten male comatose head trauma patients and ten male epileptic patients. Serum biochemistry and complete blood cell counts were normal for both groups, except albumin concentrations were below normal in the head trauma patients for nutritional reasons. Total phenytoin concentrations were 6.8 +/- 1.8 mcg/ml for the head trauma patients and 14.5 +/- 3.0 mcg/ml for the epileptic patients (p less than 0.0002) even though phenytoin doses were similar. However, unbound phenytoin concentrations were within the therapeutic range of 1 to 2 mcg/ml for both groups and were not significantly different. Had only the total concentrations been measured, phenytoin doses might have been increased inappropriately in the head trauma patients. The reason head trauma patients had therapeutic unbound concentrations despite lower total concentrations was that the unbound per cent of phenytoin was higher in these patients (21 +/- 3.2%) than in the epileptic patients (10 +/- 1.3%, p less than 0.0002).

Adult↗
PubMedDate not supplied

HIV immunopathogenesis.

The challenges of human immunodeficiency virus type 1 (HIV-1) infection are related to the evolving scientific knowledge that has accumulated regarding the pathogenesis of the HIV illness trajectory. HIV-1 infection results in the clinical presentation of a disease process that encompasses a spectrum of illness from asymptomatic infection to acquired immune deficiency syndrome (AIDS). This article will provide a review of the human immune system, the structure, life cycle, and kinetics of HIV including its effects on the immune system, as well as the transmission, diagnosis, and current treatment recommendations.

Disease Progression↗