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Biomedical subjects

P O'Brien

Publications and source records attributed to P O'Brien.

At least 199 records · Page 11Linked to original sources
PubMed1982

The microvascular architecture of the glandular mucosa of rat stomach.

The circulatory pattern in the gastric mucosa of the rat and relationships of mucosal capillaries to gastric gland cells were investigated. Techniques used included the vascular corrosion cast/scanning electron microscope method, scanning electron microscopy of acid-digested tissues, conventional transmission electron microscopy and in vivo light microscopy. Arterial break-up into capillaries invariably occurs around the base of the gastric glands. The mucosal capillaries are fenestrated and vesiculated, and pass in close proximity to the abluminal aspects of the cells of the gastric glands, particularly the parietal cells. At the apices of the glands, the capillaries form a honeycomb network closely applied to the abluminal aspect of the surface epithelial cells, before draining into infrequent venules which are embedded in a substantial connective tissue sheath. No capillary drainage occurs into these venules deeper in the mucosa. No evidence of either mucosal or submucosal arteriovenous anastomoses was found. Because of the close proximity of the fenestrated mucosal capillaries to the parietal cells and surface epithelial cells and the direction of capillary blood flow, the alkaline tide of the actively secreting parietal cell must be transferred to the abluminal aspect of the surface epithelial cells. The capacity of these cells to secrete HCO3- or to neutralize back diffusing H+ ions would thereby be increased.

Animals↗
PubMed1981

The pharmacodynamics of bucainide (RHC G233): pharmacokinetic parameters and relationship between plasma levels and the effect on the electrocardiogram in the dog.

The pharmacodynamic profile of bucainide dimaleate (RHC G-233) in dogs has been studied. The first observed pharmacologic effect was a change in the ECG pattern (T-wave duration and amplitude) that occurred after an average intravenous dose of 2.7 mg/kg. The average plasma concentration of bucainide was approximately 350 ng/ml. Analysis of data from dogs that received a dual infusion of bucainide indicated that bucainide has an extensive volume of distribution, with an average value of approximately 26 l/kg. An average terminal half-life of 89 minutes was observed. Studies with the radiolabeled drug in rats and dogs also demonstrated the drug's large volume of distribution, and its initial rapid disappearance from the blood. Tissue distribution studies in the rat after administration of the radiolabeled drug showed that bucainide is rapidly taken up by the tissues.

Animals↗
PubMed1980

Urinary proteins as biological markers: bladder cancer diagnosis versus urinary tract infection.

Urine specimens from normal individuals, and from patients with bladder cancer, bladder papillomas and urinary tract infections were assayed for the presence of bladder tumor-related antigens. Ten-fold concentrated urine specimens were reacted in Ouchterlony gel diffusion against various anti-human monospecific antisera. With these antisera urine specimens from normal individuals were distinguished from those from patients with bladder carcinoma as well as bladder papilloma. However, the urine samples from individuals with urinary tract infections showed significant reactivity with many of the monospecific antisera as did specimens from patients with bladder cancer and bladder papilloma. Thus, investigations involved in the assay of bladder cancer biological markers should take the proteinuria associated with urinary tract infection into consideration. The potential importance of detecting tumor-specific components for early diagnosis and treatment of bladder neoplasms is stressed.

Antigens, Neoplasm↗
PubMed1980

Detection of tumor-associated antigens in urine from patients with bladder cancer.

An antiserum was prepared to a hypotonic saline extract of bladder tumor tissue which, after absorption with normal tissues, was used to localize tumor-associated antigens in a Sephadex G-150 elution profile of urine from patients with bladder cancer. A second antiserum was prepared to the urine fraction with tumor-associated antigens. After absorption with normal urine and plasma this antiserum was reacted in gel diffusion and complement fixation assays against urine samples from normal individuals, patients with bladder cancer and patients with proved urinary tract infections. In the gel diffusion assays none of the 23 urine specimens from normal individuals, 37 per cent of the 24 urine specimens from patients with urinary tract infections, 61 per cent of 13 urine samples from patients with papillomas and in situ tumors, and 95 per cent of 30 samples from patients with bladder cancer gave positive precipitin reactions. In complement fixation assays urine from 53 patients with papillomas through grade IV cancers showed a mean 50 per cent complement fixation at 30 micrograms. protein, 29 patients with urinary tract infections showed a mean 50 per cent complement fixation at 150 micrograms. protein and all but 6 urine specimens from more than 30 normal individuals showed 50 per cent complement fixation (mean value) at 140 micrograms. protein. Thus, an antiserum has been produced that may be used in assays for the diagnosis of bladder cancer.

Antigens, Neoplasm↗
PubMed1980

Role of acid-base status in the response of the isolated amphibian gastric mucosa to back diffusion of H+.

The effect of a period of induced back diffusion of H+ on the isolated amphibian gastric mucosa was studied under various conditions. Under standard conditions (HCO3--buffered nutrient solution; 95% O2-5% CO2), passage of an electrical current of 500 microA/cm2 for 15 min from a secretory fluid of pH 2.10 across the mucosal resulted in a decrease of the transmucosal potential difference (PD) of 10.9 +/- 1.9 mV, a decrease of resistance (R) of 48 +/- 26 ogema cm2 and a decrease of short circuit current (Isc) of 18 +/- 7 microA/cm2. Flux of the neutral molecule, erythritol from secretory (S) to nutrient (N) fluid increased by 66% and the active transport of Cl- N lead to S decreased from 2.9 to 1.9 microeq/cm2/hr. With removal of HCO3- from the nutrient fluid and with inhibition of carbonic anhydrase activity the period of back diffusion induced significantly greater change in the electrical measurements than occurred when under standard conditions. This increased effect of back diffusion of H+ was not changed by change of the nutrient fluid pH from 7.20 to either 6.6 or 8.2. Increase of the HCO3- concentration of the nutrient fluid to 35 mM or decrease of the CO2 content of the aerating gas to 1% were associated with significantly less change of the electrical measurements than occurred with standard conditions. These studies support the proposal that the the neutralizing reaction HCO3- + H+ leads to CO2 + H2O plays a central role in the gastric mucosal handling of backing diffusing H+ and suggests that the capacity and poise of the HCO3-/CO2 buffer system is an important determinant of the ability of the mucosa to tolerate luminal acidity.

Acid-Base Equilibrium↗
PubMed1979

Alcoholics Anonymous, alcoholism counseling, and social work treatment.

The authors suggest that the misunderstanding by many social workers of the particular values of Alcoholics Anonymous and the skills of alcoholism counselors can involve alcoholic patients themselves in the stress of reconciling different approaches to treatment. They call upon all who treat alcoholics to build mutual trust and cooperation on two assumptions basic to all forms of treatment-that alcoholism is a disease and abstinence is essential to recovery.

Alcoholics Anonymous↗
PubMed1979

Diabetes insipidus following obstetric shock.

The first known case of obstetric shock followed by diabetes insipidus without anterior pituitary deficiency is presented. A patient developed extreme thirst and polyuria after massive bleeding and prolonged shock due to placenta previa percreta with bladder invasion. Evaluation confirmed diabetes insipidus sensitive to vasopressin administration. Anterior pituitary deficiency could not be identified, either acutely or 6 months later.

Adult↗
PubMed1979

Qualitative analysis of proteinuria associated with bladder cancer.

In the present investigation molecular components associated with the urines from bladder cancer patients and normal individuals are identified. Polyacrylamide gels of urines from bladder cancer, bladder papilloma, and normal individual exhibit clear differences in banding patterns. Urine from bladder cancer patients shows gels with increased quantities of low (less than 100,000) and increased and additional high (less than 100,000) molecular weight proteins when compared to gels with urine from papilloma and normal individuals. In order to localize and identify proteins in the urine from bladder cancer, papilloma, and normal individuals, proteins were separately fractionated on Sephadex G-200 columns and each elution fraction was reacted on Ouchterlony gel diffusion against various specific antisera. The qualitative analysis of proteins in urine from bladder cancer patients is discussed in relation to their molecular weight distribution in the Sephadex G-200 profiles and their possible role in tumor host relationships.

Albuminuria↗
PubMed1978

Cellular adaptations of the ventilatory muscles to a chronic increased respiratory load.

It is not known whether cellular adaptations of the ventilatory muscles are induced by increased respiratory loads. A chronic respiratory load was produced in rats by tracheal banding. Five weeks after the imposition of this increased load, biochemical and histochemical analyses were performed on the diaphragm and intercostal muscles. The oxidative capacity, as indicated by succinate dehydrogenase (SDH) activity, increased 38% in the diaphragm. The capacity for beta-oxidation fatty acids, as indicated by 3-hydroxy-acyl-CoA dehydrogenase (HADH) activity, increased 29%. The glycolytic capacity, as indicated by phosphofructokinase (PFK) activity, did not change. Similar enzymatic adaptations were observed in the intercostal muscles. The proportion of slow-twitch muscle fibers, as indicated by the myofibrillar adenosine triphosphatase (ATPase) stain, increased in the diaphragm, but not in the intercostal muscles. Thus, these ventilatory muscles responded with an increase in their oxidative capacity, and the diaphragm reponded with an increase in the proportion of muscle fibers having the myofibriller ATPase staining characteristic of slow-twich fibers. We conclude that cellular adaptations are induced in the ventilatory muscles by chronic increased respiratory loads.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1978

The pineal gland does not control rod outer segment shedding and phagocytosis in the rat retina and pigment epithelium.

Diurnal patterns of retinal outer segment shedding and phagocytosis by the pigment epithelium were examined in pinealectomized, superior-cervical-ganglionectomized, and sham-operated rats. Phagocytosis was quantitatively similar in all groups. Sharp increases in the number of large phagosomes were observed soon after lights were turned on in the tree sets of animals. Pinealectomized animals kept in constant darkness over a 24 hr period also exhibited normal shedding patterns. Our results suggest that the pineal does not exert a major influence on the daily rhythms of shedding and phagocytosis observed in the retina-pigment epithelium unit.

Animals↗