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Biomedical subjects

R Baker

Publications and source records attributed to R Baker.

At least 487 records · Page 27Linked to original sources
PubMed1980

What is involved in endoscopic sphincterotomy for gallstones?

This study reports our first year's experience of endoscopic sphincterotomy for common bile duct stones. Forty patients were considered for the procedure and it was attempted in 37. An effective endoscopic sphincterotomy was eventually achieved in 32 (86 cases per cent), 7 after a "pre-cut". Twenty-three patients passed stones spontaneously (72 per cent), 6 could not be reassessed and 3 still had stones present (9 per cent). Bed occupancy was 9.5 +/- 5.9 days. Complications occurred in 30 per cent, the most common being pancreatitis in 6 cases with 1 death. It is concluded that endoscopic sphincterotomy offers a valuable alternative to surgery in the management of common bile duct stones.

Adult↗
PubMed1980

Eye movement related activity and morphology of second order vestibular neurons terminating in the cat abducens nucleus.

Intracellular records were obtained from axons of second order vestibular neurons in, and around, the left abducens nucleus in alert cats implanted with stimulating electrodes on both vestibular nerves and the left VIth nerve. Twelve secondary vestibular neurons were identified by their increase in firing rate with horizontal head rotation to the left and/or increasing eye position to the right. Following HRP injection, somatic location, axonal trajectory and termination sites were determined. Each of the above cells collateralized extensively in the abducens nucleus in a fashion consistent with their being either inhibitory (n = 7; left) or excitatory (n = 6; right) vestibular neurons in the disynaptic horizontal vestibulo-ocular reflex pathway. These vestibular neurons also arborized extensively in other posterior brainstem eye-movement related areas as well as sending an axon to the spinal cord.

Abducens Nerve↗
PubMed1980

Complications associated with surgical repair of urethrovaginal fistula.

We present 4 patients seen in the last five years with urethrovaginal fistulas involving the mid or proximal urethra. Our experience in the transvaginal repair of these fistulas has been disappointing. The best chance for the development of a functioning continent urethra is by suprapubic bladder flap technique or bladder tube replacement with suprapubic urinary diversion. We suggest that no urethral catheter be placed. Complications following surgical repair have been fistula recurrence, urethral shortening and retraction, persistent reflux, bladder calculi, and bladder cancer.

Adult↗
PubMed1980

The effect of halothane on mice selectively bred for differential sensitivity to alcohol.

We have investigated the response of mice to halothane that have been selectively bred for either sensitivity (long sleep, LS) or resistance (short sleep, SS) to the anesthetic effects of ethanol. While large differences in the response of the animals to ethanol were observed in sleep time, blood anesthetic concentration at time of awakening, and body temperature, the SS and LS lines did not differ in their response to halothane. We conclude that the mechanism of action of ethanol and halothane differ in a significant way from each other.

Animals↗
PubMed1980

Acute effects of albumin infusion on blood volume and renal function in premature infants with respiratory distress syndrome.

The purpose of this study was to determine the acute effects of albumin infusion on blood volume and renal function in preterm infants with RDS and low total serum protein values. Ten infants (gestational age 28 to 36 weeks, body weight 0.88 to 2.46 kg) were given albumin 1 gm/kg (as 25% iv solution) over a ten-minute period. Within ten minutes after infusion was completed, total serum protein concentration, colloid osmotic pressure, and blood volume rose significantly while hematocrit fell from their preinfusion levels (P < 0.0005). Mean arterial blood pressure showed a smaller and less clear-cut increase (P < 0.05). Creatinine clearance rose significantly with infusion; even though preinfusion clearances correlated poorly with gestational age (r = 0.43), postinfusion clearances correlated well (r = 0.92). No significant rises in urinary flow rate Uosm/Posm, or free-water clearance were observed. These results indicate that albumin infusion acutely increases both blood volume and glomerular filtration in premature infants with RDS.

Albumins↗
PubMed1980

Observations on the eosinophilic granules in the dorsal papillae of the dog tongue.

The granules from epithelium of filiform papillae of the dorsal surface of dog tongue were characterized as eosinophilic in contrast to the classically described basophilic keratohyalin granules which stain characteristically with hematoxylin. The eosinophilic granules also stained with Sakaguchi oxine reaction indicating the presence of arginine. At the ultrastructural level the round or oval granules varied in size and electron density. The granules were often associated with ribosomes and/or tonofilaments and were not limited by membranes. These granules disappeared in the superficial layers of epithelium which was parakeratotic in nature. Our studies indicate that the eosinophilic granules belong to the class of keratohyalin granules which are known to be heterogeneous in their morphology and biological composition.

Animals↗
PubMed1980

Localization and morphology of cat retractor bulbi motoneurons.

1. Motoneurons innervating the cat retractor bulbi muscle have been identified by retrograde axonal transport of horseradish peroxidase (HRP). Following injections of the four slips of the retractor bulbi muscle, labeled motoneurons were found in the abducens nucleus overlapping the distribution of lateral rectus motoneurons and in the oculomotor nucleus partially overlapping the distribution of medial rectus motoneurons. Retractor bulbi motoneurons also were found in the accessory abducens nucleus situated ventral and lateral to the abducens nucleus. 2. Retractor bulbi motoneurons varied considerably in shape and size, but in all instances contained similar cytoplasmic organelles. Quantitative analyses of mean soma diameter indicated that the average size of retractor bulbi motoneurons was larger than the average size of lateral rectus and medial rectus motoneurons. 3. Retractor bulbi motoneurons in the accessory abducens nucleus were identified electrophysically and stained by intracellular injection of HRP. Neuronal reconstructions demonstrated a dorsomedial axonal trajectory directed toward the abducens nucleus and elongated dendritic fields oriented in a dorsomedial-ventrolateral axis. Another major dendritic extension was directed toward the magnocellular division of the spinal trigeminal nucleus, a major source of excitatory input to these motoneurons. 4. Quantitative analyses of synaptic density indicated that the somata of retractor bulbi motoneurons were contacted by significantly fewer synaptic endings than the somata of motoneurons in the abducens nucleus. Retractor bulbi motoneurons in the abducens nucleus exhibited variations in synaptic density that were similar to the densities on lateral rectus motoneurons. 5. Given the morphological differences in location, size, and somadendritic extent between motoneurons in the accessory abducens, abducens and oculomotor nuclei, it is suggested that such features reflect functional differences between the motoneurons with respect to fiber composition of the muscles they innervate, and subsequently to the role each muscle plays in eye movement. 6. Since the morphological features of retractor bulbi motoneurons in the accessory abducens nucleus are quite different from those in either the abducens or oculomotor nuclei, it appears that each motoneuronal population may perform unique oculomotor functions.

Abducens Nerve↗
PubMed1980

Psychological changes following surgery for tumors in the temporal lobe.

Twenty patients with a tumor in the temporal lobe underwent extensive neuropsychological testing pre- and postoperatively, with special regard to verbal and nonverbal memory. All patients had bilateral abnormalities preoperatively. Contralateral functions tended to improve after surgery, contrary to the outcome expected in patients with bilateral abnormalities due to atrophic lesions. Computerized tomography was the most useful neurodiagnostic test in correctly identifying the nature of the lesion in these patients.

Adolescent↗
PubMed1979

Endogenous prostaglandins and stimulated gastric secretion in the cat: the effect of various secretory inhibitors.

1. The effects of cimetidine, somatostatin and atropine upon the outputs of acid, pepsin, prostaglandins (PG) E and F in gastric juice secreted in response to i.v. infusions of pentagastrin and histamine (H) have been studied in the conscious gastric fistula cat. 2. At constant rate infusions secretion of PGE occurs and follows a similar pattern to that of gastric acid. However the ratio of H:PGE varies considerably and to an extent inexplicable in terms of assay variation. 3. Inhibition of acid output is matched by inhibition of the output of PGE, but changes in concentration of PGE suggest this is a volume related phenomenon. 4. It is concluded that gastric juice PGE is most unlikely to have a regulatory effect upon acid secretion.

Animals↗
PubMed1979

Endogenous prostaglandins in peptic ulcer disease.

Plasma concentrations of prostaglandins E and F have been measured by radioimmunoassay in patients undergoing diagnostic upper intestinal endoscopy. The results fail to support a previously reported deficiency of plasma PGE in duodenal ulcer patients. Plasma prostaglandin concentrations failed to correlate with the parameters of gastric secretion studied; and were unaffected by histamine H2-receptor blockade or the activity of duodenal ulceration. During combined pentagastrin and insulin secretory studies there was a significant correlation between the outputs of PGE and acid into gastric juice.

Adolescent↗
PubMed1979

Immunodiffusion studies of ribosomes in classification of mycobacteria and related taxa.

Ribosomal preparations consisting of crude ribosomes (CR), 30S subunits (30S) and 16S core particles (16S) from four strains of the species Mycobacterium bovis (BCG), Mycobacterium fortuitum, Mycobacterium phlei and Mycobacterium smegmatis were analyzed by immunodiffusion technique for taxonomical purposes. The ribosomal preparations tested contained several interspecies cross-reacting precipitinogens. The number of precipitinogens demonstrated at the homologous reactions was generally larger than the number of precipitinogens shown at the heterologous reactions indicating a probable presence of species-specific antigens in ribosomes. The largest number of possible species-specific precipitinogens was demonstrated when crude ribosomal preparations were studied. However, such precipitinogens were also shown in the 30S subunits and they were individually analyzed. The 16S core particles were dominated by cross-reacting precipitinogens. The number of ribosomal precipitinogens shared by M. phlei and M. smegmatis was large indicating a close taxonomical relationship between these two species. Apart from the four mycobacterial strains studied, 15 other strains representing the genera Mycobacterium, Arthrobacterium, Corynebacterium, Kurthia, Nocardia and Rhodococcus were included in the study. The presence of intergenerically cross-reacting precipitinogens in the ribosomal preparations was demonstrated.

Antigens, Bacterial↗
PubMed1979

Immunodiffusion studies of various structural preparations from mycobacterial cells.

Various structures and other preparations from mycobacterial cells were analyzed by immunodiffusion. The preparations were obtained from four strains referred to the species Mycobacterium bovis (BCG), Mycobacterium fortuitum, Mycobacterium phlei and Mycobacterium smegmatis. They represented cell walls (CW), culture filtrates (CF), artificially disintegrated cell material (XP), protoplasms (PP), crude ribosomes (CR), ribosomal 50S subunits (50S), ribosomal 30S subunits (30S), ribosomal 16S core particles (16S) and ribosomal-free fractions (UCS). The preparations were analyzed by reference precipitation systems based on CF, CR and 30S preparations. Serological comparisons were made with material from the same species and cross-testing between material from different species was not performed. It was shown that from the precipitinogenic point of view the CF and XP materials were very similar and that they both contained protoplasmic material to a large extent. Furthermore, it was found that ribosomal precipitinogens constitute an important part of the precipitinogens in PP as well as in the CF and the XP preparations. The ribosomal precipitinogens were found to represent the two subunits as well as the 16S core particle. One ribosomal precipitinogen, designated beta, was shown in all preparations except the CW and the UCS.

Antigens, Bacterial↗
PubMed1979

Ultrafast laser scanner microscope.

Advances in monolayer deposition of cervical cells have removed one of the last serious obstacles to the design of high-resolution automated diagnostic assessment systems. In this article, we describe the design considerations for a system that is capable of acquiring, within 60 sec, a 0.5 micron digitized image of a 4 cm2 area on a standard glass slide. The most feasible approach is found to be a system using a rotating polygon to sweep the focused spot from a laser across a 2-mm scan line while the slide is uniformly translated perpendicular to the scan direction the use of laser sources (a helium-neon laser at 632 nm and a krypton ion laser at 568 and/or 476 nm) as compared to the incoherent light sources used in conventional microscope systems alleviates many of the optical design problems and provides the proper wavelengths needed for recognition of Papanicolaou stained cells. We also find that focus control of the scanning spot should be achievable using a technique involving a holographic grating. Other relevant considerations such as sample heating problems, multiphoton absorption by the sample, detector signal-to-noise ratios, laser amplitude noise control, and the digitization and buffering of the data stream are also discussed.

Computers↗