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Biomedical subjects

C Shaw

Publications and source records attributed to C Shaw.

At least 343 records · Page 19Linked to original sources
PubMed1986

The laminar distributions and postnatal development of neurotransmitter and neuromodulator receptors in cat visual cortex.

We review efforts to further understand the development and nature of sensory processing mechanisms in the cat visual cortex. In vitro autoradiographic and homogenate assay techniques have been employed to determine the laminar distribution and characteristics of various neurotransmitter and neuromodulator receptor populations during postnatal development. Each receptor population shows a distinct laminar-specific pattern of binding, which, in most cases, is age-dependent. Changes in receptor number and affinity are also observed during postnatal development. These findings indicate that major alterations in the basic chemical circuitry of cat visual cortex are a normal feature of postnatal maturation and may play a role in plasticity mechanisms.

Aging↗
PubMed1986

Medical imaging in asthma.

Asthma is a common disease characterized by hyperreactivity of airways to a variety of stimuli. Efficacy studies have shown that while in adults there is no positive predictive value between radiographic abnormalities and certain clinical parameters, in children there may be some correlation with age and the presence of rales. In the Yale-New Haven Emergency Service it is suggested that certain clinical criteria be used to determine which patients receive chest radiographs. A retrospective review of 563 adult asthmatics who presented to the Yale Emergency Room revealed that one third of the patients were radiographed; 50% of these were over 50 years of age, and the overall incidence of radiographic abnormalities that would change patient management was only 3%. Radiographic findings have been categorized into two groups, uncomplicated and complicated asthma, depending on whether bronchodilators will effect a response.

Adult↗
PubMed1986

Effects of micellar oleic acid on canine jejunal blood flow and neurotensin release.

The purpose of this study was to evaluate the role of neurotensin in the local regulation of the lipid-induced jejunal hyperemia. Total blood flow and the arteriovenous hormone concentration difference were measured in isolated jejunal loops of anesthetized dogs with either saline, bile (10% in normal saline), oleic acid (40 mM in normal saline), or oleic acid and bile in the lumen. The bile-oleic acid mixture produced a sustained increase (+25 +/- 3%) in jejunal blood flow, whereas neurotensin release reached a maximum (1.14 +/- 0.34 pmol X min-1 X 100 g-1) 2 min after initiation of the response and then returned to control. Venous neurotensin concentrations also reached a maximum (51 +/- 17 pmol/l) at 2 min. There were no significant changes in either blood flow or neurotensin release in response to the other test solutions. Intra-arterial infusion of neurotensin did not significantly decrease jejunal vascular resistance (-12 +/- 3%) until venous concentrations of 478 +/- 101 pmol/l were attained. It seems unlikely, then, that neurotensin plays any role in the regulation of the lipid-induced jejunal hyperemia.

Animals↗
PubMed1986

Gastric emptying of a solid-liquid meal and gastro-intestinal hormone responses in patients with erosive oesophagitis.

Abnormal gastric motility has been recognised recently in some patients with excessive gastro-oesophageal reflux. The cause of this motility disturbance is unknown. A dual isotope study has been used to assess gastric emptying of solid and liquid components of a test meal in 16 patients with erosive oesophagitis and in 16 control subjects. The release of insulin, gastrin, pancreatic polypeptide, gastric inhibitory polypeptide and neurotensin in response to the test meal was monitored in all subjects. A significant delay in both solid and liquid emptying was observed in patients with erosive oesophagitis. However, they demonstrated no alteration in the pattern of hormone release in response to the test meal.

Adult↗
PubMed1986

Meal-stimulated neurotensin immunoreactivity in plasma following gastric surgery: characterisation with two region-specific antisera.

Plasma neurotensin (NT) response to a simple fatty meal, administered via an indwelling naso-gastric tube, has been assessed in two groups of subjects following gastric surgery without resection, and in healthy controls. Two region-specific NT antisera were employed in the radioimmunoassay (RIA) of plasma samples. The first, NT3, recognises only NT 1-13 in plasma extracts, while the second, GNT 21, recognises NT 1-13, NT 1-11 and NT 1-8 equally. In addition, plasma extracts were subjected to reverse-phase high performance liquid chromatography, fractions from which were subjected to each region-specific RIA. There was no significant response to the test meal in the healthy controls. However, both groups of post-gastric surgery subjects, who had undergone either vagotomy and pyloroplasty (V & P) or vagotomy and gastrojejunostomy (V & GJ), displayed significant increases in both intact and N-terminal plasma NT immunoreactivity (IR). The integrated responses of the V & P and V & GJ groups were also significantly higher than the control response but did not differ significantly from one another. The proportion of intact NT to total N-terminal NT-IR in each group was not significantly different.

Adult↗
PubMed1986

Circulating gastrointestinal hormones in patients with flatulent dyspepsia, with and without gallbladder disease.

Fasting and post-prandial circulating levels of insulin, gastrin, gastric inhibitory polypeptide, pancreatic polypeptide and neurotensin were measured in patients with flatulent dyspepsia, with and without gallbladder disease and post-cholecystectomy. Levels were also measured in non-dyspeptic patients with gallbladder disease and normal controls. There were no consistent significant differences from controls for fasting and post-prandial responses in patients with a history of dyspepsia or those who experienced dyspepsia at the time of the test. In patients with gallbladder disease, with and without dyspepsia, there was a reduced neurotensin response compared to normal controls. It is concluded that circulating levels of these hormones are not related to symptoms of flatulent dyspepsia.

Dyspepsia↗
PubMed1986

Enlarging, atypically located pericardial cyst. Recent experience and literature review.

Pericardial cysts frequently are recognized when they present in a cardiophrenic angle, but may not be suspected when they occur elsewhere in the chest. To highlight the unusual presentations of pericardial cysts, we present two patients with cysts in the upper mediastinum and review the reported experience with similar lesions. Our patients' cysts are particularly instructive because one cyst enlarged over 23 months and because the other did not appear cystic on a computerized tomographic scan. Because percutaneous aspiration may be an attractive alternative to surgical resection when a pericardial cyst is suspected, clinicians should include pericardial cyst in the differential diagnosis of upper mediastinal masses.

Adult↗
PubMed1986

Lung cancer in the elderly.

Lung cancer is the most common malignancy in the elderly population and was responsible for greater than 125,000 deaths in 1985. Although advances have been made in the areas of diagnosis and staging, the long-term outlook for the disease remains poor, primarily because of dissemination of disease prior to diagnosis. Despite this, several studies suggest that lung cancer in the elderly is a more indolent disease process, which should be treated in the same manner as it is in the young population.

Adult↗
PubMed1986

Characterization, distribution, and ontogenesis of adenosine binding sites in cat visual cortex.

In vitro autoradiographic techniques were used to characterize binding sites for 3H-cyclohexyladenosine (CHA) and 3H-5'-N-ethylcarboxamidoadenosine (NECA) in cat and kitten visual cortex. 3H-CHA binding sites in adult cat have a Bmax of 1,363 fmol/mg protein and a Kd of 6.8 nM. Displacement experiments indicate that 3H-CHA binds to an adenosine receptor similar to the A1-adenosine receptor described by other investigators. 3H-NECA binding sites in adult cat have a Bmax of 518 fmol/mg protein and a Kd of 15.4 nM. Displacement experiments do not allow us to identify this binding site unambiguously. Bmax values increase during postnatal development for both binding sites, peaking in adulthood for 3H-CHA and at 30 d for 3H-NECA. Kd values show neither consistent nor significant differences during postnatal development for either binding site. 3H-CHA and 3H-NECA binding sites are concentrated in layers 1-3 and upper layer 5 in the visual cortex of adult cats. These laminar patterns, however, change during postnatal development, showing the densest binding in the deep cortical layers (5 and 6) in kittens younger than 30 d of age and a fairly homogeneous binding in older kittens before achieving the adult distribution.

Animals↗
PubMed1985

Detection and quantitation of low levels of protected and unprotected (R)-amino acids in the synthesis of thymopentin, an immunoregulatory peptide.

Two chiral chromatographic procedures (HPLC and capillary GC) were developed to monitor the extent of epimerization of protected and unprotected amino acids used in a synthesis of thymopentin, an immunoregulatory peptide currently in clinical trials. The capillary GC method allowed the detection of the (R)-enantiomer in the presence of the (S)-enantiomer at levels of greater than or equal to 0.2%, while the HPLC method allowed similar detection at levels of greater than or equal to 0.1%.

Amino Acids↗
PubMed1985

Vincristine-induced abnormalities of gastrointestinal regulatory peptide cells of the rat. An immunocytochemical study.

The microtubule-disrupting drug vincristine is a common component of anti-cancer chemotherapeutic regimes, which produces acute constipation as a side effect. Although generally attributed to damage to the myenteric plexus, the precise mechanism of this disturbance is unknown. In addition, vincristine causes marked aberrations in the secretory response of pancreatic endocrine tissue in both man and rats. No information is available on its possible effect on regulatory peptides of the gastrointestinal tract. In this study we have produced vincristine-induced constipation in rats at a dosage comparable with that employed in the treatment of human subjects. Immunocytochemistry revealed concomitant disturbances in cells exhibiting immunoreactivity for gastrin in the antrum, for gastric inhibitory polypeptide and 5-hydroxytryptamine in the duodenum, for enteroglucagon in the colon, and for somatostatin in all three sites. These widespread effects are transient in nature with normal cell numbers and morphology being reestablished within 6 days. It is suggested that the observed effects are a direct result of microtubule disruption and that gastrointestinal regulatory peptide and amine immunoreactive cells have a rapid regeneration potential.

Animals↗
PubMed1985

Influence of a transplantable insulinoma on the pancreatic status of insulin and pancreatic polypeptide in the rat.

The effect of endogenous hyperinsulinaemia, produced by syngeneic transplantation of rat insulinoma at an extrapancreatic site, on pancreatic insulin and pancreatic polypeptide has been examined by radioimmunoassay and immunohistochemistry. Twenty days after subcutaneous transplantation, tumour-bearing rats exhibited marked hyperinsulinaemia and hypoglycaemia, with plasma pancreatic polypeptide concentrations similar to controls. Immunoreactive insulin levels in the head and tail of pancreas of tumour-bearing rats were reduced by 90-95% compared with control animals. Immunoreactive pancreatic polypeptide levels in the head of the pancreas were reduced by 70%, but the relatively low levels of peptide in the pancreatic tail were similar in tumour-bearing and control rats. Insulin and pancreatic polypeptide cells were weakly immunofluorescent in tumour-bearing rat pancreas. In conclusion, the presence of an insulinoma at an extrapancreatic site resulted in a severe depletion of endogenous insulin and pancreatic polypeptide, suggesting that there is a functional relationship between the beta and pancreatic polypeptide cell.

Adenoma, Islet Cell↗
PubMed1985

Modification of neurotransmitter receptor sensitivity in cat visual cortex during the critical period.

We have examined the characteristics of various receptors in cat visual cortex during postnatal development. These included beta-adrenergic, GABA, benzodiazepine and acetylcholine receptors. For each population of receptor the number (Bmax) and affinity (Kd) were examined as a function of postnatal age (3 days-adult). For all receptors examined, the Bmax increased during development from low early values to a peak within the critical period. The Kd also changed during development for most receptors. The simultaneous alterations in Bmax and Kd necessitate defining a term which takes both of these receptor properties into consideration. This term, called receptor sensitivity (RS), provides a more comprehensive measure of receptor function than either Bmax or Kd alone. Using this measure, we find that receptor sensitivity is low near birth for the 4 receptor populations studied, rises to a peak within the first two months of life, and then declines to near-neonatal levels for 3 of the 4 receptor populations.

Animals↗
PubMed1985

Alterations in the laminar distribution of pentagastrin binding sites in cat visual cortex during postnatal development.

The distribution and characteristics of [3H]pentagastrin (CCK-5) binding sites were examined in the visual cortex of cats of varied age. CCK-5-labelled binding sites in a highly age-dependent, laminar-specific manner. In young kittens, CCK-5 binding sites were found dominantly in layers IV-VI. During the first 3 months of postnatal development the laminar pattern of binding changed so that by 95 days postnatal, layers I-III and VI were the most densely labelled. CCK-5 binding sites appear to be members of a class of receptors which exhibit laminar alterations in their distribution during early postnatal development.

Age Factors↗
PubMed1985

Effect of acarbose on biochemical responses and clinical symptoms in dumping syndrome.

A dose of 50 mg of acarbose was administered with a standard breakfast to 13 subjects with dumping syndrome. Significant attenuation of hyperglycaemia (p less than 0.01) was observed, and rises in plasma gastric inhibitory polypeptide, insulin and enteroglycagon were reduced (p less than 0.05). Plasma levels of neurotensin, vasoactive intestinal polypeptide and somatostatin were not affected. Dumping score was reduced, but this did not achieve statistical significance. In a longer-term study, 9 patients took acarbose, 50 mg t.i.d., for 1 month. No significant reduction in the number or severity of dumping attacks was observed, but a majority expressed a preference for the drug and some individuals experienced a marked improvement of symptoms.

Acarbose↗