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Biomedical subjects

M Walsh

Publications and source records attributed to M Walsh.

At least 289 records · Page 16Linked to original sources
PubMed1984

The enlarged carotid body of the chronically hypoxic and chronically hypoxic and hypercapnic rat: a morphometric analysis.

Rats were subjected to chronic hypoxia (10% O2) or hypoxia and hypercapnia (10% O2 + 4% CO2) for 3-4 weeks and their carotid bodies (twenty-three from twenty rats) were compared with those of litter-mate controls. Both chronic exposures, which simulated high altitude or chronic lung disease, caused a 4-10-fold increase in carotid body volume. The larger increases were attributed to higher fixation-perfusion pressures. The organs were fixed by perfusion with glutaraldehyde. Semi-thin (1 micron) sections for light microscopy and ultra-thin sections for electron microscopy were cut at regular intervals and were examined by stereological techniques to determine the nature of the enlargement. The proportion occupied by blood vessels was much increased in both chronic hypoxia and hypoxia plus hypercapnia; the endothelium appeared stretched with conspicuous fenestrations. There were increased numbers of endothelial cells which suggested new growth as well as stretching of endothelium and the mean transectional area of the vessels was increased. The mean surface area of blood vessels per unit area of carotid body was unaltered but the total surface area of blood vessels in the whole carotid body was greatly increased. Both the Type 1 cell nucleus and cytoplasm were increased in size. The proportion nucleus/cytoplasm was unaltered in hypoxia but reduced in hypoxia plus hypercapnia. There were fewer Type 1 cell nuclei per unit area but the estimated total number of Type 1 cell nuclei per carotid body was increased 2-4-fold; this was interpreted as Type 1 cell hyperplasia. Some of the dense-cored vesicles in Type 1 cells were enlarged with eccentric dense cores but their number per unit area of cytoplasm was decreased. Their mean size was not significantly altered. However, the total number of vesicles per carotid body was presumed to be increased because their decreased density in the cell was offset by a greater increase in total Type 1 cell volume. The harmonic and arithmetic mean distances between endothelium and the boundary of glomus tissue were significantly reduced. The harmonic mean distance is an indication of the diffusion distance for gases to and from blood and glomus tissue. The arithmetic mean distance is a measure of the amount of tissue in between. The significance of the vascular enlargement and hyperplasia and the Type 1 cell hyperplasia cannot be assessed at present. We do not know if enlargement is associated with the same, greater, or lesser activity of the organ for a given stimulus.

Animals↗
PubMed1984

Osteoid osteoma: excision with scintimetric guidance.

The definite diagnosis of osteoid osteoma relies on the demonstration of the nidus, best shown by CT, which also provides precise preoperative localization of the nidus. While bone-block excision to remove the nidus is feasible in the long bones, there may be unacceptable sequelae in the vertebral column and small bones of the hands. By precisely localizing the nidus, radionuclide scintimetry permits excellent therapeutic results, with minimal morbidity.

Adolescent↗
PubMed1984

Evaluation of Blom-Singer voice prosthesis.

Tracheoesophageal puncture and use of a silicone prosthesis is becoming a common and highly effective procedure for voice rehabilitation in the alaryngeal patient. Radiologic evaluations were reviewed of 31 patients scheduled for tracheoesophageal puncture at this institution over the past 3 years. Barium swallow examinations were performed preoperatively to assess anatomy and muscular activity of the pharyngoesophagus. Examinations were performed postoperatively when complications were suspected, phonation was unsatisfactory, or as routine oncologic follow-up. Postoperative complications included neck abscess, cervical osteomyelitis, and feeding tube dissection into the anterior wall of the thoracic esophagus. This method of pre- and postoperative radiologic evaluation of these patients is presented, along with the radiologic manifestations of the complications.

Aged↗
PubMed1983

Fluorophotometric evaluation of capillary permeability in gram-negative shock.

We developed a new method by which capillary permeability changes secondary to gram-negative sepsis can be easily monitored. In a preliminary trial, ten dogs were injected intravenously with live Escherichia coli. Progressive extravasation of fluorescein from the retinal capillary bed was demonstrated by retinal angiography, thus indicating "capillary leak." In a subsequent trial, fluorophotometry facilitated direct quantitation of this leak. Three control and three septic dogs underwent continuous hemodynamic and physiologic monitoring. Hourly retinal fluorophotometric measurements were recorded. The control group demonstrated no capillary leak nor any change in hemodynamic and physiologic status. In the septic group, there was a dramatic increase in extravascular fluorescein concentration two to four hours after E coli infusion, correlating well with hemodynamic and physiologic parameters typical of gram-negative shock.

Animals↗
PubMed1983

Production and preliminary characterization of monoclonal antibodies directed at two surface proteins of rhesus rotavirus.

A series of monoclonal antibodies was isolated which reacted with one of two major surface proteins of rhesus rotavirus. Thirty-six monoclonal antibodies immunoprecipitated the 82-kilodalton outer capsid protein, the product of the fourth gene, the viral hemagglutinin. These monoclonal antibodies exhibited hemagglutination inhibition activity and neutralized rhesus rotavirus to moderate or high titer. Three monoclonal antibodies immunoprecipitated the 38-kilodalton outer capsid glycoprotein, the eighth or ninth gene product. These three monoclonal antibodies neutralized rhesus rotavirus to high titer and also inhibited viral hemagglutination.

Animals↗
PubMed1983

Alveolar deposition of sized particles of 239PuO2 in the mouse.

Data on the alveolar deposition of 239PuO2 particles in the mouse are presented. It is shown that alveolar deposition falls with increasing activity median aerodynamic diameter (AMAD) over the range 0.6 to 2.4 microns. In the mouse, any peak in alveolar deposition must occur at an AMAD of less than 1 micron. Information is also provided on the relative lobar concentrations (RLCs) of 239PuO2. The RLC is greatest in the right apical lobe and increases quite sharply with AMAD. The RLCs of the other lobes of the right lung decline with AMAD. The RLC in the left lobe is relatively unaffected by AMAD.

Aerosols↗
PubMed1982

Effect of limited access to sucrose on overeating and patterns of feeding.

Four groups of adult rats, housed on a 12-12, light-dark cycle, were allowed access to a nutritionally complete diet and water. Three of these groups were also offered a 32% solution of sucrose. The sucrose was available for either the 24-hour period, the 12 hours of light or the 12 hours of dark. Access to sucrose led to overeating and excessive weight gain. These effects were more pronounced when the sucrose was available for the 24-hour period or during the dark. Limited access to sucrose produced a reversal of the rat's usual circadian pattern of feeding when the sucrose was available during the light and increased the rat's nocturnal hyperphagia when it was available during the dark. Sucrose intake and the proportion of calories taken from sucrose were higher in the 24-hour access group and the dark access group than the light access group. Access to sucrose did not induce a pattern of dietary selection that compromised growth or health. It appears that access to a palatable carbohydrate solution can lead to overeating and major changes in the circadian organization of feeding behavior. These data emphasize the potent role that external factors can play in the control of ingestive behavior.

Animals↗
PubMed1979

Analgesic treatment with levomepromazine in acute myocardial infarction. A randomized clinical trial.

The efficacy of a non-narcotic analgesic is evaluated in a double-blind randomized series of patients with acute myocardial infarction (AMI). Levomepromazine or pethidine were given in 328 consecutive cases to 316 patients within 24 hours after the onset of symptoms. Levomepromazine, 12.5 mg, appeared as effective as pethidine, 50 mg, in the alleviation of pain, though the initial dose had to be higher. Nausea and vomiting were half as frequent in the levomepromazine group as in the pethidine group (p less than 0.001). The incidences of arrhythmias, lung oedema, hypotension and thromboembolic complications did not differ between the groups. The mortality rate in the first 4 weeks was 22% in the levomepromazine group and 37% in the pethidine group (p less than 0.005), and after one year 39 and 50% (p less than 0.05), respectively. It is concluded that levomepromazine is better tolerated than pethidine in AMI. This suggests that the present management of pain in AMI should be reconsidered.

Acute Disease↗
PubMed1979

Circular dichroism studies of native and chemically modified Ca2+-dependent protein modulator.

The structural features of the native Ca2+-dependent protein modulator and two chemically modified derivatives, namely, nitrotyrosyl modulator and alkylated modulator, were examined by circular dichroism. The binding of Ca2+ to the native molecule was accompanied by an increase in helical content from 40 to 49%, with little effect on the local environments of aromatic residues in the modulator. The Mg2+ and Mn2+ do not elicit the conformational change induced by the binding of Ca2+, which also stabilizes the modulator against urea denaturation. The overall secondary structure of nitrotyrosyl modulator is indistinguishable from that of the native protein and undergoes a similar conformational change upon binding Ca2+. These observations are in agreement with the fact that nitration has no effect on modulator functions. Furthermore, nitrotyrosyl modulator interacts with troponin I only in the presence of Ca2+, as detected by circular dichroism (cd). On the other hand, alkylation of five methionine residues on the modulator with benzyl bromide affects protein conformation, as evidenced by a reduced helical content of only 35%. Alkylated modulator retains the ability of the native protein to bind Ca2+ although the affinity of this derivative for Ca2+ is reduced some three orders of magnitude relative to the native protein, with Kd = 3.2 X 10(-4) M. The results with the alkylated modulator, in conjunction with previous cd studies on N-chlorosuccinimide oxidized modulator are utilized to advance a model for the Ca2+ activation of modulator protein, based on three conformational states of the molecule.

Alkylation↗