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Biomedical subjects

L A Jones

Publications and source records attributed to L A Jones.

At least 145 records · Page 8Linked to original sources
PubMed1989

Effects of halothane on left ventricular relaxation and early diastolic coronary blood flow in the dog.

The effects of graded concentrations of halothane on left ventricular relaxation and phasic coronary blood flow (CBF) were studied in six open-chest, anesthetized dogs. Global and regional left ventricular function were measured. Besides the expected dose-dependent depression of contractility, regional shortening, and cardiac output, halothane caused significant increases in the time constant of relaxation (Trelax), and decreased and delayed the nadir of peak negative left ventricular dP/dt. Dose-dependent reductions of CBF were noted. Percentage CBF during isovolumic relaxation was significantly reduced and showed a strong inverse correlation with Trelax. Halothane appears to interfere with the inactivation process of the heart; this in turn may impede the early rise in CBF during isovolumic relaxation.

Animals↗
PubMed1988

Characterization of an endogenous Lyt2+ T-suppressor-cell population regulating autoreactive T cells in vitro and in vivo.

Autoreactive T cells have been defined by their capacity to respond to self-Ia antigens expressed on non-T cells. Several recent studies have suggested that these cells may play important immunoregulatory functions. However, it is not clear what regulates the responsiveness of autoreactive T cells and why such cells are not demonstrably stimulated in vivo, where they are in the constant presence of self-Ia antigens. In the present study we examined the role of T suppressor (Ts) cells in regulating autoreactive T cells. We observed that enhanced autoreactivity occurred in vitro when Lyt2+ T cells were depleted from the responding and/or stimulating spleen cells in a syngeneic mixed-lymphocyte reaction. Similarly, addition of irradiated Lyt2+ T cells but not L3T4+ T cells inhibited the response of L3T4+ T cells to self-Ia antigens. The activity of the suppressor cells was specific to the autoreactive T cells since antigen-specific and alloreactive T-cell proliferation were not inhibited. Furthermore, depletion of Lyt2+ T cells by in vivo treatment of mice with anti-Lyt2 monoclonal antibodies caused enhanced endogenous proliferation of lymph node and splenic T cells and increased the T-cell response to self-Ia antigens in vitro. These studies, therefore, suggest that T-cell tolerance to self-Ia antigens in vivo may be maintained by naturally occurring Lyt2+ Ts. Mice having enhanced autoreactivity may provide a useful tool to address the role of autoreactive T cells in the immune response to foreign antigens and in the pathogenesis of autoimmune diseases.

Animals↗
PubMed1988

Isoflurane and large coronary artery haemodynamics. A study in dogs.

In the dog, stepped increases in isoflurane concentration (up to 1.5 MAC) caused peripheral and coronary vasodilatation. In the presence of significant decreases in arterial pressure (-35%), contractility (-46%), cardiac output (-17%) and coronary perfusion pressure (-40%), coronary blood flow remained unchanged, while the effective coronary vascular resistance was halved. The coronary reserve, estimated by the hyperaemic response to short periods (10 s) of coronary occlusion was reduced by the stepped increases in isoflurane concentration. Linear relationships were observed between peak hyperaemic flow, volume repayment, repayment: deficit ratio and coronary perfusion pressure. The vasodilation induced by isoflurane was of such magnitude that, at 1.5 MAC, the repayment: deficit ratio was close to unity, indicating that the vasodilatory reserve was almost exhausted.

Anesthesia, Inhalation↗
PubMed1988

Changes in the auditory middle latency responses during all-night sleep recording.

The middle latency response (MLR) using wide band-pass filters shows marked changes in amplitude, latency and configuration in sleep. The components with latencies greater than 20 ms show the greatest variability. There is a significant increase in Pa latency in stages 2 and stages 3/4, and in some cases a disappearance of the Nb component with the development of a broad positivity of latency intermediate to Pa and Pb which dominates the response. The responses in REM are of similar latency and configuration as in wakefulness but of reduced amplitude. The 40 Hz response is markedly reduced in amplitude in all sleep stages reflecting a decrease in the contribution of the middle latency components to this composite response. This appears to arise through a loss of 40 Hz periodicity in slow wave sleep and an increase in the slow 10 Hz component. In REM sleep, there is an overall reduction in amplitude. Much of the reported variability of the MLR in the literature arises from the widely differing band-pass filters used and the inadequate control for level of arousal. Both these factors have been shown to produce significant changes in the response.

Adult↗
PubMed1988

Patterns of public access to a regional poison control center: 1979 through 1986.

A routine part of the service provided by the New Mexico Poison and Drug Information Center is to perform at least 1 follow-up call on each poisoning case. Whenever practicable, public callers are asked an open-ended question during follow-up that determines where they found the poison center telephone number at the time of the original call. From 1979 through 1986, telephone number source data were collected from 101,905 public callers and categorized by 26 possible descriptors. Annual data capture rates varied from 99% (1979) to 48% (1986). These data were examined to note any changes in public access to the Center in response to the initiation and implementation of a more aggressive public outreach program in 1982 and 1983, which were considered transition years. The other years were grouped as either pre-transition (1979-81) or post-transition (1984-1986). Statistically significant (P less than 0.05) changes from the pre-transition years to the post-transition years included increased utilization of telephone labels (4.6% to 19.5%) and emergency department referrals (4.0% to 7.0%), while use of telephone directory listings and hospital operator referrals decreased (47.1% to 41.7% and 5.2% to 1.9%, respectively). In 1986, the most frequently used telephone number sources were the telephone directory (41.6%), telephone labels (23.5%), emergency department referrals (7.8%) and directory assistance (5.0%).

Health Education↗
PubMed1987

Bioavailability of estradiol as a marker for breast cancer risk assessment.

The search for a hormonal marker in breast cancer has centered on estrogens and their metabolites. However, direct measurements of total amounts of these steroids have shown no convincing or consistent differences between normal women and women with breast cancer. The purpose of this study was to measure the percentages of non-protein-bound estradiol (%NPBE) and of estradiol bound to albumin (%ABE) and the levels of sex hormone-binding globulin (SHBG) both in women with breast cancer and in those free of disease. Serum was collected and analyzed within 2 weeks, using an isodialysis method. The mean %NPBE and %ABE were significantly higher in 32 women with breast cancer (1.73 and 64.0%, respectively) than in 32 matched disease-free women (1.43 and 48.6%, respectively) (P less than 0.001). No significant difference was observed in the levels of plasma albumin when the above matched groups were compared. However, plasma levels of SHBG were significantly lower in the women with breast cancer than in either the control population or matched controls. In this finding we differ from previous studies which reported no significant differences in the mean plasma levels of SHBG. In our study, the increased %NPBE and %ABE in some patients with breast cancer may be related to a lower level of plasma SHBG; other factors, too, may affect the distribution of estradiol. Our results support the hypothesis than an increase in %NPBE and %ABE or both may indicate an increased risk of breast cancer.

Adult↗
PubMed1987

Estrogen receptors in normal salivary gland and salivary gland carcinoma.

To access for possible hormone dependence, 19 samples of normal salivary gland tissue and 14 samples of salivary gland carcinoma were quantitatively analyzed for estrogen receptor (ER) content. A receptor protein content of greater than or equal to 1 fmol/mg of cytosol protein was considered positive. Ten (77%) of 13 histologically normal samples, and four (80%) of five tumor samples obtained from male patients contained ER by this criterion, as did five (83%) of six normal samples and eight (88%) of nine tumor samples obtained from female patients. Mean ER concentrations plus or minus SE in male-derived samples were 2.02 +/- .42 fmol/mg of cytosol protein for normal tissue and 4.35 +/- 1.5 fmol/mg of cytosol protein for tumor tissue; mean ER concentrations in female-derived samples were 3.48 +/- 1.1 fmol/mg of cytosol protein for normal tissue and 12.64 +/- 6.4 fmol/mg of cytosol protein for tumor tissue. Four of eight tumors in women had levels considered to be "hormonally dependent" in breast carcinoma. These findings indicate that salivary gland carcinomas may be hormone-dependent.

Adenocarcinoma↗
PubMed1987

Quantitation of fecal carbohydrate excretion in patients with short bowel syndrome.

We performed inpatient balance studies in 11 patients to evaluate the role of carbohydrate malabsorption in the pathogenesis of the diarrhea seen in short bowel syndrome. Stool weight, total reducing substance as measured by Clinitest, and total fecal carbohydrate as measured by anthrone were determined. Patients had markedly increased fecal carbohydrate excretion, up to 65% of dietary carbohydrate intake. When the diet contained oligosaccharides, measures of total reducing substance greatly underestimated fecal carbohydrate excretion and were unreliable for quantitation. Stool weight correlated with total fecal carbohydrate excretion and with total reducing substance (r = 0.79, p less than 0.001). Multiple balance studies in 2 patients suggested a relationship between both the amount and type of dietary carbohydrate and fecal carbohydrate excretion. These studies suggest that carbohydrate malabsorption is a major cause of the watery diarrhea and subsequent fluid, electrolyte, and acid-base imbalance seen in patients with short bowel syndrome.

Child↗
PubMed1987

Differences in ischaemic dysfunction after gradual and abrupt coronary occlusion: effects on isovolumic relaxation.

The effects of both gradual and abrupt coronary occlusion on regional wall function (sonomicrometry) and left ventricular relaxation were studied in the intact dog heart. The ischaemic dysfunction observed in the two interventions as assessed by pressure-length loops showed considerably different patterns. The regional ischaemia after abrupt occlusion of the left anterior descending coronary artery was characterised by a bulge during isovolumic relaxation in contrast to the pattern observed during gradual occlusion, which was characterised chiefly by early systolic lengthening and post-systolic shortening. The effect of regional dysfunction on left ventricular relaxation was evaluated using peak negative dP/dt and tau, the time constant of isovolumic pressure decline. Abrupt occlusion had a more profound effect on relaxation than did gradual occlusion, though there were no significant changes in either pressure or flow derived indices of systolic ventricular function with abrupt occlusion of the left anterior descending artery. Two distinct patterns of regional dysfunction were produced at zero coronary flow depending on the time course of the occlusion. The regional dysfunction observed during abrupt occlusion may in part be explained by the mechanical effect of abrupt cessation of coronary flow, which in turn influences relaxation. With gradual occlusion tau was less affected even though substantial regional dysfunction was observed. This may reflect the development of collateral flow. Thus the patterns of regional dysfunction and ventricular relaxation depend on the time course of ischaemia.

Animals↗
PubMed1987

The association isoflurane-verapamil causes regional left-ventricular dyssynchrony in the dog.

In ten dogs anesthetized with 1% inspired isoflurane, the effect of low-dose verapamil on global and regional myocardial function was studied. The administration of verapamil resulted in no change in heart rate or blood pressure, but left ventricular stroke work, peak power, LV dP/dt max, and aortic blood acceleration were significantly reduced, while coronary blood flow remained unchanged. End-diastolic length increased in territory supplied by both left anterior descending (LAD) and left circumflex (LC) artery, but a significant decrease in systolic shortening occurred in the LAD segment only. Dyssynchrony of wall motion, characterized by post-systolic shortening, accompanied in three animals by a small amount of systolic lengthening, appeared with the administration of verapamil and was more pronounced in the LAD segment. Such patterns of wall motion have usually been attributed to myocardial ischemia. In the absence of significant reduction in coronary blood flow, and in the presence of a delay in onset of shortening and lengthening, these patterns of wall motion are more likely to reflect dyssynchrony of regional function than ischemia.

Anesthesia, Inhalation↗
PubMed1987

Household treatment for "chile burns" of the hands.

In New Mexico, chile peppers (Capsicum annum) are prepared by roasting and manually removing the skin from the fruit. Peeling is often done barehanded and may cause prolonged burning pain, irritation, and erythema but not vesication. In a survey of elderly Hispanic women, treatment with oils or cool tap water were frequently used home remedies. Twenty female subjects immersed their hands in a standardized slurry of green chile for 40 minutes, afterwards one hand was placed in cool tap water and the other in vegetable oil for a total of 75 minutes. Pain was scored using a visual analog scale while the hands were immersed in the chile slurry, test baths, and after drying. The difference in pain score was calculated for each subject. Analysis was by pooled regression. Cool tap water immersion initially provided more relief while vegetable oil provided better long-term relief from the pain of "chile burns".

Adult↗