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Biomedical subjects

L Nash

Publications and source records attributed to L Nash.

18 recordsLinked to original sources
PubMed2001

Functional categories and syntactic operations in (Ab)normal language acquisition.

This article argues in favor of the hypothesis that computational complexity determines order of acquisition of functional categories by normal children and patterns of impairment vs. relative preservation of these categories in children with Specific Language Impairment. Complexity is defined in terms of the properties of functional categories of the language the (ab)normal child is acquiring. The results of a study on present/past tense production and comprehension, carried out with children with and without Specific Language Impairment confirm the predictions of the computational complexity hypothesis. It is shown that it is easier to compute kernel functional categories than those that introduce further semantic modifications in the sentence.

Adolescent↗
PubMed1998

In vitro formation by reverse dialysis of collagen gels containing highly oriented arrays of fibrils.

Acid extracts of rat tail tendon were subjected to reverse dialysis against 0.5% PEG at 4 degrees C in an attempt to induce liquid crystallization. After 48 h, gel and fibril formation were initiated by continuing dialysis at 20 degrees C against the same PEG solution adjusted to pH 7.4. The inclusion of calcium- or magnesium chloride (final concentration 0.3-33 mM) in the collagen solution before dialysis resulted in strongly birefringent gels that showed a progressive rotation of the slow axis of birefringence with increasing distance from the lateral margin of the gel. The gels contained fibers running predominantly in the plane of the flattened gel and crossing at angles of between 55 degrees and 90 degrees. We suggest that liquid crystallization is responsible for this phenomenon and that it might be possible to exploit this to produce materials for tissue engineering.

Animals↗
PubMed1996

The delusion of infection with HIV.

OBJECTIVE: This article briefly describes the consultation-liaison service of the HIV/AIDS service of the Royal North Shore Hospital, and reviews three men who had the delusional belief of being infected with HIV. METHOD: Twenty-three consecutive referrals from the HIV/AIDS unit to consultation-liaison psychiatry were reviewed. Three of these patients persistently believed that they were infected with HIV despite low risk factors and negative blood tests. RESULTS: These three men had a major depression. Two of the three patients were offered treatment with psychotherapy and antidepressant medication. The third declined psychiatric follow-up. CONCLUSION: The presentation of a patient for HIV testing, with an atypical history, should raise the interviewer's concern that there may be an underlying mental illness, in particular a depressive disorder.

AIDS Serodiagnosis↗
PubMed1990

Models of helping and coping, responsibility attributions, and well-being in community elderly and their helpers.

The analysis of Brickman et al. (1982), which separates attribution of a problem's cause and solution, was tested in 4 studies. Young and elderly adults' (n = 210) well-being was related only to taking responsibility for solutions. The elderly compared with the young adults assumed less responsibility for problem cause and solution. They also preferred helping and coping models that assume low self-responsibility for solutions (e.g., medical model). This result was replicated with Meals on Wheels clients (n = 51). An intragenerational helping pattern was found in Study 3. Lay helpers (n = 63) helped mainly same-age recipients. Elderly and middle-aged helpers compared with young adults preferred using a medical model. Overall, a cohort bias in model preference was suggested. In Study 4, problem type and recipient age moderated attributions and model choice of young and middle-aged Ss (n = 92). Relevance to the control literature and ethical and clinical implications of a medical-model bias are discussed.

Adaptation, Psychological↗
PubMed1988

Secretion of bicarbonate by rat distal tubules in vivo. Modulation by overnight fasting.

We have performed microperfusion studies on distal tubule bicarbonate reabsorption (JtCO2) of fed and fasted rats to extend our previous observations of in vivo bicarbonate secretion and to resolve certain discrepancies between free-flow and microperfusion data. When rats are fasted overnight, as in previous free-flow studies, distal tubule microperfusion with a 28-mM tCO2 solution results in significant JtCO2 (53 +/- 6 pmol.min-1.mm-1) at normal flow and increases briskly (91 +/- 16 pmol.min-1.mm-1) with bicarbonate load. This response is not influenced by the addition of other normal tubular fluid constituents. However, when normally fed rats are used, as in our previous microperfusion studies, distal tubule JtCO2 is not different from zero when a 28-mM tCO2 solution is perfused at normal flow rates but becomes negative (-54 +/- 13 pmol.min-1.mm-1) at high flow rates, which indicates the existence of bicarbonate secretion against a concentration gradient. Alkali loading of fasted rats also elicits bicarbonate secretion at high flow. These results demonstrate for the first time that normal feeding or alkali loading can induce bicarbonate secretion in a mammalian nephron segment in vivo, and resolves previous discrepancies between free-flow and microperfusion data.

Absorption↗
PubMed1986

Distal tubule bicarbonate accumulation in vivo. Effect of flow and transtubular bicarbonate gradients.

We have performed microperfusion studies on distal tubules of normal and alkalotic rats in an attempt to demonstrate in vivo bicarbonate secretion. All perfusion solutions were free of phosphate and other nonbicarbonate buffers. In both normal and alkalotic rats, distal perfusions elicited significant tCO2 entry only at high flow (24 nl/min). Even when perfusate tCO2 concentration closely matched plasma tCO2 concentration (30 mM tCO2), significant tCO2 entry again occurred at high flow. This was associated with a rise of the perfusate tCO2 concentration, which indicated net entry of tCO2 against a concentration gradient. In this "symmetrical" perfusion situation, acetazolamide blockade prevented tCO2 entry. Accordingly: distal tubule tCO2 entry is demonstrable in both alkalotic and normal rats at high flow rates; increasing perfusate tCO2 concentration can suppress tCO2 entry; and entry can occur in the absence of a gradient and this effect can be blocked by acetazolamide.

Acetazolamide↗
PubMedDate not supplied

The influence of potassium depletion on cardiac growth response to pressure overload.

Previous studies have reported that potassium depletion arrests both body and heart growth, and that aortic ligation can induce myocardial potassium loss. To examine the effects of potassium depletion on the cardiac growth response to an increase in pressure load, we induced severe potassium depletion in rats by dietary means for 3 weeks and then subjected them to aortic ligation. 3 weeks following ligation and after a total of 6 weeks of continued potassium deprivation, the animals were sacrificed. Our results show that after aortic ligation the left ventricular weight in potassium depleted rats significantly increased by an average of 155 mg, a value which was somewhat less than the 208-mg increase observed in normokalemic animals. The presence of focal myocardial necrosis in hypokalemic rats, accordingly, did not appear to prevent the increase in ventricular mass induced by augmented pressure load. Furthermore, despite marked reduction in skeletal muscle potassium content there was no decrease in the myocardial potassium content even after aortic ligation. We conclude that profound dietary potassium depletion for a prolonged period of 6 weeks does not impede the cardiac growth response to an increase in pressure load.

Animals↗
PubMedDate not supplied

Effect of sex bias on women's studies on alcoholism.

Women alcoholics have historically been underrepresented in research studies far out of proportion to the difference in male female prevalence rates. This study examined disparities in the ways in which male and female alcoholics have been studied in the treatment outcome literature and examined the role of sex bias (author sex) as a contributing factor. Two hundred fifty-nine studies published between 1972 and 1980 were reviewed that reported drinking-related outcome of subjects treated with psychological intervention or medication. Only 7.8% of subjects sampled in these studies were women. Of greater interest, female authors sampled nearly 3 times as many women in proportion to the number of people they studied as did male authors; women subjects were more than one and one-half times as likely to be followed up by female than by male authors; and 3 times as many female as male authors presented data examining sex differences. The same kind of differences between male and female authors occurred with respect to specifying precise numbers of male and female subjects studied and followed up, and with respect to examining prognostic variables related to women's outcome. The data suggest that subtle sex bias contributes to inadequate studying of women alcoholics.

Alcoholism↗