Effects of effort and social modeling on drinking in humans

The role of economic and social influences on water intake in humans was explored in two experiments. In the first experiment, the effect of water cost (as defined as the amount of effort required to acquire water) on prandial drinking was studied by manipulating water position during an ad libitum meal: water was available either on the dining table, about 20 feet from the table, or approximately 40 feet away. Subjects drank significantly more when the water was on the table than in the other conditions; but a linear relationship between cost (distance) and intake was not observed. In the second experiment, the effects of water cost and a social model on drinking were assessed in a similar paradigm. Increasing effort required to obtain water significantly reduced prandial water intake, and the presence of a social model increased water intake. Although some interesting trends emerged, no significant interactions between social and economic factors were found. These experiments demonstrate that environmental factors can significantly affect facultative drinking in humans.

Prognostic implications of baseline electrocardiographic features and their serial changes in subjects with left ventricular hypertrophy

BACKGROUND

During the past half-century, the ECG has been used extensively for the diagnosis of left ventricular hypertrophy. Persons with ECG evidence of left ventricular hypertrophy are at increased risk for the development of cardiovascular disease.

METHODS AND RESULTS

Subjects from the Framingham Heart Study with ECG evidence of left ventricular hypertrophy were eligible for this investigation if they were free of cardiovascular disease and did not have complete bundle-branch block or Wolff-Parkinson-White syndrome. Logistic regression analyses of pooled biennial examinations were used to determine risk for cardiovascular disease as a function of baseline voltage (sum of R wave in aVL plus S wave in V3) and repolarization and as a function of serial changes in these ECG features of hypertrophy. The eligible sample consisted of 274 men (mean age, 60 years) and 250 women (mean age, 64 years) who contributed 2660 person-examinations. During follow-up, there were 269 new cardiovascular events. Compared with subjects in the first quartile of voltage at baseline, the age-adjusted odds ratio for cardiovascular disease among subjects in the fourth quartile was 3.08 (95% confidence interval [CI], 1.87 to 5.07) in men and 3.29 (95% CI, 1.78 to 6.09) in women. Compared with a normal repolarization pattern, the presence of severe repolarization abnormalities was associated with an age-adjusted odds ratio of 5.84 (95% CI, 3.55 to 9.62) in men and 2.47 (95% CI, 1.38 to 4.42) in women. Subjects with a serial decline in voltage were at lower risk for cardiovascular disease than were those with no serial change (men: odds ratio after adjusting for age and baseline voltage, 0.46; 95% CI, 0.26 to 0.84; women: odds ratio, 0.56; 95% CI, 0.30 to 1.04). In contrast, those with a serial increase in voltage were at greater risk for cardiovascular disease (men: odds ratio, 1.86; 95% CI, 1.14 to 3.03; women: odds ratio, 1.61; 95% CI, 0.91 to 2.84). Compared with those with no serial change, an improvement in repolarization was associated with a marginally significant reduction in cardiovascular risk in men (odds ratio after adjusting for age and baseline repolarization, 0.45; 95% CI, 0.20 to 1.01). Worsening of repolarization was associated with increased risk for cardiovascular disease in both sexes (men: odds ratio, 1.89; 95% CI, 1.05 to 3.40; women: odds ratio, 2.02; 95% CI, 1.07 to 3.81).

CONCLUSIONS

The results of this investigation suggest that regression of ECG features of left ventricular hypertrophy confers an improvement in risk for cardiovascular disease, whereas serial worsening imposes increased risk. The benefits to be derived from regression of left ventricular hypertrophy must be confirmed in other clinical settings.

Prediction of alpha-helices in proteins with the hydrophobic strip-of-helix template and distributions of other amino acids around the hydrophobic strip

Upon addition of requirements for highly characteristic distributions of helix-stabilizing residues to an alpha-helix predictor based upon identification of a longitudinal, hydrophobic strip-of-helix pattern, maximal sensitivity and efficiency scores approached 50% levels at a high degree of stringency. The hydrophobic strip-of-helix template ([symbol: see text], joined in a circle) was applied to 247 helices to maximize the strip-of-helix hydrophobicity index (SOHHI; the mean hydrophobicity of residues in [symbol: see text] positions). Statistically significant increases or decreases in the frequencies of certain residues are observed in some [symbol: see text] and [symbol: see text] positions: [symbol: see text] in the helix (including N- and C-terminal [symbol: see text] in the helix): Leu, Ile, Val, Phe, and Met; first [symbol: see text] positions in extensions of the template to surrounding segments: not increased Leu, Ile, Val, Phe, or Met; N-terminal [symbol: see text]: Asp, Glu; C-terminal [symbol: see text] and the first [symbol: see text] after the helix: His, Lys, Arg; N-terminal [symbol: see text]: Asn; C-terminal [symbol: see text]: Gln; smallest residue in longitudinal strip-of-helix: Ala or Val at crossing points between helices. An algorithm was then derived to indicate alpha-helices by merging predictions with templates [symbol: see text] and [symbol: see text], where the SOHHI > or = 3.0 in the Kyte-Doolittle scale. Relative to the baseline prediction using only the template, more elaborate rules using combinations of other structural patterns produced more efficient (49 versus 42%, respectively) but less sensitive (32 versus 42%, respectively) predictions when the prediction was required to overlap substantially with the known helix. These maximal sensitivities and efficiencies imply that some helices may be formed in folding intermediates but are lost upon coalescence of the final form. Better predictions of protein structure from the primary sequence may require modeling of competing interactions of local structures in folding intermediates.

Comparison of actual and random-positioning-model distributions of peptide scavenging and T cell-presented sites in antigenic proteins

In a peptide with a T cell-presented epitope (T site), a folded structure with a hydrophobic surface, 'the scavenger (S) site', may regulate transfer to major histocompatibility complex class II molecules. Three procedures which were proposed to identify T sites selected for amphipathic helical patterns but not T sites. In testing whether S sites lay in or near T sites, we found their linkage was not greater than that generated by a model in which segments of equal length and number to the S and T sites for each protein were distributed at random. This study establishes criteria for evaluation of schemes to predict functional motifs in antigenic proteins.

FMH-induced decrease in central histamine levels produces increased feeding and body weight in rats

The present study tested the long-term effects of the histamine (H) synthesis inhibitor alpha-fluoromethylhistidine (FMH) on feeding and body weight in rats. FMH (administered via 2-week osmotic minipumps) increased feeding significantly throughout the test period. Body weights were also significantly increased toward the end of the test period. Hypothalamic H assays, performed at the end of the study, confirmed that FMH-treated rats had significantly lower H levels than controls. In general, the results suggest that H activity and feeding are inversely related.

Sequence analysis and protein import studies of an outer chloroplast envelope polypeptide

A chloroplast outer envelope membrane protein was cloned and sequenced and from the sequence it was possible to deduce a polypeptide of 6.7 kDa. It has only one membrane-spanning region; the C terminus extends into the cytosol, whereas the N terminus is exposed to the space between the two envelope membranes. The protein was synthesized in an in vitro transcription-translation system to study its routing into isolated chloroplasts. The import studies revealed that the 6.7-kDa protein followed a different and heretofore undescribed translocation pathway in the respect that (i) it does not have a cleavable transit sequence, (ii) it does not require ATP hydrolysis for import, and (iii) protease-sensitive components that are responsible for recognition of precursor proteins destined for the inside of the chloroplasts are not involved in routing the 6.7-kDa polypeptide to the outer chloroplast envelope.

Differential effects of psychotropic drugs on feeding in rats: is histamine blockade involved?

The present animal studies tested the hypothesis that drug-induced blockade of histamine-1 receptors leads to appetite stimulation. Test agents included the antipsychotic promazine which has very potent antihistaminic effects, as well as the antipsychotic haloperidol and the antidepressant desipramine which both have negligible antihistaminic effects. In support of the hypothesis, significant appetite stimulation occurred only with promazine, while the other two test agents did not increase feeding, and even produced some suppression in food intake.

Cloning and sequence analysis of cDNAs encoding the cytosolic precursors of subunits GapA and GapB of chloroplast glyceraldehyde-3-phosphate dehydrogenase from pea and spinach

Chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is composed of two different subunits, GapA and GapB. cDNA clones containing the entire coding sequences of the cytosolic precursors for GapA from pea and for GapB from pea and spinach have been identified, sequenced and the derived amino acid sequences have been compared to the corresponding sequences from tobacco, maize and mustard. These comparisons show that GapB differs from GapA in about 20% of its amino acid residues and by the presence of a flexible and negatively charged C-terminal extension, possibly responsible for the observed association of the enzyme with chloroplast envelopes in vitro. This C-terminal extension (29 or 30 residues) may be susceptible to proteolytic cleavage thereby leading to a conversion of chloroplast GAPDH isoenzyme I into isoenzyme II. Evolutionary rate comparisons at the amino acid sequence level show that chloroplast GapA and GapB evolve roughly two-fold slower than their cytosolic counterpart GapC. GapA and GapB transit peptides evolve about 10 times faster than the corresponding mature subunits. They are relatively long (68 and 83 residues for pea GapA and spinach GapB respectively) and share a similar amino acid framework with other chloroplast transit peptides.

Rapid antidepressant response to alprazolam in depressed patients with high catecholamine output and heterologous desensitization of platelet adenylate cyclase

The present study examined the relationship between 24-hr urinary catecholamine (norepinephrine and epinephrine) output and measures of platelet adenylate cyclase (AC) activity in depressed patients (n = 17) and control subjects (n = 10). In both groups, significant inverse correlations were observed when 24-hr urinary catecholamine levels were examined in relation to measures of both receptor-mediated (prostaglandin D2 and alpha 2-adrenergic) and postreceptor-mediated (NaF) platelet AC enzyme activities, suggesting that circulating catecholamines may regulate platelet AC by heterologous (agonist-nonspecific) desensitization of the AC enzyme complex. Depressed patients who had favorable antidepressant responses to alprazolam had significantly higher pretreatment urinary catecholamine output and lower receptor-mediated platelet AC enzyme activities than control subjects, whereas the nonresponders did not. After 8 days of treatment with alprazolam, urinary catecholamine levels declined significantly. In responders, receptor-mediated measures of platelet AC activity increased significantly by day 8 to values comparable to those in control subjects; but similar changes were not observed in nonresponders. Prior to treatment, responders showed a strict linear relationship between receptor-mediated (prostaglandin D2) and postreceptor-mediated (NaF) stimulation of platelet AC activity through the stimulatory guanine nucleotide regulatory protein (Ns), whereas nonresponders did not. This suggests the presence of two distinct coupling interactions between platelet prostaglandin D2 receptors and the stimulatory guanine nucleotide regulatory protein in responders and nonresponders to the antidepressant effects of alprazolam prior to treatment. The authors propose that catecholamines, possibly acting through prostaglandins, may regulate platelet AC enzyme activity by heterologous desensitization occurring through postreceptor mechanisms.

Comparison of severe and mild tardive dyskinesia: implications for etiology

Nineteen patients with severe tardive dyskinesia were compared with 45 patients with mild tardive dyskinesia on demographic and treatment variables. Age, sex, duration and number of psychiatric hospitalizations, and amount and duration of neuroleptic treatment did not discriminate between mild and severe tardive dyskinesia. Severe tardive dyskinesia patients were treated with significantly (p less than .01) fewer neuroleptics and had significantly (p less than .05) shorter neuroleptic-free periods. Onset was more rapid in severe tardive dyskinesia patients than in mild tardive dyskinesia patients. Severe tardive dyskinesia is more likely t result from greater patient vulnerability than from heavier neuroleptic exposure. Unipolar depressed patients who are older and on higher neuroleptic dosages may be more susceptible to severe tardive dyskinesia.

Clinical forms of severe tardive dyskinesia

The authors describe 19 patients with severe tardive dyskinesia, 11 of whom had a diagnosis of affective or schizoaffective disorder rather than schizophrenia. Most patients had been receiving long-term neuroleptic treatment with few interruptions and had received only one or two different neuroleptics. Frequent eye blinking was the most prevalent prodromal sign of tardive dyskinesia (in seven patients). Four subtypes of tardive dyskinesia could be distinguished: choreoathetosis, tardive dystonia, blepharospasm, and tardive akathisia. Optimal pharmacotherapy most often consisted of combinations of neuroleptics, lithium carbonate, benzodiazepines, and antiparkinsonian drugs. However, after an average of 62 months, only five patients had markedly improved.