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Biomedical subjects

D Black

Publications and source records attributed to D Black.

At least 199 records · Page 11Linked to original sources
PubMed1990

Identification of a novel amino acid alpha-tyrosine 93 within the cholinergic ligands-binding sites of the acetylcholine receptor by photoaffinity labeling. Additional evidence for a three-loop model of the cholinergic ligands-binding sites.

The native, membrane-bound, acetylcholine receptor from Torpedo marmorata was photolabeled by the competitive antagonist p-[3H]dimethylaminobenzene-diazonium fluoroborate (DDF) in the presence of the noncompetitive blocker phencyclidine and under energy transfer conditions. The isolated alpha-subunits were treated with cyanogen bromide and fractionation of the resulting fragments yielded three radiolabeled peptides, at the level of which, incorporation of [3H]DDF (i) was equally inhibited by the agonist carbamoylcholine and the competitive antagonist alpha-bungarotoxin and (ii) was insensitive to "scavenging" reagents. Subfragmentation of cyanogen bromide peptide III with omicron-iodosobenzoic acid or trypsin and sequence analysis of the fragments led to the identification of a novel amino acid alpha-Tyr-93 (and possibly Trp-86) as labeled by [3H]DDF in a carbamoylcholine-sensitive manner. alpha-Tyr-93 is conserved in the muscle and neuronal alpha-subunits but not in the other subunits of muscle receptor. This result provides evidence for a site involving at least a third loop of the alpha-subunit amino-terminal hydrophilic domain, in addition to the ones previously identified (Dennis, M., Giraudat, J., Kotzyba-Hibert, F., Goeldner, M., Hirth, C., Chang, J. Y., Lazure, C., Chretien, M., and Changeux, J. P. (1988) Biochemistry 27, 2346-2357). Possible contribution of tyrosine side-chains to the complexation of the quaternary ammonium group of cholinergic ligands is discussed.

Affinity Labels↗
PubMed1990

Slow euthanasia? The deaths of psychogeriatric patients.

Psychogeriatric services reach out to people who are suffering from psychiatric disorders which may persist until death and may bring forward death. It has been suggested that these services should aim at avoiding admitting patients for hospital care whose lives may be ended by the upset of admission or prolonged by inappropriate nursing and medical interventions. A review of the characteristics of patients dying during one year while under the care of a psychogeriatric service showed that one in three died as a psychogeriatric inpatient, the remainder dying at home or as inpatients in a general hospital. Those dying as psychogeriatric inpatients differed in their clinical and social characteristics from those dying elsewhere and it seemed unlikely that they could have been cared for humanely without the resources of the hospital ward. Psychogeriatric practice has many similarities to the work of hospices with other terminally ill patients, but the duration of the terminal illness and the needs arising from it are often more prolonged. Probably the management of dying among psychogeriatric patients will be improved if lessons learnt from other hospice practices are adopted.

Aged↗
PubMed1990

Randomised controlled trial of day patient versus inpatient psychiatric treatment.

OBJECTIVE: To assess the proportion of acutely ill psychiatric patients who can be treated in a day hospital and compare the outcome of day patient and inpatient treatment. DESIGN: Prospective randomised controlled trial of day patient versus inpatient treatment after exclusion of patients precluded by severity of illness or other factors from being treated as day patients. All three groups assessed at three and 12 months. SETTING: Teaching hospital serving small socially deprived inner city area. Day hospital designed to take acute admissions because of few beds. PATIENTS: 175 Patients were considered, of whom 73 could not be allocated. Of the remaining 102 patients, 51 were allocated to each treatment setting but only 89 became established in treatment--namely, 41 day patients and 48 inpatients. 73 Of these 89 patients were reassessed at three months and 70 at one year. INTERVENTIONS: Standard day patient and inpatient treatment. MAIN OUTCOME MEASURES: Discharge from hospital and return to previous level of social functioning; reduction of psychiatric symptoms, abnormal behaviour, and burden on relatives. RESULTS: 33 Of 48 inpatients were discharged at three months compared with 17 of 41 day patients. But at one year 9 of 48 inpatients and three of 41 day patients were in hospital. 18 Of 35 day patients and 16 of 39 inpatients were at their previous level of social functioning at one year. The only significant difference at three months was a greater improvement in social role performance in the inpatients. At one year there was no significant difference between day patients and inpatients in present state examination summary scores and social role performance, burden, or behaviour. CONCLUSIONS: Roughly 40% of all acutely ill patients presenting for admission to a psychiatric unit may be treated satisfactorily in a well staffed day hospital. The outcome of treatment is similar to that of inpatient care but might possibly reduce readmissions. The hospital costs seem to be similar but further research is required to assess the costs in terms of extra demands on relatives, general practitioners, and other community resources.

Acute Disease↗
PubMed1990

Sequencing and expression of complementary DNA for the general transcription factor BTF3.

The initiation of transcription of eukaryotic genes involves the ordered assembly of a multiprotein complex on proximal promoter elements such as the TATA box. In addition to RNA polymerase II (otherwise RNA pol II, RNA polymerase B), four general transcription factors are required for initiation of transcription: BTF1 (also referred to as TFIID) which has recently been cloned from yeast, BTF2, BTF3 and STF. The first step in assembly of the initiation complex is the stable binding of BTF1 to the TATA box, which is facilitated by STF. Neither BTF2 nor BTF3 bind directly to the promoter proximal elements, but BTF3 can form a stable complex with RNA pol II. We recently purified BTF3, which is a protein of relative molecular mass 27,000, but further studies have been hampered by its low abundance in cells. On the basis of sequences from peptides of BTF3, we have now cloned two complementary DNAs, one for a protein (BTF3a) with all the characteristics of purified BTF3, and one for a shorter protein (BTF3b) lacking the first 44 residues of BTF3a and which is transcriptionally inactive, despite its ability to bind RNA pol II.

Amino Acid Sequence↗
PubMed1990

Co-evolution from yeast to mouse: cDNA cloning of the two NF-Y (CP-1/CBF) subunits.

NF-Y is a CCAAT box binding protein critical for the expression of diverse eukaryotic genes. We have purified the A and B subunits of NF-Y and, using microsequencing and PCR technology, have cloned the corresponding cDNAs. NF-YA and NF-YB show stretches of arresting sequence homology to the yeast transcriptional activators HAP2 and HAP3. Unlike their yeast counterparts, however, the two mouse subunits appear necessary and sufficient for CCAAT binding activity. We hypothesize that in the case of NF-Y, DNA binding and dimerization both rely on residues within the homology domains, which include rather suggestive 'half-finger' motifs.

Amino Acid Sequence↗
PubMed1990

Surgeons' knowledge, attitude, and use of preoperative autologous blood donation.

Before a comprehensive educational program on preoperative autologous blood donation was begun, 118 surgeons from three different areas of the country were tested to assess their baseline knowledge and attitude about this practice. Test results were correlated with the percentage of eligible patients that the surgeons actually referred for preoperative donation during a period of observation. The purpose of this preliminary effort was to identify areas in the educational program that required emphasis. Overall, the surgeons' attitude toward preoperative donation was quite favorable, but their depth of knowledge varied. Misunderstandings may have led to diminished use of this service (eg, about 50% didn't realize that many patients with medical conditions or low hematocrits are permitted to donate). However, it is not clear that simply bolstering surgeons' knowledge will increase their appropriate use of preoperative donation. When all 118 surgeons were studied, their knowledge and attitude were unrelated to the percentage of eligible patients referred. However, when 44 surgeons who managed the largest number of eligible patients were analyzed separately, their use of preoperative donation was directly correlated with their knowledge and attitude. The local awareness of AIDS also significantly influenced the use of this service. It is proposed that knowledge of preoperative donation may be important for inducing surgeons to begin referring patients for this service. Once a pattern of successful participation is established, referral seems to increase with the acquisition of working knowledge.

Blood Transfusion, Autologous↗
PubMed1990

Procainamide-cimetidine drug interaction in elderly male patients.

Thirty-six hospitalized male patients receiving oral sustained-release procainamide every six hours for the treatment of ventricular arrhythmias were studied at steady-state before and after oral cimetidine 300 mg every six hours for three days. Average age and weight were 73 +/- 12 (SD) years and 76 +/- 10 kg. Patients did not have a myocardial infarction within the last two years or congestive heart failure and had calculated creatinine clearances (CrCl) between 35 and 75 mL/min/70 kg. Ten patients had urine collections that permitted computation of the ratio between the renal clearance of procainamide and CrCl (PA/CrCl) and the renal clearance of n-acetyl-procainamide (NAPA) and CrCl (NAPA/CrCl). The average steady-state procainamide and NAPA concentrations increased 55% and 36%, respectively, during cimetidine treatment (P less than .01). Twelve patients experienced mild to severe symptoms of what may have been procainamide toxicity. Apparent procainamide oral clearance decreased 41% while patients received cimetidine (P less than .01). PA/CrCl and NAPA/CrCl ratios decreased by 33% and 21%, respectively, during cimetidine therapy (P less than .05). Cimetidine therapy given to older male patients taking procainamide can cause steady-state concentrations of procainamide to rise to toxic levels. Patients prescribed this combination should be monitored carefully for adverse side effects.

Aged↗
PubMed1990

Transport of lipid and apolipoproteins A-I and A-IV in intestinal lymph of the rat.

Intestinal lipid absorption is associated with marked increases in the synthesis and secretion of apolipoprotein A-IV (apoA-IV) by the small intestine. Whether the increased intestinal apoA-IV synthesis and secretion results from increased fat uptake, increased cellular triglyceride (TG) content, or increased secretion of TG-rich lipoproteins by the enterocytes is unknown. Previous work from this laboratory has shown that a hydrophobic surfactant, Pluronic L-81 (L-81), is a potent inhibitor of intestinal formation of chylomicrons (CM), without reducing fat uptake or re-synthesis to TG. Furthermore, this inhibition can be reversed quickly by the cessation of L-81 infusion. Thus L-81 offers a unique opportunity to study the relationship between lymphatic TG, apoA-I and A-IV secretion. In this study, we studied the lymphatic transport of TG, apoA-I, and apoA-IV during both the inhibitory phase (L-81 infused together with lipid) and the subsequent unblocking phase (saline infusion). Two groups of lymph fistula rats were used, the control and the experimental rats. In the experimental rats, a phosphate-buffered taurocholate-stabilized emulsion containing 40 mumol [3H]triolein, 7.8 mumol of phosphatidylcholine, and 1 mg L-81 per 3 ml was infused at 3 ml/h for 8 h. This was then replaced by glucose-saline infusion for an additional 12 h. The control rats received the same lipid emulsion as the experimental rats, but without L-81 added, for 8 h. Lymph lipid was determined both by radioactivity and by glyceride-glycerol determination, and the apoA-I and apoA-IV concentrations were determined by rocket electroimmunophoresis assay. L-81 inhibited the rise in lymphatic lipid and apoA-IV output in the experimental rats after the beginning of lipid + L-81 infusion. Upon cessation of L-81 infusion, the mucosal lipid accumulated as a result of L-81 treatment was rapidly cleared into lymph as CM. This was associated with a marked increase in apoA-IV output; the maximal output was about 3 times that of the fasting level. There was a time lag of 4-5 h between the peak lymph lipid output and the peak lymph apoA-IV output during the unblocking phase in the experimental rats. There was also a comparable time lag between the maximal lipid and apoA-IV outputs in the control animals. Incorporation studies using [3H]leucine showed that apoA-IV synthesis was not stimulated during lipid + L-81 infusion, perhaps explaining the lack of increase in lymphatic A-IV secretion.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

The future of hip fractures in the United States. Numbers, costs, and potential effects of postmenopausal estrogen.

Because of the increasing number of elderly people in the United States, the total number of hip fractures in persons 50 years and older will rise from 238,000 to 512,000 by the year 2040, with a concomitant increase in avoidable deaths, disability, and medical costs. The total annual cost of hip fractures (in 1984 dollars) will increase from approximately 7.2 billion dollars currently to 16 billion dollars in the year 2040. Universal use of estrogen therapy by postmenopausal white women may slow but not prevent this rise in hip fractures. New, effective, and widely applicable strategies to prevent hip fractures are urgently needed.

Aged↗
PubMed1989

Risk taking.

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Foodborne Diseases↗
PubMed1989

Risk factors for recurrent nonsyncopal falls. A prospective study.

Falls are a major threat to the health of older persons. We evaluated potential risk factors for falls in 325 community-dwelling persons aged 60 years or older who had fallen during the previous year, then followed up weekly for 1 year to ascertain nonsyncopal falls and their consequences. Risk factors for having a single fall were few and relatively weak, but multiple falls were more predictable. In multivariate analyses, we found increased odds of two or more falls for persons who had difficulty standing up from a chair, difficulty performing a tandem walk, arthritis, Parkinson's disease, three or more falls during the previous year, and a fall with injury during the previous year, and for whites. The proportion of subjects with two or more falls per year increased from 0.10 for those with none or one of these risk factors to 0.69 for those with four or more risk factors. Among older persons with a history of a recent fall, the risk of multiple nonsyncopal falls can be predicted from a few simple questions and examinations.

Accidental Falls↗