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Biomedical subjects

J Potter

Publications and source records attributed to J Potter.

At least 73 records · Page 4Linked to original sources
PubMed1997

Influenza vaccination of health care workers in long-term-care hospitals reduces the mortality of elderly patients.

Vaccination of health care workers (HCWs) is recommended as a strategy for preventing influenza in elderly patients in long-term care. However, there have been no controlled studies to show whether this approach is effective. During the winter of 1994-1995, 1059 patients in 12 geriatric medical long-term-care sites, randomized for vaccination of HCWs, were studied. In hospitals where HCWs were offered vaccination, 653 (61%) of 1078 were vaccinated. Vaccination of HCWs was associated with reductions in total patient mortality from 17% to 10% (odds ratio [OR], 0.56; 95% confidence interval [CI], 0.40-0.80) and in influenza-like illness (OR, 0.57; 95% CI, 0.34-0.94). Vaccination of patients was not associated with significant effects on mortality (OR, 1.15; 95% CI, 0.81-1.64). Results of this study support recommendations for vaccination against influenza of HCWs in long-term geriatric care. Vaccination of frail elderly long-term-care patients may not give clinically worthwhile benefits.

Aged↗
PubMed1997

Nutrition and other risk factors for renal cell carcinoma in postmenopausal women.

Among 35,192 postmenopausal, predominantly white women in Iowa age 55-69 years and free of cancer, we collected baseline history, dietary information, and anthropometric data by mail in 1986. We ascertained the 8-year incidence (62 new cases) of renal cell carcinoma using the Iowa Surveillance, Epidemiology, and End Results (SEER) register, the National Death Index, and mail follow-up. Risk factors for renal cell carcinoma included increasing age, increasing weight (either current, maximum adult weight, or weight at ages 18, 30, or 50 years), greater waist-to-hip ratio, and a history of blood transfusion. Total dietary calcium was associated independently with a reduced risk of renal cell carcinoma. No other dietary micro- or macronutrients or food groups were predictive of the development of renal cell carcinoma. Other previously identified risk factors were not confirmed: most notably, there was no increased risk from a history of hypertension, after adjustment for diuretic use. History of ever-use of diuretics was associated with a twofold increased risk of renal cancer, although the strength of association was markedly reduced after adjustment for age, weight, waist-to-hip ratio, and calcium intake.

Adult↗
PubMed1997

Understanding the unmanageable nursing unit with casemix data. A case study.

The unmanageable nursing unit is one that has the reputation of being wastefully over budget, not using nursing resources well, not cost effective, and certainly not well managed. Serendipity led us to discover ways to understand the unmanageable unit in one institution. The nurse manager knew the unit was not working well, but had no way to describe this in clinical management terms that would be understood by others. When data from before and after major structural and system redesign initiatives became available, they showed a situation in which decisions were made without data that worked. How much better might it have been had the data that was now accessible been used? We suggest a design for using standard hospital data to define alleged problems of inefficient nursing units, the design is also the structure for monitoring the effects of management changes.

Connecticut↗
PubMed1997

Cardiopulmonary and arterial baroreflex-mediated control of forearm vasomotor tone is impaired after acute stroke.

BACKGROUND AND PURPOSE: Elevated blood pressure (BP) levels are well recognized after acute stroke and are associated with increased BP variability. The underlying mechanisms producing such changes are unclear but may include abnormalities of baroreceptor-mediated control of heart rate and vasomotor tone. Lower body negative pressure (LBNP) can be used to assess the integrity of "low-pressure" cardiopulmonary and "high-pressure" arterial baroreceptor-derived responses by inducing nonhypotensive and hypotensive stimuli. METHODS: Cardiovascular responses, including BP, heart rate, forearm blood flow, and forearm vascular resistance, to nonhypotensive and hypotensive LBNP were assessed in 13 consecutive stroke patients. Patients were studied within 72 hours of stroke (acute) and again at 10 to 14 days (subacute) and were compared with 13 control subjects individually matched for age, sex, and BP. RESULTS: At an LBNP of -10 mm Hg, BP was unchanged in all groups, but a significant increase in forearm vascular resistance occurred only in the control group (11 U [interquartile range, 7 to 15]; P < .05) compared with stroke patients in the acute (9 U [3 to 14]; P = NS) or subacute phases (7 U [2 to 12]; P = NS). After LBNP at -40 mm Hg, the reductions in systolic BP levels were similar in all groups (control: -9 mm Hg [-16 to -3]; acute stroke: -9 mm Hg [-22 to 3]; subacute stroke: -7 mm Hg [-35 to 20]), as was the associated increase in heart rate (control: 8 bpm ([4 to 11]; acute stroke: 6 bpm ([1 to 12]; subacute stroke: 9 bpm [2 to 19]). However, forearm vascular resistance increased significantly only in control subjects (20 U [9 to 30]; P < .01). CONCLUSIONS: The present study has identified abnormal vasomotor responses to LBNP after acute stroke, with an increase in FVR only being observed in control subjects in response to nonhypotensive and similar hypotensive levels of LBNP. In acute stroke patients, the stimulus of hypotensive LBNP appears to be compensated by an increase in cardiac output since there appears to be no increase in peripheral vascular resistance, unlike the changes seen in control subjects. However, the exact mechanisms for these changes are still unclear and are the subject of further study.

Acute Disease↗
PubMed1997

Cardiac baroreceptor sensitivity is impaired after acute stroke.

BACKGROUND AND PURPOSE: The blood pressure (BP) fall and increased BP variability after acute stroke have been previously described. The underlying pathophysiological mechanisms producing these findings are unclear but may include abnormalities of cardiac baroreceptor reflex arc and/or changes in sympathetic nervous system activity. To date, evidence of impaired cardiac baroreceptor sensitivity (BRS) after stroke is limited to patients with chronic disease as determined by invasive methodology. Therefore, it was proposed to assess cardiac BRS and sympathovagal balance with the use of novel noninvasive techniques after acute stroke. METHODS: Thirty-seven acute stroke patients underwent simultaneous surface electrocardiographic and noninvasive beat-to-beat BP recording. Cardiac BRS was assessed by power spectral analysis techniques, and sympathovagal balance was determined from the ratio of the low- to high-frequency powers for pulse interval variability. The responses were compared with a control group matched for age, sex, and BP. RESULTS: Median cardiac BRS was significantly lower in stroke patients than in control subjects (high-frequency alpha-index, 4.89 versus 6.50 ms/mm Hg; P = .007; combined alpha-index, 4.65 versus 5.46 ms/mm Hg; P = .02). Median normalized high- but not low-frequency power of systolic BP variability was significantly greater in stroke patients (11.0 versus 6.7 normalized units; P < .001), probably reflecting differences in the mechanical effects of respiration on BP in stroke patients. No significant differences were observed in the power spectrum of pulse interval variability between stroke patients and control subjects. Patients with tight hemisphere strokes, however, had a significant reduction in median high-frequency pulse interval power compared with patients with left hemisphere strokes (8 versus 20 normalized units; P = .03), which may reflect a change in sympathovagal balance in favor of increased sympathetic tone in this group. CONCLUSIONS: The impairment of cardiac BRS may be important in explaining the increased BP variability after stroke. There was no significant difference in surrogate measures of sympathovagal activity between acute stroke patients and control subjects, but right hemisphere stroke patients had a significant alteration in the sympathovagal balance of pulse interval variability compared with left hemisphere stroke patients. This sympathetic predominance in right hemisphere strokes may be important in the development of cardiac arrhythmias after stroke. The prognostic implications of these findings need to be further explored.

Acute Disease↗
PubMed1997

Orthostatic blood pressure changes on prolonged standing in elderly hospital in-patients.

To determine early and delayed orthostatic BP responses in elderly hospitalized patients on prolonged standing, 85 patients, including normotensive and hypertensive persons, both treated and untreated, aged between 60 and 90 years, were studied. Following 10 min rest a series of nine supine BP measurements were undertaken, first with a mercury sphygmomanometer, immediately followed by an automatic oscillometric BP monitor (SpaceLabs 90207), then again by the sphygmomanometer. Patients then stood and the series of BP measurements was repeated, giving a total of nine standing BP determinations at 1 min intervals. Orthostatic BP measurements recorded by both devices were assessed at 1-3 min (early phase), 4-6 min (mid-phase), and 7-9 min (late phase). The orthostatic fall in SBP was greater during the late than early phase when measured by both the sphygmomanometer (-7.5+/-14.9 vs -2.6+/-10.3 mmHg; difference 4.9+/-8.7 mmHg, p<0.001, 95% CI: 3.0, 6.7 mmHg) and the automatic monitor (-3.5+/-16.9 vs 0.5+/-14.5 mmHg, difference 4.0+/-11.6 mmHg; p=0.002, CI: 1.5, 6.5 mmHg). Orthostatic changes in DBP were similar during early and late phases. More patients had systolic orthostatic hypotension (SBP fall > or =20 mmHg on standing) measured by the sphygmomanometer during the late than early phase (19 [22%] vs 6 [7%]; respectively, p=0.009), but not when measured by the monitor (10 [12%] vs 9 [11%], respectively). Many hospitalized elderly patients may exhibit systolic orthostatic hypotension as measured by sphygmomanometry only after prolonged (> or =7 min) standing.

Aged↗
PubMed1996

The tumor suppressor gene Brca1 is required for embryonic cellular proliferation in the mouse.

Mutations of the BRCA1 gone in humans are associated with predisposition to breast and ovarian cancers. We show here that Brca1+/- mice are normal and fertile and lack tumors by age eleven months. Homozygous Brca1(5-6) mutant mice die before day 7.5 of embryogenesis. Mutant embryos are poorly developed, with no evidence of mesoderm formation. The extraembryonic region is abnormal, but aggregation with wild-type tetraploid embryos does not rescue the lethality. In vivo, mutant embryos do not exhibit increased apoptosis but show reduced cell proliferation accompanied by decreased expression of cyclin E and mdm-2, a regulator of p53 activity. The expression of cyclin-dependent kinase inhibitor p21 is dramatically increased in the mutant embryos. Buttressing these in vivo observations is the fact that mutant blastocyst growth is grossly impaired in vitro. Thus, the death of Brca1(5-6) mutant embryos prior to gastrulation may be due to a failure of the proliferative burst required for the development of the different germ layers.

Alternative Splicing↗
PubMed1996

Fibromyalgia and work disability: Is Fibromyalgia a disabling disorder?

Fibromyalgia appears to be an increasingly important source of disability claims and payments. Twenty-five percent of patients seen in rheumatology clinics have received disability payments. Yet fibromyalgia is a clinical rather than a legal construct, and there remain very important limitations regarding the reliability and validity of diagnosis and severity assessments outside of the clinic and in the medicolegal setting. Even so, preparation of disability assessments that cover key requirements can provide substantial assistance to disability adjudicators.

Disability Evaluation↗
PubMed1996

Improvement of debilitating tardive dyskinesia with risperidone.

This case vignette illustrates dramatic improvement of tardive dyskinesia (TD) in an elderly female with a long history of neuroleptic exposure, following treatment with low-dose risperidone. The TD continued to be in remission at 1-year follow-up. This observation calls for well-designed randomized studies to evaluate the efficacy of risperidone in treating TD.

Aged↗
PubMed1996

The quantitation of metabolites of quercetin flavonols in human urine.

The flavonoid quercetin, or its metabolites, inhibit chemical carcinogenesis in rodents and may have a role in the prevention of human cancers. Quercetin exposure in human populations results from the dietary intake of various plant foods; high concentrations of quercetin are found in apples, onions, tea, and red wine. Determination of the relationship between dietary intake and cancer risk depends on the characterization of quercetin intake. The development and use of biomarkers for quercetin intake may provide a basis for the objective classification of this exposure. One possible biomarker is metabolic products of quercetin. We report the development of a high-performance liquid chromatography (HPLC)-based assay for quantitation of quercetin metabolites in human urine. The metabolites include 3,4-dihydroxyphenylacetic acid (homoprotocatechuic acid), metahydroxyphenylacetic acid, and 4-hydroxy-3-methoxyphenylacetic acid (homovanillic acid). The assay has only two major steps, ether extraction and HPLC analysis, and is suitable for analysis of large sample numbers. Analytical characteristics of the assay include a sensitivity of less than 1 microgram, precision with coefficients of variation < 10%, and metabolite recoveries > 90%. The mean concentrations of 3,4-dihydroxyphenylacetic acid, metahydroxyphenylacetic acid, and homovanillic acid in two human urine samples are approximately 0.7, 4.8, and 2.8 micrograms/ml, respectively. The identification of each metabolite is confirmed by HPLC, UV absorbance scans, and gas chromatography-mass spectrometry analysis. These results verify the occurrence of quercetin metabolites in human urine and the feasibility of quercetin metabolite quantitation, by the assay described herein, for epidemiological studies. Development of the analytical procedure is an essential first step for validation of the metabolites as biomarkers of quercetin intake.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1995

Spontaneous resistance to acute T-cell leukaemias in TCRV gamma 1.1J gamma 4C gamma 4 transgenic mice.

The concept of tumour surveillance implies that specific and non-specific components of the immune system eliminate tumours in the early phase of malignancy. The immunological mechanisms that control growth of preneoplastic cells are, however, not known. T cells expressing gamma delta T-cell receptors (TCR) were first described as lymphocytes with reactivity against various tumour cells, which suggests that gamma delta T cells could mediate tumour surveillance. Here we show that TCRV gamma 1.1J gamma 4C gamma 4 transgenic mice are spontaneously resistant to acute T-cell leukaemias but cannot reject non-haematopoietic tumours. TCRV gamma 1.1J gamma 4C gamma 4+ hybridomas isolated from these mice react in vitro against almost all haematopoietic tumour cell lines tested. Recognition of tumour cells depends on the gamma delta TCR but is independent of major histocompatibility complex (MHC) class I, MHC class II, or TAP-2 peptide transporter expression. Ligand recognition is influenced by the murine Nromp gene, which confers resistance or susceptibility to tuberculosis, lepra and leishmaniasis. These data indicate that TCRV gamma 1.1+ T cells confer spontaneous immunity against haematopoietic tumours in vivo and link innate resistance to bacterial infections with tissue-specific tumour surveillance by gamma delta+ T cells.

3T3 Cells↗
PubMed1995

Changes in the sweatspot test with ageing and relation to cardiovascular autonomic function.

The sweatspot test assesses the local sweat response to an intradermal injection of acetylcholine. It has been reported as a more sensitive indicator of autonomic dysfunction in important diabetic men than either pupillary or cardiovascular tests, and has been used to establish the presence of autonomic dysfunction in patients with idiopathic chronic constipation. However, the usefulness of this test as a simple and quick method of diagnosing autonomic dysfunction in an elderly population has not been established. This is important given the high prevalence of reduced autonomic function with ageing and hypertension. We compared the age-associated responses in the sweatspot test and its relation to cardiovascular autonomic function in elderly normotensive and hypertensive subjects. We studied eleven normotensive and 24 untreated hypertensive elderly subjects (mean age 75.7 years, range 63-85) and compared the results of the sweatspot test to a young control group (n = 11, mean age 32.0 years, range 25-41), and to a standard battery of cardiovascular autonomic function tests. The median sweatspot score was significantly lower in the elderly compared with young subjects (1.9 vs. 12.0, p < 0.0001) although there was no difference between elderly normotensive and hypertensive subjects (1.6 vs. 2.4, p = 0.8). No correlation was demonstrated between the median sweatspot score and the number of abnormal cardiovascular tests. The sweatspot test was grossly abnormal in all elderly subjects and was not correlated to changes in cardiovascular autonomic function. Its diagnostic use in the elderly is therefore of very limited value.

Acetylcholine↗
PubMed1995

Energy intake and expenditure in elderly patients admitted to hospital with acute illness.

Studies on hospitalized elderly subjects have demonstrated that negative energy balance is common during hospitalization, but have concentrated primarily on long-stay and psychogeriatric patients. There is little information on energy balance in elderly patients admitted with acute illness from the community, despite the importance of this patient group and the presence of a number of factors likely to predispose such patients to negative energy balance. In the present study energy balance was quantified in twenty patients (eight males, mean age 82 (SD 5) years; twelve females, mean age 84 (SD 6) years) admitted from the community with acute illness, and predicted basal metabolic rate (BMR) was compared with measured resting metabolic rate (RMR). Most patients were in negative energy balance during hospitalization, and median measured energy intake (EI): measured RMR ratio was 1.0 (range 0.7-1.8). The mean difference between measured EI and estimated total energy expenditure was -1.3 MJ/d (range -3.4 to +2.5 MJ/d). Estimated total energy expenditure exceeded measured EI in fifteen of the patients and there was a significant decline in mid-arm muscle circumference (paired t, P < 0.05) during hospitalization. We conclude that moderate negative energy balance is common in this patient group, and that these patients are at risk of undernutrition during their hospital stay.

Acute Disease↗
PubMed1995

The nutritional status and clinical course of acute admissions to a geriatric unit.

Undernutrition of long-stay hospital patients and those in surgical units is well documented. This study was designed to determine the extent of the problem in elderly people admitted to hospital with acute medical problems and to assess the relationship between nutritional status and course of hospital stay. Sixty-nine patients underwent a nutritional assessment on admission and at intervals throughout their hospital stay and episodes of sepsis were documented. Severely malnourished patients were identified using body mass index, BMI (22%) and corrected arm muscle area, CAMA (26%). Episodes of sepsis occurred significantly more often in the severely undernourished group (p < 0.04). The median length of stay of the group was 16 days (range 2-113): during this time there was no significant change in markers of nutritional status apart from actual muscle circumference (AMC), which showed a reduction in measurement between admission and discharge which was statistically significant (p < 0.0003). This study indicated that severe malnutrition is common in elderly medical admissions, and that it is associated with an increased risk of sepsis. Additional nutritional depletion may occur during hospital stay, and is not easily recognized unless anthropometry is undertaken.

Aged↗
PubMed1995

The influence of anesthetic agents on rat hepatic cytochromes P450 in vivo.

The objective of this study was to identify which anesthetics when used acutely will affect cytochrome P450 (CYP) activity in male Sprague-Dawley rats in vivo. The anesthetics tested were fentanyl citrate, alpha-chloralose, ketamine, urethane (ethyl carbamate), halothane, and ether. CO2 anesthesia was used as the control comparator. Theophylline was used as a probe for CYP1A activity, phenobarbital for CYP2B/2C, flecainide for CYP2D1, and ethosuximide for CYP3A activity. All probes were administered via tail vein injection after anesthetic-induced loss of the righting reflex. Single sample probe clearances were estimated, and used as an index of CYP activity. Fentanyl citrate, alpha-chloralose, halothane, and ether did not have statistically significant effects on any of the CYP activities. Ketamine did not significantly affect CYP1 or CYP2B/2C activity. However, it decreased the clearance of flecainide (i.e. CYP2D1 activity) by 13.4% (p < 0.001) and the clearance of ethosuximide (i.e. CYP3A activity) by 17.6% (p < 0.0001). Urethane increased the clearance of theophylline by 91.5% (p < 0.0001), and decreased the clearance of ethosuximide by 40.5% (p < 0.0001) though it did not affect CYP2B/2C or CYP2D1 activities significantly. From this data, we conclude that a single dose of ketamine mildly inhibits the activity of CYP2D1 and CYP3A, and a single dose of urethane strongly inhibits CYP3A but increases CYP1A activity.

Analysis of Variance↗
PubMed1995

What method should be used to define 'night' when assessing diurnal systolic blood pressure variation in the elderly?

Diurnal blood pressure (BP) variation can be assessed by cusums-derived measures and by the day-night BP difference from time-, activity- and diary-defined 'night' periods. Reproducibility of diurnal systolic BP (SBP) variation by these different methods was studied in 19 active elderly normotensives, mean age 68.5 years. Subjects underwent simultaneous 24 h BP (Spacelabs 90207) and activity (Gaehwiler wrist actigraph) monitoring on two occasions (median interval 70 days). On the first occasion, mean diurnal SBP variation was 15.1 +/- 8.1 mm Hg by fixed-time definition of 'night' (22.07). When compared with 22-07 defined 'night' period, actigraph- and diary-defined 'night-time' was significantly reduced (-60 +/- 49, and -48 +/- 51 min, respectively) and consequently diurnal SBP variation was significantly greater at 18.2 +/- 8.1 mm Hg and 17.6 +/- 8.4 mm Hg, respectively. Actigraph recordings were also used to exclude 'night' BP readings associated with activity, but this did not significantly alter the diurnal SBP variation. Cusums-derived circadian alteration magnitude resulted in the greatest value for SBP variation (23.4 +/- 6.7 mm Hg). However, reproducibility of diurnal SBP variation was poor by fixed-time method with a coefficient of variation (CV) of > 50%, and only improved to 40% with diary use. Actigraph measurements, even if used to exclude BP values associated with disturbed sleep, did not improve this further. Cusums-derived measures of diurnal variation slightly improved reproducibility with a CV of 34.6% and may be a better method in the assessment of diurnal BP variation in the elderly.

Aged↗