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Biomedical subjects

S A Margolis

Publications and source records attributed to S A Margolis.

35 records · Page 2Linked to original sources
PubMed1986

Microprocessor-based weight shift monitors for paraplegic patients.

The prevention of pressure sores for patients with spinal cord injuries includes pressure relief through the patient shifting position and, thus, weight. We have designed a microprocessor-based device to mount on the seat of a conventional wheelchair. This device has applications in hospital rehabilitation programs for improving patient care and in research to study the cause and prevention of pressure sores. It can use audible alarms, which can be disarmed, to train patients to regularly shift weight. The device stores in its memory data on the interval between and the duration of weight shifts. The contents of this memory can be transmitted to a laboratory microcomputer system and displayed in tabular, graphical, or histogram formats. This device is more versatile than previous timer-based systems, not only because its timer and alarm parameters easily can be reprogrammed, but especially because it can store and play back detailed data on the patient's performance. The device is powered by rechargeable NiCad batteries, which can last several days without recharging.

Body Weight↗
PubMed1984

Amino acid analysis of angiotensin I by proton nuclear magnetic resonance spectroscopy.

The chemical shifts of the isoleucine and histidine protons of angiotensin I were assigned and the chemical shifts of the protons of the other amino acids in the peptide were confirmed at a field strength of 400 MHz. These chemical shift assignments were used to determine the amino acid composition of angiotensin I. These data were then compared to the amino acid composition which was determined by chromatographic analysis of the peptide hydrolysate. The results obtained by the chromatographic method were similar to those obtained by the NMR method. The standard deviations of the results were similar, indicating that these methods are equally precise. The major advantages of the NMR method are that it permits the recovery of the peptide after completion of the analysis and improves the quantitation of amino acids which are either partially destroyed by the hydrolysis procedure or require special derivatization methods for detection and quantitation.

Amino Acids↗
PubMed1983

The high-performance liquid chromatographic analysis of diastereomers and structural analogs of angiotensins I and II.

Diastereomers, alpha- and beta-aspartic acid forms, and partial sequences of angiotensin I and II were resolved by reversed-phase high-performance liquid chromatography (HPLC). Nearly all of the peptides which were examined contained significant amounts of peptides whose amino acid composition differed from the designated peptide. This chromatographic procedure combined with amino acid analysis clearly offers the investigator a rapid method for analyzing and quantifying the purity of angiotensins which are intended for use as reference substances for radioimmunoassay and biological assay.

Amino Acids↗
PubMed1981

Purified reduced nicotinamide adenine dinucleotide: responses to lactate dehydrogenase isozymes from three cell sources.

Lactate dehydrogenase (LDH, E.C. 1.1.1.27) isozymes from three single-cell sources reacted differently with reduced nicotinamide adenine dinucleotide (NADH) purified to published chromatographic and spectrophotometric specifications and free of inhibitors of LDH, when compared with a commercial preparation of NADH. The activity of LDH-1, purified from rabbit erythrocytes, increased the most with inhibitor-free NADH; the next most stimulated were the LDH isozymes from a control hepatocyte line; but hardly responsive at all were the same isozymes from chemically transformed cells. Thus isozyme composition alone did not account for the range of responses to purified NADH. The commercial preparation of NADH used in these studies contains the Strandjörd-Clayson inhibitors, the most potent group identified in NADH preparations relative to LDH activity. The results suggest that specific molecular differences in individual isozymes contribute to the differential response to the Strandjörd-Clayson inhibitors.

Animals↗
PubMed1977

Lactate dehydrogenase inhibitors in NADH preparations.

The presence of a new lactate dehydrogenase inhibitor on the trailing edge of the NADH peak from chromatography on diethylaminoethyl-celluose [Loshon et al., Clin. Chem., this issue] was verified. It was resolved from the NADH by high-performance liquid chromatography on muBondapak C18. When the new inhibitor was present in a reaction mixture to the extent that, of the initial 260-nm absorbance, about 5% was contributed by the inhibitor, the rate of NADH oxidation by lactate dehydrogenase decreased by 65%. The inhibitor absorbs at 260 and 340 nm, and is different from the Strandjord-Clayson inhibitor [J. Lab. Clin. Med. 67, 144 (1966)] by both types of chromatography. Because this new inhibitor has ultraviolet properties similar to those of NADH and chromatographs with the NADH on DEAE-cellulose, the high-performance liquid chromatographic method must be used to ensure its absence in preparations of NADH used for clinical assay.

Chromatography, DEAE-Cellulose↗
PubMed1976

Purification and analysis of the purity of NADH.

We developed an analytical reverse-phase high-performance liquid chromatographic procedure for rapid assessment of the purity of NADH. The method completely separates adenosine monophosphate and adenosine diphosphoribose from NADH. By use of this analytical technique we found that preparative chromatography on DEAE-cellulose gives NADH that is free from adenine nucleotides as well as other impurities that commonly are present in NADH. The absorbance ratio at 260 and 340 nm of the purified NADH in 1.8 mmol/liter ammonium carbonate is 2.261 +/- 0.002 (+/- 1 SD).

Bicarbonates↗
PubMedDate not supplied

Institutionalized older adults in a health district in the United Arab Emirates: health status and utilization rate.

BACKGROUND: Little is known about the rate of institutionalization and health status of nursing home (NH) type patients living in the Middle East. This study was set in the Al-Ain Medical District, a geographically discrete region of the United Arab Emirates, a country with a developing economy located on the shores of the Arabian Gulf. NH-type patients were defined as people aged 60 years and older who were admitted to a hospital or a long-term institutionalized setting for at least 6 weeks and with no evidence of an expectation of discharge at the time of the evaluation. OBJECTIVE: To determine the clinical, functional, cognitive, and nutritional status of NH-type patients living in a defined community within a developing country. METHOD: Cross-sectional survey. RESULTS: All NH-type patients were identified, and all were included in this study (n = 47, 100% participation rate). All were located within three public institutions, none of which was a dedicated NH facility. The rate of institutionalization was 7.0-14.0 per 1,000 people aged 65 or older. The age distribution was 30% (60-74 years), 49% (75-84 years), and 21% (85+ years). The length of stay was 3.8 years. The female:male ratio was 1.6. All except 1 had a neurological disorder, and 89% had dementia. The cognitive deficits were severe with only 61% alert, 41% able to speak, 17% orientated in place, and 15% orientated in time. The functional status was also poor: 98% received assistance with all instrumental activities of daily living, 85% received assistance with five activities of daily living, and 94% were bed bound. The nutritional status was also impaired with a mean body weight of 45 +/- 14 kg and a mean albumin level of 3.1 +/- 0.6 g/dl. When compared with the USA data from the National Center for Health Statistics, the study population was younger, had a longer length of stay, a lower female:male ratio, a higher rate of neurological diseases and dementia, and were far more dependent and disoriented. The rate of institutionalization was one sixth to one third of that in the USA. CONCLUSION: From these data we concluded that this region has a distinctly different population of institutionalized older people who demonstrate greater impairments in all domains of health status.

Activities of Daily Living↗
PubMedDate not supplied

Preparation of Standard Reference Material 2383 (Baby Food Composite) and use of an interlaboratory comparison exercise for value assignment of its nutrient concentrations.

The preparation of the recently released Standard Reference Material (SRM) 2383 Baby Food Composite and the process used for value assignment of nutrient concentrations are reported. SRM 2383 can be used as a control material when assigning values to in-house control materials and when validating analytical methods for measuring proximates, vitamins, and minerals in baby food and similar matrixes. The SRM was prepared as a commercial baby food would be prepared, with the same ingredients. The Certificate of Analysis for SRM 2383 provides assigned values for concentrations of proximates, vitamins, and minerals for which product labeling is required by the Nutrition Labeling and Education Act of 1990. These assigned values were based on measurements by the National Institute of Standards and Technology (NIST) and/or collaborating laboratories. Assignment of analyte concentrations based solely on analyses by collaborating laboratories is described in this paper. Certified values are provided for retinol, tocopherols, and several carotenoids including total beta-carotene; the certification of and methodology used for measurement of these analytes is discussed in a companion paper (this issue, page 288). Reference values are provided for solids, ash, fat, nitrogen, protein, carbohydrate, calories, vitamin B1, vitamin B2, vitamin B6, niacin, biotin, calcium, phosphorus, magnesium, manganese, iron, zinc, copper, sodium, potassium, and chloride. Reference values for additional carotenoids are reported in the companion paper (this issue, page 288). Information values are provided for iodine, selenium, molybdenum, vitamin D, vitamin B12, folic acid, pantothenic acid, choline, inositol, sugars, total dietary fiber, and 3 classes of fats.

Carbohydrates↗
PubMedDate not supplied

Changing use of the emergency department by the elderly in the United Arab Emirates, 1989 and 1999.

Changes in use by the elderly of the emergency department of a major hospital in Al-Ain in the years 1989 and 1999 were examined. All patients aged 65 years or older who attended the emergency room were included in this cross-sectional survey. Patient numbers rose from 321 in 1989 to 1347 in 1999 with no significant change in the female to male ratio of 0.78 or the mean age of the elderly attendees 72.9 +/- 7.4 years. Attendance rose 5.4 fold while non-urgent attendance rose 14.7 fold, demonstrating rising use but falling illness severity over time.

Age Distribution↗
PubMedDate not supplied

Improving diabetic patients' outcomes in family medicine in the United Arab Emirates.

We evaluated a diabetic mini-clinic by assessing adherence to American Diabetes Association guidelines and changes in glycosylated haemoglobin levels. Of 1063 patients, 721 were multiple attenders. Single and multiple attenders showed no significant differences in age, sex, time since diagnosis or body mass index. Female and male multiple attenders showed significant declines in glycosylated haemoglobin levels over the first 12 and 18 months respectively. After 2 years, these levels were similar to those at entry to the clinic. The clinic's compliance with standard measurement guidelines was high. The diabetic mini-clinic model, which is effective in industrialized countries, was equally effective in this setting.

Ambulatory Care Facilities↗
PubMedDate not supplied

Stabilization of ascorbic acid and its measurement by liquid chromatography in nonfat dry milk.

The determination of ascorbic acid by liquid chromatography (LC) was improved by performing the analysis in the presence of solvents that had been purged with argon to reduce the concentration of oxygen. This methodological modification eliminated the oxidation of ascorbic acid during the chromatographic procedure and reduced the minimum detection level to 1 microgram. Solutions of ascorbic acid have been successfully stabilized for 67 days by addition of dithiothreitol to a deaerated solution of water-acetonitrile (25 + 75 v/v), sealed under argon in amber vials and stored at -20 degrees C. In a second independent study, a procedure for the extraction of ascorbic acid from nonfat dry milk in a single step was developed. The ascorbic acid content of Nonfat Dry Milk (SRM 1549) was determined by LC, using the method of standard additions. The mean ascorbic acid content was 54 +/- 5 micrograms/g of sample. Analysis of variance of the analytical results indicates that there is a significant continual increase in the content of the ascorbic acid in each bottle from first to last sample.

Animals↗
PubMedDate not supplied

Certification of nutrients in Standard Reference Material 1846: infant formula.

In 1996, the National Institute of Standards and Technology (NIST) released Standard Reference Material 1846 (Infant Formula), which can be used as a control material for assigning values to in-house control materials and for validating analytical methods for measurement of proximates, vitamins, and minerals in infant formula and similar matrixes. The SRM was manufactured by preparing a spray-dried formula base containing fat, protein, carbohydrates, and minerals and then combining that formula base with a dry-blend vitamin premix that supplied the vitamins. The Certificate of Analysis for SRM 1846 provides assigned values for concentrations of proximates (fat, protein, etc.), vitamins, and minerals for which product labeling is required by the Infant Formula Act of 1980 and by the Nutrition Labeling and Education Act of 1990. These assigned values were based on agreement of measurements by NIST and/or collaborating laboratories. Certified values are provided for vitamins A (trans), E, C, B2, and B6 and niacin. Noncertified values are provided for solids, ash, fat, nitrogen, protein, carbohydrate, calories, vitamin D, delta-tocopherol, gamma-tocopherol, vitamin B1, vitamin B12, folic acid, pantothenic acid, biotin, choline, inositol, calcium, phosphorus, magnesium, iron, zinc, copper, sodium, potassium, and chloride. Information values are provided for iodine, manganese, selenium, and vitamin K.

Food Analysis↗