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D Platt

Publications and source records attributed to D Platt.

At least 19 recordsLinked to original sources
PubMed1992

High-performance liquid chromatographic method for the determination of alprazolam in plasma using the column-switching technique.

A reversed-phase high-performance liquid chromatographic method is described for the quantitative determination of alprazolam in the plasma of geriatric patients in the presence of 4-hydroxyalprazolam, alpha-hydroxyalprazolam, bromazepam, oxazepam, lorazepam, clobazam, desmethylclobazam, diazepam and desmethyldiazepam. The procedure is based on the enrichment of alprazolam on a PRP-1 pre-column, followed by the transfer of the compound in a forflush mode to the analytical column. Alprazolam can be quantified reliably down to a minimum concentration of 1 ng/ml of plasma.

Aged↗
PubMed1992

[Intensive care medicine in advanced age from the viewpoint of the internist].

BASIC REMARKS: The percentage of elderly patients in ICUs has doubled over the last 20 years; in the case of the over-seventy-year-olds it is at present about 30%. MAJOR DISCUSSION POINTS: The mean length of stay in the ICU and hospital, and the average costs incurred, are not significantly higher in the case of the elderly. With increasing age, mortality rises steadily, being about 20% for geriatric patients in the ICU, 37% in hospital, and 52, cumulative, after one year. Nevertheless, elderly patients benefit in particular from intensive care. Their relative mortality rate in comparison with the general population of the same age is only slightly elevated. In view of the very high mortality following cardiopulmonary resuscitation of geriatric patients, it would make good sense to limit the indication in particular cases. Quality of life after discharge from ICU care and thereafter is appreciably lower in comparison with younger patients, but acceptance of intensive care is very good among elderly patients, too. As a study we carried out in our "toxicological" ICU showed, prognostic scoring systems for the elderly are not particularly reliable, and the geriatric skills and the knowledge of the physician weigh heavier. CONCLUSIONS: We consider intensive care in the elderly to be both beneficial and efficient, for despite an increase in the mortality rate, a satisfactory quality of life is achieved.

Aged↗
PubMed1992

Dynamics of gene expression for microtubule-associated protein MAP1B, embryonic alpha-tubulin and late neural beta-tubulin mRNAs in the hippocampus of aged rats.

In the present study we characterized the developmental changes in the prevalence of mRNA coding for microtubule-associated protein, MAP1B, embryonic alpha-tubulin and late neural beta-tubulin in rat hippocampus and forebrain from 1 to 720 days of age using RNA gel-blot analysis. We find that (i) the microtubule-associated protein, MAP1B, signal was relatively abundant at early postnatal stages when compared with mature animals. The hybridization signal in the 24-month-old rats was was approximately 1.7 times that observed in 6-month-old rats. (ii) Embryonic alpha-tubulin and late neural beta-tubulin were differentially regulated during rat brain development. This regulation is characterized by a dramatic decrease in the amount of alpha-tubulin after day-1 and a coincident increase in the production of late neural beta-tubulin. Both messages became stabilized at moderate levels during the subsequent developmental stages. However, the averaged signal for beta-tubulin was then approximately 1.8-fold increased in 24- vs. 6-month-old rats. These results are consistent with hypothesis of an age-associated increase in reactive synaptogenesis where the healthy neurons sprout new connections to compensate for neuronal loss occurring in neighboring neurons.

Aging↗
PubMed1992

Modulation of the lung colonization of B16-F1 melanoma cells by citrus pectin.

CONTEXT: Studies have shown that the galactoside-containing simple sugars and anti-galactoside-binding lectin antibodies may affect experimental tumor cell metastasis. However, the limited number of reagents used thus far necessitate further observations. PURPOSE: Natural citrus pectin (CP) and pH-modified CP (MCP), rich in galactose residues, were used to study the involvement of carbohydrates containing galactoside residues in cellular interaction in vitro and in lung colonization in vivo of B16-F1 melanoma cells. METHODS: B16-F1 melanoma cells were incubated with various concentrations of CP and MCP. Their ability to form homotypic aggregation in vitro and tumor lung colonization in vivo in 8-week-old female C57BL/6 mice was then analyzed. RESULTS: The CP binds to the surface of B16-F1 melanoma cells; this binding can be inhibited by lactose at a concentration of 0.15 M. Intravenous injection of the murine B16-F1 melanoma cells with the natural CP resulted in a significant increase (up to threefold) in the appearance of tumor colonies in the lung and in increased homotypic aggregation properties of the cells, while injection of MCP significantly decreased B16-F1 experimental metastasis (greater than 90%). CONCLUSIONS: Tumor galactoside-binding proteins mediate cellular recognition by linking oligosaccharides with terminal D-galactoside residues on adjacent cells. Successful interference with such a process with MCP may lead to a reduced ability to form tumor cell emboli and metastasis. IMPLICATIONS: These findings imply that the galactose-containing carbohydrate side chains of CP might mimic or compete with the natural ligand(s) of the tumor galactoside-binding protein (gal-lectin) and thus affect cellular interactions relevant for metastasis.

Animals↗
PubMed1992

The influence of hydrochlorothiazide on the pharmacokinetics of enalapril in elderly patients.

In a randomized, cross-over, single-dose study of 19 elderly hypertensive patients (aged 62-84 y, SBP greater than 160 mmHg, DBP greater than 100 mmHg, creatinine clearance 11-93 ml.min-1) we have studied the pharmacokinetics of the angiotensin converting enzyme (ACE) inhibitor enalapril after a single oral dose of either 10 mg enalapril or 10 mg enalapril + 25 mg hydrochlorothiazide. The pharmacokinetics of enalapril were unaffected by hydrochlorothiazide, but there was a significant reduction in renal clearance and a significant increase in AUC(0-24 h) of enalaprilat after hydrochlorothiazide, resulting in higher serum concentrations of the active drug. This was independent of the individual degree of renal impairment and might be due either to an initial reduction of GFR by hydrochlorothiazide or to interference with the tubular secretion of enalaprilat. The relationships between serum enalaprilat and serum ACE activity were similar after both treatments, both consistent with a value for Ki of enalaprilat of about 0.1 nmol.l-1. Thus, serum ACE activity was not affected by hydrochlorothiazide but completely reflected the pharmacokinetics of enalaprilat in both treatments.

Administration, Oral↗
PubMed1992

Decortication and striatal mRNA: increases of mRNA for fibronectin, but not of NCAM or alpha-1 tubulin.

Ipsilateral frontal cortex lesions damaged the corticostriatal input. Northern hybridization analysis showed increases in fibronectin (FN) mRNA, but not changes in mRNA for neural cell adhesion molecule (NCAM), neuro-filament-68 (NF-68) or alpha-tubulin (alpha-1T) 72 h post-lesion. In situ hybridization resolved a different spatial-temporal distribution. The superficial cell layer beneath the wound cavity showed transient elevations of FN mRNA that peaked at 72 h post-lesion. However, in the ipsilateral striatum, FN mRNA was maximal at later times than in the wound cavity, at 240 h post-lesion. Changes in NCAM and alpha-tubulin mRNAs in response to decortication occur only around the wound cavity but not in the deafferentated striatum. The different time courses of mRNA revealed by Northern blot analysis and in situ hybridization are most probably due to contamination of the ipsilateral striatum at dissection with superficial tissue adjacent to the wound cavity. These results suggest that cellular responses to ipsilateral decortication consist of two phases: (i) a wound healing process; and (ii) striatal responses to deafferentation.

Animals↗
PubMed1991

Garlic.

Explore the source record for details and available documents.

Aged↗
PubMed1991

[Lipoprotein metabolism in menopause. Effect of hormonal substitution therapy].

Oral administration of conjugated estrogens, estradiol valerate and micronized estradiol--but not the percutaneous application--in the postmenopause modifies the plasmic lipoprotein profile by lowering, dose-dependently, LDL and elevating HDL (HDL2). In parallel, the cardiovascular mortality is decreased by 50-66%, with smokers also benefiting to the same extent. On account of the increased risk for endometrial carcinoma associated with postmenopausal estrogen monotherapy, combination with a lowest-dose gestagen is imperative. However, the very numerous synthetic gestagens can antagonize the favorable effects of the estrogen on lipoprotein metabolism. This applies in particular to the gestagens of the 19-nortestosterone type, such as norethisterone acetate and, in particular, levonorgestrel, but less so the 17-hydroxyprogesterone derivatives medroxyprogesterone acetate and medrogestone with their very low androgenic effect.

Aged↗
PubMed1991

The use of intravenous immune globulin in organ transplantation.

There are no comparative clinical data to differentiate the available IVIG products. Cost, pharmaceutical considerations, and CMV titers are criteria for selecting these products. CMV-IGIV has higher titers of CMV antibodies but is more costly. The potential for CMV infection in transplant patients is great, but the clinical significance may vary. Likewise CMV morbidity and mortality is variable and dependent on the type of transplant, the donor, and immunosuppressive regimens used. IVIG has a role in decreasing CMV infections in transplant patients, but further study and cost-benefit analysis is necessary to determine optimal regimens.

Cytomegalovirus Infections↗