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Biomedical subjects

P Mayer

Publications and source records attributed to P Mayer.

At least 127 records · Page 7Linked to original sources
PubMed1993

Persistent chorea after recurrent hypoglycemia. A case report.

In a 72-year-old woman with a 33-year history of diabetes mellitus bilateral chorea had occurred after a series of hypoglycemic comas at the age of 58. The choreiform movements remained untreated, persisted more than 10 years and inspite of intermittent exaggeration were tolerated by the patient. Except for the hyperkinetic movements, neurological examination of this patient was otherwise normal as was cranial computer tomography.

Aged↗
PubMed1993

Review of a novel hematopoietic cytokine, interleukin-11.

The novel stromal cell factor, IL-11, has been reported to have diverse effects on the lymphopoietic and myeloid/erythroid cells in vitro. These include expansion of T cell-dependent Ig-secreting B cells, proliferation and differentiation of megakaryocytic progenitors and of a variety of myeloid and erythroid precursor cells, and multiplication of pluripotential hematopoietic progenitors. In addition, IL-11 inhibits adipogenesis in vitro. In vivo administration of IL-11 elevated the number of circulating neutrophils and platelets and increased the number of megakaryocytes in the spleens of normal mice.

Adipose Tissue↗
PubMed1993

Exact behaviour of single-stranded DNA electrophoretic mobilities in polyacrylamide gels.

We demonstrate the existence of a gel edge effect where the velocity of the samples varies in the first and last centimetres of the gel. In spite of this effect, a differential method of velocity determination leads to exact mobility data. Further analysis against DNA length N and electric field E shows that the molecules always migrate according to an A/N+B(E) law, except in a limited range of E and N, whereas a 1/N1.6 entropic driven regime is found. Below a threshold electric field intensity B(E) varies as E2, in good agreement with the biased reptation mechanism, while at stronger electric fields intensities, B(E) stays constant. This second mechanism is not described by any actual theory, but might be attributed to a geometration-like mechanism. Implications of our findings in sequencing electrophoresis are discussed.

DNA, Single-Stranded↗
PubMed1992

In vivo synergism of recombinant human interleukin-3 and recombinant human interleukin-6 on thrombopoiesis in primates.

Using a primate model, we examined the effect of recombinant human interleukin-3 (rhIL-3) and rhIL-6 on thrombopoiesis in vivo. Administration of 33 micrograms/kg/d of rhIL-3 for 11 to 14 days increased levels of circulating colony-forming units megakaryocyte (CFU-Mk) by approximately 15-fold in five rhesus monkeys without raising their platelet counts. In contrast, administration of 30 micrograms/kg/d of rhIL-6 for 10 days in four animals did not increase CFU-Mk levels but significantly raised platelet counts from a mean pretreatment value of 460 x 10(3)/microL (range 360 to 610) to a mean maximum of 746 x 10(3)/microL (665 to 790) on day 8. If monkeys were pretreated with rhIL-3 (33 or 100 micrograms/kg/d for 11 days) to expand their CFU-Mk compartment, the thrombopoietic effect of rhIL-6 was synergistically enhanced leading to platelet counts above 1,000 x 10(3)/microL (mean maximum value 1,247) in all three primates studied. The sequential administration of rhIL-3 and rhIL-6 might represent a powerful strategy to stimulate thrombopoiesis in vivo.

Animals↗
PubMed1992

Reformulation and drop size of apraclonidine hydrochloride.

We performed a prospective, double-masked, placebo-controlled, six-period, cross-over study in which normal subjects were randomly assigned to treatment and compared three different formulations of apraclonidine hydrochloride (the present commercially available formulation, and formulations with hydroxypropylmethylcellulose or lysolecithin). We also evaluated the efficacy of a 16-microliters and 30-microliters drop size. The magnitude and duration of decrease in intraocular pressure was comparable for all formulations. Most subjects tolerated all formulations well with only a few reporting any side effects. The best-tolerated formulation was 0.5% apraclonidine hydrochloride delivered with a 16-microliters drop size. Dry mouth developed frequently with the commercially available 1% apraclonidine solution. Blurred vision complicated the use of the formulation containing hydroxypropylmethylcellulose. Both dry mouth (P less than .05) and blurred vision (P = .004) were statistically significant side effects.

Adrenergic alpha-Agonists↗
PubMed1992

Assessment of cardiovascular autonomic function: age-related normal ranges and reproducibility of spectral analysis, vector analysis, and standard tests of heart rate variation and blood pressure responses.

To establish normal ranges for assessment of autonomic dysfunction, a battery of cardiovascular reflex tests was performed in 120 healthy subjects aged 15-67 years using a computer-based technique. Tests of heart rate variation (HRV) included 8 measures at rest: coefficient of variation (CV), root mean squared successive difference (RMSSD), spectral analysis of HRV in the low frequency, mid frequency, and high frequency bands in the supine and standing postures; 5 measures during deep breathing: CVb, RMSSDb, Expiration-Inspiration (E-I) difference, E/I ratio, and mean circular resultant of vector analysis; Valsalva ratio, and max/min 30:15 ratio. In addition, the change in systolic and diastolic blood pressure in response to standing and the diastolic blood pressure response to sustained handgrip were determined. The results of all measures, the blood pressure tests excepted, declined significantly with increasing age (r = -0.16 to -0.59; p less than 0.05). Moreover, RMSSD, RMSSDb, and E-I difference decreased considerably with increasing heart rate (r = -0.37 to -0.52; p less than 0.001). The longest and shortest R-R intervals in response to standing were distributed within beats 21-39 and 6-24, respectively. All tests were independent of sex. Log transformation was used to define the age-related lower limits of normal at the 2.3 centile for all tests of HRV, except for the E/I, Valsalva, and max/min 30:15 ratios. The results of these tests had to be analysed using a log(y-1) transformation. The intra-individual reproducibility determined on two consecutive days in 20 healthy subjects and 21 diabetic patients indicated that there were no major differences between the two groups regarding the day-to-day variation of test results, which was highest for the Valsalva ratio. We conclude that: (1) all indices of spectral and vector analyses of HRV are age-dependent and have the advantage of being independent of heart rate; (2) RMSSD, E-I difference, and the 30:15 ratio as it was used previously are not suitable for evaluation of autonomic dysfunction in diabetes; (3) log(y-1) transformation is required to determine age-dependent normal ranges and reproducibility for the three ratios.

Adolescent↗
PubMed1992

Pharmacokinetics and efficacy of structurally related spirohydantoin and spirosuccinimide aldose reductase inhibitors.

1. Six potent aldose reductase inhibitors (ARI), three spirohydantoin (I to III) and three spirosuccinimide (IV to VI) compounds, showed similar IC50 activities in vitro for the inhibition of rat lens aldose reductase, but their ED50 values in diabetic rats varied as much as 20-fold in the lens and 50-fold in the sciatic nerve tissue. Pharmacokinetic studies were undertaken to investigate these findings. Structure-pharmacokinetic relationships were studied following i.v. administration to cynomolgus monkeys. 2. The clearance (CL) of each spirosuccinimide ARI was faster (greater than 5 times) than that of the corresponding spirohydantoin compound. In both series the CL values of the C(4) methyl and methoxy analogues were 4-fold greater than those for the unsubstituted compounds, although the CL values of the methoxy and methyl derivatives in the same series were not significantly different. 3. The volumes of distribution (Vss) of the spirohydantoins were about one-half those of the corresponding spirosuccinimides, and the Vss values of the parent compounds of both ARI series did not differ dramatically from those of their methyl and methoxy analogues. 4. All six compounds were eliminated from plasma in a biexponential fashion. The half-lives (lambda 1 and lambda 2) of the spirohydantoin compounds were much longer than those of the corresponding spirosuccinimide compounds, and the unsubstituted compounds had longer half-lives than their methyl and methoxy derivatives. The longest lambda 1 and lambda 2 half-lives were observed for imirestat, while two of the spirosuccinimides had the shortest half-lives. 5. These results indicate that the relationships observed between the in vitro and in vivo activities of the six ARI can be attributed to structurally dependent differences in metabolic clearance.

Administration, Oral↗
PubMed1991

The natural history of somatosensory and autonomic nerve dysfunction in relation to glycaemic control during the first 5 years after diagnosis of type 1 (insulin-dependent) diabetes mellitus.

The natural evolution of neural dysfunction was studied prospectively over 5 years following diagnosis of Type 1 (insulin-dependent) diabetes in 32 patients aged 12-36 years. Motor and sensory nerve conduction velocities, heart rate variation at rest and during deep breathing, and pupillary function were measured at diagnosis and after 3, 12, 24, 48, and 60 months. Thermal and vibration sensation thresholds were determined after 24, 48, and 60 months of diabetes. Mean HbA1 levels of months 3-60 within the normal range of less than 8.3% (7.3 +/- 0.2%) were observed in 13 patients (Group 1), while a mean HbA1 of months 3-60 greater than or equal to 8.3% (10.0 +/- 0.3%) was found in 19 patients (Group 2). Mean nerve conduction was significantly diminished in Group 2 as compared with Group 1 in at least 4 out of 6 nerves tested during months 12-60 (p less than 0.05). Both tests of heart rate variation were significantly impaired in Group 2 as compared with Group 1 after 24 and 60 months (p less than 0.05), but no differences in pupillary function were observed between the groups. Thermal discrimination but not vibration perception thresholds on the foot were significantly higher in Group 2 than in Group 1 at 40 and 60 months (p less than 0.05). Abnormalities in nerve conduction, thermal discrimination, and heart rate variation, but not vibration perception threshold and the pupillary function tests were significantly more frequent in Group 2 than in Group 1 at 60 months (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

One-year treatment with the aldose reductase inhibitor, ponalrestat, in diabetic neuropathy.

A double blind placebo controlled trial was performed to evaluate the effects of the aldose reductase inhibitor, ponalrestat, on symptomatic diabetic neuropathy. After a 4-week placebo run-in phase, 60 patients were 2:1 randomized to receive either 600 mg ponalrestat or placebo once daily over 12 months. Forty-six patients, 30 of whom were treated with ponalrestat and 16 with placebo, completed the study. Motor and sensory nerve conduction, thermal and vibration sensation thresholds, heart rate variation at rest, E/I ratio, pupillary dilation velocity and pupillary reflex latency were determined at baseline and after 6 and 12 months. Neuropathic symptom scores were assessed every 3 months. Among the fifteen nerve function parameters studied, only trends in favour of ponalrestat were noted for heart rate variation and E/I ratio after 6 months (P = 0.06), but no significant differences between the groups could be demonstrated during the study. No adverse reactions were observed. It is concluded that one-year treatment with ponalrestat has no beneficial effects on symptoms or electrophysiological parameters in diabetic neuropathy.

Aldehyde Reductase↗
PubMed1991

Recombinant murine granulocyte-macrophage colony-stimulating factor augments neutrophil recovery and enhances resistance to infections in myelosuppressed mice.

The ability of recombinant murine granulocyte-macrophage colony-stimulating factor (rmGM-CSF) to protect myelosuppressed mice against lethal infections was evaluated. In mice myelosuppressed by cyclophosphamide, subcutaneously administered rmGM-CSF was a potent stimulus of granulopoiesis by increasing the number of GM-CSF-responsive precursor cells in bone marrow followed by a profound neutrophilia. Neutrophil recovery was augmented by rmGM-CSF in a dose-dependent manner at daily doses of 0.6-5.0 micrograms/mouse. In addition, rmGM-CSF increased the functional activity of circulating neutrophils at similar doses. When rmGM-CSF was administered to neutropenic mice before experimentally induced Pseudomonas aeruginosa, Staphylococcus aureus, or Candida albicans infections, it protected against these lethal infections, resulting in increased numbers of survivors. These data suggest that rmGM-CSF protects neutropenic mice from lethal infections, probably by augmenting neutrophil recovery after myelosuppression and activation of mature cells.

Animals↗
PubMed1991

Service needs of stroke survivors and their informal carers: a pilot study.

This pilot study prepares the way for a controlled evaluation of counselling of disabled stroke survivors and their carers. It assesses feasibility of methods and outcome measures potentially useful in the main study. The study elicited information about the psychological, physical, social and service needs, and the feelings of stroke survivors and their informal carers. Twenty patients and their carers were interviewed separately in their own homes. Results describe research tools which were refined, and demonstrate several unmet needs in the psychosocial domain. The main findings were a requirement for more information about stroke and for counselling in relation to 'care' problems arising out of the disability of stroke disease and the changes in dependency produced.

Aged↗
PubMed1991

Recombinant human interleukin 3 induces proliferation of inflammatory cells and keratinocytes in vivo.

In this preclinical study we investigated the effect(s) of recombinant human (rh) interleukin 3 (IL-3) on hemopoietic differentiation and attempted to evaluate possible clinical side effects of this hemopoietic growth factor. Rh IL-3, derived from either Escherichia coli or Chinese hamster ovary, was administered subcutaneously to 16 rhesus monkeys (by pairs) at different doses (11, 33, and 100 micrograms/kg/day) for 14 days. During the 2nd week of administration white blood cell counts increased 2- to 3-fold mainly because of a dose-dependent elevation of basophils (up to 40% of white blood cells) and eosinophils. In addition, moderate to marked elevations of plasma histamine levels were measured. Transient diarrhea and an erythematous skin rash with generalized cutaneous lesions that was not restricted to the injection sites were present in 3 of 6 animals treated with E. coli-derived rh IL-3 (1 of 2 animals that received 33 micrograms/kg and 2 of 2 that received 100 micrograms/kg) and 2 of 6 monkeys treated with Chinese hamster ovary-derived rh IL-3 (1 of 2 that received 33 micrograms/kg and 1 of 2 that received 100 micrograms/kg), respectively. Histopathologic and immunohistologic evaluation of skin specimens revealed a perivascular mononuclear cell infiltrate interspersed with numerous mast cells. Signs of vasculitis were absent. The density of the perivascular infiltrate correlated not only with the dose of IL-3 but also with the duration of the skin eruption. Moreover, hyperproliferation of basal keratinocytes resulting in acanthosis was observed in lesions persisting for 1 and 4 days as also evidenced by a significant (p less than 0.01) increase in Ki-67 (a proliferation-associated marker)-positive basal keratinocytes.

Animals↗
PubMed1991

[Orientation and stretching of DNA chains during pulsed field gel electrophoresis].

The quantitative analysis of the decay of birefringence accompanying gel electrophoresis leads to the characterization of two phenomena respectively attributed to alignment of the tube and to overstretching of the chain in its tube. The major contribution to the molecular orientation is given by the overstretching which relaxes according to a stretched exponential law. The other process, slow, is characterized by a reptation time and a mean orientation factor in good agreement with the biased reptation model without overstretching.

DNA↗
PubMed1991

Recombinant human interleukin 6 is a potent inducer of the acute phase response and elevates the blood platelets in nonhuman primates.

Human interleukin 6 (IL-6) produced by molecular cloning was administered to nonhuman primates to assess its biological activities in vivo. Rhesus monkeys were treated s.c. with recombinant human (rh) IL-6 at 3 and 30 micrograms/kg body weight/day for 11 days, followed by the administration of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) at 5.5 micrograms/kg/day for 5 days. Serum levels of positively regulated acute phase proteins (APP) (C-reactive protein, alpha 1-antitrypsin, haptoglobin, and ceruloplasmin) increased, whereas negatively regulated APP (prealbumin) decreased in response to rhIL-6 treatment in a dose-dependent manner. Platelet counts rose after a latent period of 4-5 days following the start of rhIL-6 treatment, resulting in a maximum twofold increase above normal levels 2-3 days after the termination of the rhIL-6 treatment. Recombinant human IL-6 treatment induced a two to threefold rise in myeloid progenitor blood cell levels. The subsequent administration of rhGM-CSF to rhIL-6-pretreated animals did not increase the progenitor cell levels in blood above those found with rhGM-CSF treatment alone, indicating that rhIL-6 compared to recombinant human interleukin 3 (rhIL-3) has a minor proliferative effect on hematopoietic precursors in vivo. In conclusion, rhIL-6 was shown to be a potent stimulator of APP and was able to increase the number of platelets in circulation in nonhuman primates.

Acute-Phase Reaction↗
PubMed1990

Agonist-induced desensitization of cholinergically stimulated phosphoinositide breakdown is independent of endogenously activated protein kinase C in HT-29 human colon carcinoma cells.

Activation of M3 muscarinic receptors in HT-29 cells by carbachol rapidly increases polyphosphoinositide breakdown. Pretreatment of these cells with carbachol (0.1 mM) for 5 h completely inhibits the subsequent ability of carbachol to increase [3H]inositol monophosphate ([3H]InsP) accumulation, paralleled by a total loss of muscarinic binding sites. In contrast, protein kinase C (PK-C)-mediated desensitization by incubation with phorbol esters [PMA (phorbol 12-myristate 13-acetate)], leading to a time- and dose-dependent inhibition of cholinergically stimulated InsP release (95% inhibition after 4 h with 0.1 microM-PMA), is accompanied by only a 40% decrease in muscarinic receptor binding, which suggests an additional mechanism of negative-feedback control. Neither carbachol nor PMA pretreatment had any effect on receptor affinity. Incubation with carbachol for 15 min caused a small increase of membrane-associated PK-C activity (15% increase, P less than 0.05) as compared with the potency of phorbol esters (PMA) (3-4-fold increase, P less than 0.01). Long-term incubation (4-24 h) with PMA resulted in a complete down-regulation of cytosolic and particulate PK-C activity. Stimulation of InsP release by NaF (20 mM) was not affected after a pretreatment with phorbol esters or carbachol, demonstrating an intact function of G-protein and phospholipase-C (PL-C) at the effector side. Determination of PL-C activity in a liposomal system with [3H]PtdInsP2 as substrate, showed no change in PL-C activity after carbachol (13 h) and short-term PMA (2.5 h) pretreatment, whereas long-term preincubation with phorbol esters (13 h) caused a small but significant decrease in PL-C activity (19%, P less than 0.05). Our results indicate that agonist-induced desensitization of phosphoinositide turnover occurs predominantly at the receptor level, with a rapid loss of muscarinic receptors. Exogenous activation of PK-C by phorbol esters seems to dissociate the interaction between receptor and G-protein/PL-C, without major effects on total cellular PL-C activity.

Carbachol↗