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Biomedical subjects

J M Klein

Publications and source records attributed to J M Klein.

At least 37 records · Page 2Linked to original sources
PubMed1993

Structure and localization of mRNA encoding a pigment dispersing hormone (PDH) in the eyestalk of the crayfish Orconectes limosus.

The pigment-dispersing hormone (PDH) is produced in the eyestalks of Crustacea where it induces light-adapting movements of pigment in the compound eye and regulates the pigment dispersion in the chromatophores. To study this hormone at the mRNA level, we cloned and sequenced cDNA encoding PDH in the crayfish Orconectes limosus. The structure of the PDH preprohormone consists of a signal peptide, a PDH precursor-related peptide (PPRP) and the highly conserved PDH peptide at the carboxy-terminal end. In situ hybridization in combination with immunocytochemistry revealed four cell clusters expressing PDH in the optic ganglia of the eyestalk. Three clusters stained both with the PDH cRNA probe and the PDH antiserum, however, the perikarya in the lamina ganglionaris (LG) only stained with the PDH antiserum, suggesting the presence of a PDH-like peptide in the LG.

Amino Acid Sequence↗
PubMed1993

Transient improvement of congenital lactic acidosis in a male infant with pyruvate decarboxylase deficiency treated with dichloroacetate.

A comatose male newborn infant with congenital lactic acidosis caused by pyruvate decarboxylase deficiency was treated with dichloroacetate (DCA), which stimulated an 88% drop in serum lactate concentration and reversed his coma. The response to DCA was temporary and the lactic acidosis worsened until his death, but DCA may confer more lasting benefit in less severely affected infants.

Acidosis, Lactic↗
PubMed1993

Androgen regulation of epidermal growth factor receptor binding activity during fetal rabbit lung development.

Fetal lung development progresses in a sex-specific manner with male fetuses exhibiting delayed maturation. Androgens, both exogenous and endogenous, inhibit while epidermal growth factor (EGF) enhances fetal lung development. We hypothesized that one mechanism responsible for the delay in male fetal lung development is an androgen-induced delay in EGF receptor binding activity. We measured EGF binding in sex-specific fetal rabbit lung plasma membranes isolated from control fetuses (days 21, 23, 25, 27, 29, and 30 of gestation) and from androgen-treated fetuses (days 21, 23, and 27 of gestation) that had been continuously exposed in vivo to exogenous 5 alpha-dihydrotestosterone from day 12 through 27 of gestation. Specific binding of EGF was significantly lower in male than in female fetal lung tissue isolated from controls at day 21 of gestation. Scatchard analysis revealed that this decrease in EGF binding was associated with decreased EGF receptor density without any significant change in affinity. Prenatal exogenous androgen treatment led to decreased EGF binding in fetal rabbit lung tissue from both sexes secondary to a decrease in EGF receptor density. These findings suggest that one mechanism responsible for the delay in male fetal lung maturation is an androgen-induced delay in EGF receptor binding activity during fetal lung development.

Androgens↗
PubMed1993

Expected endings and judged duration.

In four experiments, the predictions of an expectancy/contrast model (Jones & Boltz, 1989) for judged duration were evaluated. In Experiments 1 and 2, listeners estimated the relative durations of auditory pattern pairs that varied in contextual phrasing and temporal contrast. The results showed that when the second pattern of a pair either seems to (Experiments 1 and 2) or actually does (Experiment 2) end earlier (later) than the first, subjects judge it as being relatively shorter (longer). In Experiment 3, listeners heard single patterns in which notes immediately preceding the final one were omitted. Timing of the final (target) tone was varied such that it was one beat early, on time, or one beat late. Listeners' ratings of target tones revealed systematic effects of phrasing and target timing. In Experiment 4, listeners temporally completed (extrapolated) sequences of Experiment 3 that were modified to exclude the target tone. The results again showed that phrase context systematically influenced expectancies about "when" sequences should end. As a set, these studies demonstrate the effects of event structure and anticipatory attending upon experienced duration and are discussed in terms of the expectancy/contrast model.

Adult↗
PubMed1992

Molecular cloning of crustacean pigment dispersing hormone precursor.

The cDNA encoding the precursor of the pigment dispersing hormone (PDH) of the shore crab, Carcinus maenas, was isolated and sequenced. The precursor consists of a putative 22 amino acid signal peptide, a putative 33 residue peptide of unknown function, and the 18 amino acid mature PDH, followed by a Gly residue which serves as a possible amide donor. The deduced mature PDH amino acid sequence is identical to those of Uca pugilator and Cancer magister, previously determined by Edman degradation.

Amino Acid Sequence↗
PubMed1992

Sex-specific differences in rabbit fetal lung maturation in response to epidermal growth factor.

Males and females exhibit different stages of lung development at the same gestation with males lagging behind. We hypothesized that one of the mechanisms responsible for the sex-specific difference in fetal lung maturation is a delay in the onset of epidermal growth factor (EGF) activity in the male fetal lung. EGF influences growth and differentiation during development. We studied the effects of EGF on the incorporation of glycerol into lamellar body disaturated phosphatidylcholine (DSPC) in sex-specific fetal rabbit lung explants prepared at 21 and 24 days gestation (term 31 days). The explants were maintained in Waymouth's media + 10% stripped fetal calf serum with or without EGF (10 ng/ml). The incorporation of [1,3-14C]glycerol into lamellar body DSPC was assessed after 3, 5, or 7 days of culture. Female lung explants prepared at 21 days of gestation had increased incorporation of glycerol into DSPC over time in response to EGF treatment. Male lung explants prepared at 21 days did not respond to EGF treatment. In explants prepared at 24 days gestation, baseline glycerol incorporation into DSPC was higher in female as compared to male fetal lung explants. EGF-responsiveness was also sex-specific in these more mature explants, with the male explants now responding to EGF with a consistent increase in the incorporation of glycerol into lamellar body DSPC. We conclude that one of the mechanisms responsible for the lag in male fetal lung development is a delay in the onset of EGF activity.

Animals↗
PubMed1992

Neonatal morbidity and mortality secondary to premature rupture of membranes.

PROM is one of the most common complications of pregnancy that has a major impact on neonatal mortality and morbidity. The occurrence of PROM is either directly or indirectly responsible for a large number of premature births and the concomitant mortality and morbidity associated with preterm delivery. PROM turns a pregnancy into a high-risk situation and increases the need for neonatal resuscitation in the delivery room. The incidence of neonatal sepsis increases with PROM, but the overall outcome of the neonate, even with surfactant therapy, is still primarily dependent on the gestational age at the time of delivery. This is most relevant between 24 and 27 weeks' gestation. During this 3-week interval, survival improves by almost 2% for each additional day of in utero maturation (i.e., from 35 to 75%). Thus the benefit to the fetus of prolonging the pregnancy in cases of PROM is immensely worthwhile and should be aggressively pursued as long as there is no significant increase in maternal morbidity.

Female↗
PubMed1991

The evolution of oxidative stress indicators in the course of myocardial ischemia.

Two studies were carried out in patients suffering from Unstable Angina (UA) and Myocardial Infarction (MI). The first study investigated the variations of the Malondialdehyde (MDA) rate at 1st, 5th, 12th day of treatment in 27 patients (15 UA and 12 MI), compared to 15 controls. This rate varied in a different way, with a first peak and a rapid decrease in UA, where it regularly decreases in MI. The second study focused on the variations of MDA, Superoxide Dismutase (SOD), Glutathion Peroxydase (GPX) rates at 2nd, 12th days in 53 patients (19 UA and 34 MI), compared to 35 controls. Here again, the rate of MDA was high on day 2 and decreased on day 12. The rate of GPX showed similar evolution while the SOD rate had an opposite evolution. These two studies confirm the evidence of oxidative stress in acute coronary deficiency.

Aged↗
PubMed1991

[Free radicals and lipid peroxidation in cell biology: physiopathologic prospects].

Oxygen derived free radicals (OFR) arise in the course of normal cellular life, especially during cellular respiration. They are formed when molecular oxygen is reduced to water. These highly reactive species are controlled by a protective system both enzymatic and non enzymatic which helps to prevent the accumulation of peroxidative damage to the cell. Lipid peroxides result from the reaction of oxygen derived free radicals with polyinsatured fatty acids of membranes phospholipids and can be formed both non enzymatically and enzymatically (eicosanoids). Oxygen derived free radicals attack over-running beyond the protective system leads to oxidative stress. The cells involved in inflammation (polymorphonuclear, leucocytes, monocytes, platelets, endothelial cells) release oxygen derived free radicals and lipid peroxides and inflammatory diseases of infectious or non infectious origin can be considered as oxidative stress. Intracellular oxidative stress can lead to cellular death or trigger a strong inflammatory reaction. This occurs during ischemia reperfusion injury and hyperoxia. Exposure to ionizing radiation results in overproduction of oxygen derived free radicals both extra and intracellular. Oxidative stress may be involved in atheroma (where oxidised LDL are described), ageing and cancer.

Animals↗
PubMed1990

Pre-B lymphocytes with intracytoplasmic mu chains in the peripheral blood of rheumatoid arthritis patients.

A dysregulation of B-cell differentiation and activation has long been evidenced in rheumatoid arthritis (RA). Such analyses have, however, usually focused on the latest stages of B-cell development. Using a classical technique of immunofluorescence labeling on cytospins, we investigated the presence of peripheral pre-B lymphocytes in 92 RA patients and 23 controls. Cells with intracytoplasmic mu chains were evidenced in 58.7% of the RA patients studied, ranging between 0 and 30%, while small numbers of c-mu cells, never exceeding 6% of peripheral blood lymphocytes, were observed in 9 controls. Relationships between this feature and clinical or laboratory data were investigated, showing a negative correlation between the percentage of c-mu + lymphocytes and Ritchie's index (P = 0.05), the number of tender or swollen joints (P = 0.05), erythrocyte sedimentation rate (P = 0.005), seropositivity (P = 0.05), and disease duration (P = 0.01).

Adult↗
PubMed1988

Results of serial coronary angiography in patients with homozygous familial hypercholesterolaemia.

We studied the progression of coronary angiographic findings in a series of 10 patients with homozygous familial hypercholesterolaemia. All patients had medical treatment; six had additional surgical treatment. They were followed over a period of 2-10 years (mean follow-up five years). Three types of evolution were observed: (a) normal coronary angiography with no development of any lesion over a period of eight years in two young patients; (b) regression of proximal coronary stenoses in three patients, and (c) progression of coronary angiographic status in five patients. A different evolution of proximal and distal segment lesions was observed; while more than two-thirds of proximal segments stenoses improved and no proximal lesion increased with a 45% decrease in plasma cholesterol level, no improvement was obtained at the distal level. Distal lesions tended to increase and new lesions appeared in spite of a major plasma cholesterol level reduction. When early treatment results in a cholesterol plasma level decrease of more than 45% and a level of about 4 g l-1 over a very long period of time, the coronary prognosis may be good.

Adolescent↗
PubMed1987

[Myocardiopathies of Friedreich's disease].

Cardiac involvement in Friedreich's disease is classically a hypertrophic myocardiopathy, concentric or assymmetrical with or without dilatation. It has nothing specific in comparison to other myocardiopathies. Nevertheless, forms with a dilated myocardiopathy are also possible, but much more unfrequent. A propos of three cases, we have studied the different aspects of myocardiopathies in Friedreich's ataxia. The problem raised by the case of an hypertrophic myocardiopathy evolving toward a dilated form, unusual element of this pathology, is presented. The therapeutic potential of hypertrophic myocardiopathies is classically represented either by beta-blockers or by the more recent slow calcium inhibitors.

Adult↗
PubMed1987

[Flecainide by the intravenous route: a new method for decreasing auricular fibrillation].

The action of intravenous flecainide was studied in patients presenting a tachyarrhythmia secondary to a permanent atrial fibrillation of recent onset. We obtained 9 improvements in 15 patients included in the protocol which consisted in the intravenous injection of 2 mg/kg of flecainide in 10 minutes. The side effects were minimal: no sign of cardia insufficiency nor alteration of the arterial blood pressure was noted. Nevertheless, although interesting, this method to decrease atrial fibrillation is not, in our opinion, destined to replace external electrical shock, except in some special cases.

Adult↗
PubMed1987

[Embolic intracardiac thrombosis on a catheter for permanent stimulation. An echocardiographic finding].

If endovenous thromboses on permanent cardiac stimulation catheter are rather frequent, it is usual to note the absence of complications, especially embolic complications. On the contrary, intracardiac thromboses, occurring always on a permanent stimulation catheter, are rare but may generate embolisms: the authors report a new case discovered on bidimensional sonocardiography recorded following pulmonary embolisms.

Aged↗
PubMed1986

[Residual arterial hypertension after excision of an extra-adrenal pheochromocytoma].

Residual arterial hypertension after excision of a pheochromocytoma of the Zuckerkandl organ, has brought the problem of its etiology. The short term approach consisted in performing, after specific biochemical dosages, a scintigram with IMBG, a scan and a magnetic resonance imaging, to look for a second pheochromocytoma. A negative workup enabled to conclude to an essential arterial hypertension. Nevertheless, this does not exclude the possibility of a long term malignancy, requiring clinical monitoring and IMBG scintigraphy.

Chromaffin System↗