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Biomedical subjects

M Schaffer

Publications and source records attributed to M Schaffer.

At least 19 recordsLinked to original sources
PubMed1995

Elevated parathyroid hormone-related peptide levels after human gestation: relationship to changes in bone and mineral metabolism.

PTH-related peptide (PTHrP) can be found in high concentrations in human breast milk and has been implicated in material calcium regulation postpartum. We studied the relationship of plasma PTHrP levels of serum markers of bone turnover and selective cancellous bone density in 35 women (age, 25 +/- 3 yr) 2-3 days postpartum and after 3 and 6 months of lactation. The mean postpartum plasma PTHrP levels measured by immunoradiometric assay was 2.64 +/- 0.19 pmol/L (mean +/- SE) and were elevated compared to that in 35 age- and sex-matched controls (1.34 +/- 0.14; P < 0.0001). PTHrP remained significantly elevated, but decreased during the lactation period of 6 +/- 1 months. Immediately postpartum, serum protein levels were lowest, and serum ionized calcium levels highest. At that time, PTH was suppressed to 50% of control values (P < 0.001). Two or 3 days postpartum, serum ionized calcium was negatively correlated with total serum protein (r = -0.47; P < 0.0001) and positively correlated with plasma PTHrP (r = -0.32; P < 0.008). PTH was inversely correlated with ionized calcium (r = -0.24; P = 0.03) and PTHrP (r = -0.31; P < 0.01). Three and 6 months postpartum, serum protein and PTH levels had returned to normal, and ionized calcium concentrations decreased. There was no indication that PTHrP may have any significant systemic effect after 3 and 6 months of lactation. Long term lactation led to a significant decrease in radial cancellous bone density (-4.5%; P < 0.05) at 6 months and to elevations in serum markers of bone resorption (2- to 3-fold for serum carboxy-terminal telopeptide of type I collagen) and formation (1- to 2-fold for osteocalcin and serum carboxy-terminal propeptide of type I procollagen). Bone turnover balance was clearly negative after 3 months of lactation compared to the control value and indicated net bone loss at a time when estrogen levels were low. With ongoing lactation, estrogen levels increased, and bone turnover balance improved significantly and independently of PTHrP levels. We interpret these results as evidence that PTHrP is elevated during the postgestational period and has a weak and temporary effect on calcium metabolism when serum protein levels are reduced. PTHrP does not seem to participate significantly in the regulation of bone turnover during lactation. Normalization of bone turnover balance at 6 months of lactation suggests that further cancellous bone loss is most likely minimal when breast-feeding is extended beyond that time.

Adult↗
PubMed1992

The influence of the post-Chernobyl fallout on birth defects and abortion rates in Austria.

OBJECTIVES: We analyzed the influence of the radioactive fallout after the Chernobyl disaster on the rate and regional distribution of birth defects and abortion rates in southern Austria. STUDY DESIGN: During 1985 to 1989 a total of 66,743 births was monitored. Twelve sources provided data on 1695 cases of birth defects, 1579 of which were suitable for analysis. All cases were analyzed in terms of their calculated conception date and divided into three main groups according to their vulnerable phase of embryogenesis, spermatogenesis, and oogenesis. To study possible regional changes, the findings were plotted in 17 political subdistricts. The overall abortion rate and the counseling frequency at termination clinics was determined. RESULTS: No significant changes in the incidence of birth defects, abortion rate, or counseling rate at pregnancy termination clinics were observed. CONCLUSIONS: Assessing the teratologic potential of low-dose radiation is difficult and requires adequate grouping of birth defects, sufficient baseline data, and highly reliable registries.

Abortion, Induced↗
PubMed1992

Quantitative determination of Escherichia coli from coliforms and faecal coliforms in sea water.

Escherichia coli concentration in sea water was determined by the MUG test after primary growth on membrane filters used to determine total coliforms or faecal coliforms. A good correlation (r = 0.86) was found between E. coli obtained from coliforms versus those from faecal coliforms. Verification procedures showed that all the MUG-positive colonies obtained on both media were E. coli. Evaluation of this data and the literature indicated that this technique for estimation of E. coli in sea water is a useful addition to laboratory procedures without generally increasing the time and the expense of the analysis of recreational water.

Enterobacteriaceae↗
PubMed1991

Hemolysis due to branch pulmonary stenosis after the arterial switch procedure.

An infant with d-transposition of the great arteries underwent arterial switch operation using the modified Jatene technique. Severe bilateral branch pulmonary artery stenosis and mechanical hemolysis subsequently developed. The hemolysis resolved after surgical repair of the stenotic arteries. Probable causes are discussed.

Anemia, Hemolytic↗
PubMed1990

The narcolepsy-associated DRw15,DQw6,Dw2 haplotype has no unique HLA-DQA or -DQB restriction fragments and does not extend to the HLA-DP subregion.

Almost all patients with cataplectic narcolepsy are DR2-positive. It has been suggested that the non-DR2 allele/haplotype might not be neutral with respect to disease susceptibility. It has also been reported that Taq I DQA and Bam HI, Eco RI, Eco RV, and Pst I DQB restriction fragments might differentiate between narcoleptic and healthy DR2-positive individuals. In the present study, HLA class II gene polymorphisms were investigated by restriction fragment length polymorphism (RFLP) analysis in 47 Swedish patients with cataplectic narcolepsy, 100 random controls, and DR2-associated homozygous cell lines. All patients had Taq I DRB-DQA-DQB patterns corresponding to the DRw15,DQw6,Dw2 haplotype. The non-DR2 haplotype was found to be neutral. This genotyped group of patients allows firm rejection of a recessive mode of inheritance and supports a dominant or additive model. No DQA or DQB RFLPs were found that could differentiate between DR2-positive narcoleptics, DRw15,DQw6,Dw2-positive controls, or Dw2-homozygous cell lines. No significant Msp I HLA-DP association was found. No linkage disequilibrium was observed between the DRw15,DQw6,Dw2 haplotype and alleles of the DP subregion in patients or controls. Thus, the HLA-D region-associated narcolepsy susceptibility gene may be located telomeric to the HLA-DP subregion. No RFLPs have been observed that can locate the narcolepsy susceptibility gene closer to the DQ than to the DR subregion.

Genetic Linkage↗
PubMed1989

[The value of prenatal ultrasound screening exemplified by abnormalities of the urogenital system. Data from the Styrian malformation register 1985 to 1987].

Over a three-year period (1985 to 1987), the number of fetal malformations was entered into Styrian Malformation Register (SMR). The data were compared with those of the Austrian Ministry of Health. The SMR collected 137 cases of urinary tract malformations, but only six appeared in the Health Ministry statistics. This discrepancy resulted from the different data collection methods. Presently only a small percentage of fetal abnormalities is officially registered. Using the example of urinary tract malformations this paper shows the value of prenatal ultrasound screening. Such infants must be treated soon after delivery to avoid progression of parenchymal damage. Ultrasound examinations should not be restricted to pregnant women at defined risk. Registration of all prenatally diagnosed--or missed--malformations is a quality-control measurement and improves prenatal diagnosis.

Austria↗
PubMed1989

A comparison of the age-MLU relation in normal and specifically language-impaired preschool children.

The relation between age and mean length of utterance in morphemes (MLU) was evaluated in a sample of 48 preschool children between 24 and 50 months of age. Twenty-four of these children were diagnosed as having a specific language impairment, and 24 were considered language normal. The groups were matched on age, race, sex, and parental education level. A majority of the children in each group were from lower-middle-class backgrounds. MLU was derived from 20-min mother-child conversations as the dyad engaged in free play. The results showed that (a) age and MLU were significantly correlated in the normal group (r = .75) and in the group of specifically language-impaired children (r = .77), (b) the predicted MLU of the language-impaired group was lower than that of the normal group across the age range, and (c) the rate of MLU change in each group was similar. The age-MLU relation observed in the lower-middle-class normal children compared favorably to that reported previously for middle- to upper-middle-class children (Miller & Chapman, 1981). The finding that MLU changed at a similar rate in the normal and language-impaired groups is evaluated in light of the observation that childhood language disability is usually associated with slower rates of language development.

Age Factors↗
PubMed1988

Quantitative determination of Escherichia coli from faecal coliforms in seawater.

A simple rapid method was developed for counting Escherichia coli in sea water using a membrane filter procedure. Following filtration the membrane filter was incubated on mFC agar medium for 24 +/- 2 h at 44.5 +/- 0.2 degrees C for determination of faecal coliforms. An in situ test for the determination of E. coli was carried out by transferring the membrane filter to nutrient agar containing 4,methyl-umbiliferyl-B-D, glucoronide, followed by incubation for 3 h at 35 degrees C. The E. coli colonies were detected by fluorescence under long wavelength UV light. Extensive biochemical confirmation tests on the isolates showed that all the fluorescence colonies which were either lactose positive or negative were E. coli.

Enterobacteriaceae↗
PubMed1986

A simple method for counting Staphylococcus aureus in swimming pool water.

Staphylococcus aureus counts from swimming pool water were determined by the membrane filtration technique. Water samples were passed through a membrane filter and then put on Baird-Parker media. After incubation, the filters were transferred to nutrient agar, and incubated at 37 degrees C, for 3 h. After removal of the filters, the plates were incubated at 60 degrees C for 2 h. An overlay of toluidine blue agar was added and the plates reincubated for 4 h at 37 degrees C. The formation of thermonuclease correlated with the formation of coagulase, and the results indicated that Staphylococcus aureus could be present in swimming pool water without the presence of either coliform or faecal coliform bacteria.

Enterobacteriaceae↗
PubMed1985

Neuropeptide function: the invertebrate contribution.

The following is a list of generalizations that arise from considering the present state of knowledge concerning the functions of invertebrate peptides. Some of these clearly also apply to vertebrates. Invertebrate peptides can be classified into structurally related groups. Structural similarity of peptides may represent true evolutionary homology by selection acting on an original gene. Alternatively, independent evolution of similar genes may have occurred because certain amino acid sequences represent optimal solutions to complex functional problems. Invertebrate neuropeptides have multiple functions. Thus, proctolin is a cardioactive peptide, a skeletal neuromuscular transmitter, a hindgut neuropeptide, a peptide of CNS interneurons (Keshishian & O'Shea 1984) and may have humoral roles. Invertebrate peptides act through a variety of molecular mechanisms. Generalizations about the mechanism cannot yet be made. Thus, proctolin's action on crustacean skeletal muscle is not associated with stimulation of cyclic-AMP or protein phosphorylation, but the action of SCPB on molluscan skeletal muscle involves elevation of cAMP. Invertebrate peptide inactivation can be caused by proteolysis that can also function to enhance peptide bioactivity. Proctolin is made virtually biologically inactive by any proteolysis, but alpha-BCP bioactivity is enhanced by two steps of carboxy peptidase digestion before being functionally inactivated. Protease action on released peptides is not necessarily a "simple" form of transmitter inactivation. Protease action also involves functional processing whereby the temporal and spatial parameters of a peptide's action may be shaped. Invertebrate neuropeptides are frequently co-localized with other neuroeffectors. Peptides may be co-localized and released with other active peptides as in the bag-cell example, or may be coactive with more conventional transmitters, as in the Ds motoneuron example. In such circumstances there is no reason to view either transmitter as primary or secondary. Invertebrate neuropeptides are widely involved in the control of muscle contraction. These effects may be locally and directly mediated as in the Ds motoneuron example or may be humoral. The peptide may act directly on the muscle contractile system or function to modulate the muscles' response to other motor input. Muscle contraction may be induced by a neuropeptide without depolarization of the muscle cells, for example see proctolin. Invertebrate neuropeptides are frequently involved in the control of oscillatory functions. In several examples peptides activate rhythmic myogenic contractions of cardiac and skeletal muscle.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1984

Fatal maprotiline intoxication.

We report a fatal case of drug toxicity associated with torsade de pointes following an overdose of the tetracyclic antidepressant, maprotiline (Ludiomil). Tissue and plasma levels were obtained at autopsy and are noted. In addition, the cardiovascular effects, pharmacokinetics, and toxicity of maprotiline are reviewed and compared with that of tricyclic antidepressants.

Adult↗
PubMed1984

Isolation and characterization of two myoactive neuropeptides: further evidence of an invertebrate peptide family.

The neuropeptide proctolin acts as a neuromuscular co-transmitter in insect skeletal muscle. As a prelude to determining whether other peptides may function in a similar way, we are attempting to isolate and characterize the chemical nature of new myoactive neuropeptides in insects. We examined the corpus cardiacum, a major insect neurosecretory structure of the American cockroach (Periplaneta americana), using a skeletal muscle bioassay and high pressure liquid chromatography fractionation and identified two myoactive factors, MI and MII. They are synthesized in the corpus cardiacum and released from it into the blood by a calcium-dependent mechanism. Amino acid and fast atom bombardment-mass spectroscopy analysis show that MI and MII are structurally related octapeptides representing the major secreted products of the cockroach corpus cardiacum. Both MI and MII are also present in the CNS and in the gut, indicating transmitter as well as hormonal functions in the cockroach. A survey in other species indicates MI may be present in invertebrates other than insects, but neither was found in the rat. The MI and MII peptides have clear chemical affinities to two previously described invertebrate peptides, locust adipokinetic hormone and crustacean red pigment concentrating hormone, as well as sharing biological activity with these peptides. Our results provide further evidence for the existence of a large family of structurally related peptides with divergent functions in a variety of invertebrate types.

Animals↗