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Biomedical subjects

G Huszar

Publications and source records attributed to G Huszar.

At least 55 records · Page 3Linked to original sources
PubMed1981

Urinary 3-methylhistidine/creatinine ratio as a clinical tool: correlation between 3-methylhistidine excretion and metabolic and clinical states in healthy and stressed premature infants.

We have investigated the role of the urinary 3-methylhistidine (3MH) excretion, a measure of protein catabolism, in the evaluation of the metabolic state of premature infants. Two-hundred and twenty-two 24 hr urine collections and 3MH/Cr ratio determinations (expressed as mumoles of 3MH per mg creatinine) were carried out in 36 infants (average gestational age 32.7 +/- 0.7 wk, weight 1640 +/- 120 grams) and the relationship between the 3MH/Cr ratios and the metabolic and clinical state has been investigated. Five or more 3MH/Cr measurements were carried out on each of 19 infants and serial determinations on four of those babies are presented. The urinary 3MH/Cr ratio of healthy infants with adequate caloric intake and normal growth curve was .148 +/- .039 (S.D.) mumol/mg, about 35% higher than the 3MH/Cr ratio in healthy adults. As long as the premature infants were healthy the degree of prematurity had no effect on the 3MH/Cr ratio. The relationship between 3MH/Cr ratio and nitrogen balance was highly significant (p less than .001). 3MH/Cr ratio also correlates very well with the metabolic status of the infants: in the group with normal 3MH/Cr ratios less than or equal to .175 (.148 + 1 S.D., n = 90) there were four clinically stressed infants (4.4% false negative rate) while in the group with elevated 3MH/Cr ratios greater than .225 (.148 + 2 S.D.; n = 79) there were only three clinically well infants (3.8% false positive rate). In comparing the clinical status and 3MH/Cr ratios, we found that in the group of infants who could not be clearly defined as clinically well or stressed (n = 108) the 3MH/Cr ratio was more useful than clinical judgment in the prediction of metabolic status. It can be concluded that 3MH/Cr ratio is a potentially useful clinical tool which describes with high accuracy the clinical and metabolic status of premature infants. This conclusion is further supported by the data of serial 3MH/Cr determinations.

Birth Weight↗
PubMed1979

Isolation and characterization of myosin in the human term placenta.

The major contractile protein myosin was isolated and characterized from the smooth muscle of human term placentas. Placental myosin originates chiefly in the anchoring villi which bridge the fetal and maternal surfaces of the placenta. The molecular weight of placental myosin is about 460,000; it is composed of two heavy chains of 200,000 molecular weight and two pairs of light chains with 13,500 and 17,500 molecular weights. The adenosine triphosphatase (ATPase) of the myosin is activated by potassium and calcium and it is inhibited by magnesium. Placental actomyosin ATPase is activated by magensium. Contraction and relaxation of the smooth muscle in the anchoring villi are thought to adjust the volume of the intervillous space; thus, actin-myosin interaction is implicated in the regulation of placental hemodynamics.

Adenosine Triphosphatases↗
PubMed1970

[Not Available].

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Dentistry↗
PubMedDate not supplied

Assessment of reproductive disorders and birth defects in communities near hazardous chemical sites. III. Guidelines for field studies of male reproductive disorders.

Exposures to environmental toxicants can have detrimental effects on several aspects of human male reproduction: fertility, sexual function, hormone status, and pregnancy/birth outcomes. However, no simple prescreening methods are available for reliably identifying potential hazards; questionnaires alone are relatively imprecise and inefficient in the absence of field data. Multidisciplinary field studies are required that include detailed exposure information, health and reproductive histories, physical examinations, semen analyses, and possibly, hormone analyses. Semen analysis is a critical component of field studies for evaluating two aspects of male reproduction: 1) changes in sperm or seminal content, which may be indicative of adverse effects on the male reproductive system with possible implications for fertility potential; and 2) defects in sperm DNA or chromosomes, which may be associated with subsequent changes in viability during embryonic development and health risks to the offspring. Semen analyses may be tiered: 1) initially, each semen study may include conventional semen assays (concentration, motility, and morphology) as well as specific biomarkers indicated by the health effect of concern in the study cohort: and 2) archived samples (i.e., frozen, videotaped, or smeared) may be utilized in later second-tier analyses to further characterize specific findings. Before initiating any field study, it is cost effective to critically evaluate the suitability of the cohort by confirming exposure and determining that there are adequate numbers of male participants in each exposure category. Such evaluations must be based on the statistical sensitivities of the specific tissue biomarkers and health endpoints for detecting changes. This article summarizes the components of the ideal field study and identifies research needs for improving field studies of male effects and for understanding the mechanisms of male reproductive toxicity. Several promising semen methods currently under development are also discussed.

Adult↗
PubMedDate not supplied

Biochemical markers of sperm function: male fertility and sperm selection for ICSI.

The expression of a 70 kDa chaperone protein, HspA2 (formerly called CK-M), has been identified in mature human spermatozoa. The central role of HspA2 has been established, as the expression level of this protein is related to sperm cellular maturity, DNA integrity, chromatin maturity, chromosomal aneuploidy frequency and sperm function, including fertilizing potential. The spermiogenetic events of cytoplasmic extrusion and remodelling of the plasma membrane, which facilitate the formation of zona pellucida binding site(s) in human spermatozoa, are related. Finally, the presence of the hyaluronic acid (HA) receptor on the plasma membrane of mature sperm coupled with the HA-coated slide sperm-binding assay, facilitates the testing of infertile men and the selection of single mature spermatozoa for ICSI. Because mature spermatozoa have no residual cytoplasm, the HA-bound sperm fraction is also enriched in spermatozoa that are normal by the Kruger strict morphology method.

Aneuploidy↗
PubMedDate not supplied

In vitro sperm-binding assay to distinguish differences in populations of human sperm or damage to sperm resulting from cryopreservation.

Annually, >1.3 million men are members of couples seeking help because of infertility. Semen from many of these men contains reasonable numbers of motile and normal sperm, but for a subset of individuals, many sperm are deficient in ability to bind to the zona pellucida during in vitro fertilization. Diagnosis of this defect has been hampered by lack of a low-cost test. Molecular similarity exists between the perivitelline membrane of a hen's egg and the mammalian zona pellucida. These facts and some preliminary data led to evaluation of binding of human sperm during incubation for 60 minutes at 37 degrees C to an extract of chicken perivitelline membrane coated in microwell assay plates. The sperm-binding assay had inter- and intraassay plate variations of 21 and 12%, respectively, using washed fresh sperm. All seminal samples were normal, except a few that had 36 to 50% motile sperm with a low rate of sperm movement (if there is a low rate of movement, World Health Organization [WHO] criterion for normalcy is >50% motile). Nevertheless, this sperm-binding assay detected differences among individuals in percentage of sperm bound. Based on data for two to four ejaculates from each of eight occasional sperm donors, the coefficient of variation for ejaculates within donor averaged 31%, and means for the donors differed (P < 0.02). Percentage of sperm bound ranged from <1 to 38% for fresh semen from 57 men and from <1 to 13% for frozen-thawed semen from 34 men. Percentage of motile sperm accounted for <30% of the variation in percentage of sperm bound. In a direct comparison based on 17 ejaculates, aliquots evaluated fresh averaged 13% sperm bound, versus 2% for frozen-thawed aliquots. We concluded that the egg membrane substrate used in these microwell assay plates might serve as the basis for a diagnostic assay. However, it remains to be established whether samples of human semen with a low percentage of sperm binding indeed have relatively low fertilizing potential.

Cell Adhesion↗
PubMedDate not supplied

Increased in vitro binding of fresh and frozen-thawed human sperm exposed to a synthetic peptide.

Prosaposin is a well-characterized, approximately 68-kDa protein found in many tissues and as a normal component of human semen. A fragment of prosaposin apparently is involved in primary sperm-egg binding. We hypothesized that binding of sperm from some men to egg investments would be increased by in vitro exposure of their sperm to a synthetic fragment of human prosaposin (FertPlus peptide). Hence, we evaluated samples of washed fresh or frozen-thawed human sperm after a 10-minute exposure to synthetic FertPlus peptide at 0 (control), 80, 160, 320, 640, or 1280 pM, followed by 1:50 dilution for evaluation of binding. The criterion of response was mean percentage of sperm bound to a substrate prepared from chicken egg membranes after sperm were incubated for 60 minutes at 37 degrees C in substrate-coated wells of a sperm-binding assay plate. For each seminal sample, data were normalized against the percentage of sperm bound for control aliquots, providing values for relative binding. With fresh sperm, relative binding was increased (P < 0.01) by exposure of sperm to peptide, and the effect was especially obvious at 1280 pM. Higher doses were not tested. Collectively at three study sites, exposure of fresh sperm to 1280 pM peptide substantially increased (above 99% confidence interval; on the basis of duplicate control samples) percentage of sperm bound for 25 of 74 (34%) samples. For frozen-thawed sperm, exposure to 1280 pM peptide increased binding for 29 of 65 (45%) samples. We concluded that for >30% of men, exposure of their sperm to this synthetic fragment of prosaposin at 1280 pM increased binding of sperm to an egg membrane substrate similar to that offered by the zona pellucida.

Amino Acid Sequence↗
PubMedDate not supplied

Adenosine triphosphate (ATP) concentrations and ATP/adenosine diphosphate ratios in human sperm of normospermic, oligospermic, and asthenospermic specimens and in their swim-up fractions: lack of correlation between ATP parameters and sperm creatine kinase concentrations.

The authors had previously found an inverse correlation between per sperm creatine phosphokinase activity and sperm concentrations in men. Because creatine phosphokinase is a key enzyme in sperm energy transport, the possible relationship of sperm creatine phosphokinase activity, sperm adenosine triphosphate (ATP) concentrations, sperm ATP/ADP (adenosine diphosphate) ratios, and computer-aided semen analysis sperm motility parameters were then studied. The ATP concentrations and ATP/ADP ratios, measured by high-pressure liquid chromatography in washed sperm, were similar in normospermic and oligospermic specimens (ATP: 123.1 +/- 21.6 vs. 90.0 +/- 24.5 pmol/10(6) sperm; ATP/ADP: 2.8 +/- 0.4 vs. 2.1 +/- 0.4, N = 32 and 17, mean +/- SEM), and in samples with normal and less than 40% sperm motility (ATP: 96.8 +/- 27.2 vs. 122.2 +/- 19.6 pmol/10(6) sperm; ATP/ADP: 2.4 +/- 0.5 vs. 2.8 +/- 0.4, n = 26 and 23). In the swim-up sperm fractions, which showed improved motility, the ATP concentrations, but not the ATP/ADP ratios, were lower than in the initial semen samples (ATP: 152.9 +/- 28.4 vs. 90.3 +/- 10.6 pmol/10(6) sperm, P less than 0.05; ATP/ADP: 3.3 +/- 0.5 vs. 3.9 +/- 0.7, N = 18 pairs of samples). This is consistent with our previous finding of a lower cytoplasmic content in sperm in swim-up fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate↗