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Biomedical subjects

J Cervenka

Publications and source records attributed to J Cervenka.

At least 55 records · Page 3Linked to original sources
PubMed1984

Ring chromosome 14 and immunoglobulin locus.

A 2.5-yr-old girl was evaluated for seizurelike episodes and psychomotor and growth retardation. Cytogenetic study showed a ring 14 chromosome in most cells, with some cells having monosomy 14. Rarely, a cell showed a double ring chromosome 14. Both parents had normal chromosomes. Because serum immunoglobulins have been mapped to the distal portion of 14q, we attempted to correlate Ig levels with the deletion involved in the formation of this ring. No decrease in IgG, IgM, IgA, IgE, and IgD serum levels was observed. The normal serum Ig levels found in the proposita are compatible with the suggestion that the Ig loci are not located on the terminal portion of 14q but more proximally in band 14q32. However, because Gm and Am allotyping was not available mapping was not conclusive.

Child, Preschool↗
PubMed1984

DNA replication and inactivation patterns in structural abnormality of sex chromosomes. I.X-A translocations, rings, fragments, isochromosomes, and pseudo-isodicentrics.

High resolution chromosome analysis and bromodeoxyuridine (BrdUrd) incorporation have been applied to study patterns of chromosomal replication (inactivation) in two cases of unbalanced X-autosome translocations, seven cases of X and Y chromosome rings or fragments, and five cases of dicentric isochromosomes (Xq). Our results indicate the following: (1) In (X-A) translocations, detailed replicational analysis of the translocated autosomal segment is informative. Absence of "spreading effect" and partial-incomplete spreading effect are the most common observations. (2) Sex chromosome derived fragments and rings can be differentiated based on their replicational features. (3) Dicentric isochromosomes (Xq) can be classified based on intercentromeric distances, replicational asynchrony, and centromere inactivation. (4) A correlation between intercentromeric distance and degree of 45,X mosaicism was observed in dicentric "i(Xq)" chromosomes. Evidence for spreading effect based on our results and on the review of the literature has been critically analyzed and general rules in evaluating spreading effects (SE) proposed. The cytologic detection of active regions on the late replicating X chromosome and the inactivation capacity of the juxtacentromeric region of Xp is evaluated. It is proposed that centromere suppression and underreplication are related phenomena. Finally, the analysis of informative replicational stages is emphasized and the application of their analysis in basic and clinical cytogenetics demonstrated.

Adolescent↗
PubMed1984

Characterization of the distribution of sister chromatid exchange frequencies: implications for research design.

Mitoses from 21 individuals were examined to characterize the within and between subjects distributions of sister chromatid exchange (SCE) frequencies. The importance of accounting for both the within subjects and between subjects variability in the design and interpretation of research is demonstrated. A computer simulation study was performed to evaluate the estimate of an individual's mean SCE rate. A power analysis was performed using our transformed descriptive data to determine the percentage difference in SCE which could be detected between two groups (with 95% probability) as a function of both the number of mitoses per individual and the number of individuals in each group. Tables are provided as guidelines. Conclusions from our work include: (1) The empirical distribution of SCEs within an individual is best described by a negative binomial distribution; (2) The predominant source of variability in baseline SCE rates is between cells within a given individual rather than between individuals and can be accounted for in experiments by counting adequate numbers of mitoses per individual; and (3) There is a systematic relationship between the mean and SD for SCEs which should be removed prior to hypothesis testing by taking either a logarithmic transformation or square root transformation of the data.

Analysis of Variance↗
PubMed1984

Comparative effects of antihypertensive therapy with guanabenz and propranolol on renal vascular resistance and left ventricular mass.

There is increasing interest in initial therapy of hypertension with sympatholytic agents and the influence of antihypertensive therapy on cardiac and renal function. We treated 26 men with essential hypertension with either guanabenz alone (n = 14) or propranolol alone (n = 12) and assessed blood pressure and renal perfusion before and after 5-7 weeks of treatment. Cardiac performance was evaluated for the guanabenz-treated patients. Both drugs substantially reduced blood pressure without weight gain. During guanabenz therapy, glomerular filtration rate and renal blood flow were preserved, with a fall in renal vascular resistance (from 12,100 +/- 1,500 to 9,300 +/- 1,190 dyne X s X cm-5, p less than 0.01). Propranolol decreased glomerular filtration rate (from 95 +/- 11 to 70 +/- 6 ml/min, p less than 0.05) without significant change in renal blood flow or renal vascular resistance. In guanabenz-treated patients, there was a decline in left ventricular mass (from 290 +/- 23 to 257 +/- 14 g, p = 0.067). Thus, both agents are effective initial therapy in hypertension. Guanabenz treatment also was associated with reduced renal vascular resistance and left ventricular mass.

Adult↗
PubMed1984

Contrasting renal haemodynamic responses to the angiotensin converting enzyme inhibitor enalapril and the beta-adrenergic antagonist metoprolol in essential hypertension.

The individual target organ response to blood pressure reduction is an important criterion in the selection of appropriate antihypertensive therapy. We assessed both the renal and the systemic haemodynamic responses to antihypertensive monotherapy (five to seven weeks) with the angiotensin converting enzyme (ACE) inhibitor enalapril (n = 12), in contrast to the cardioselective beta-adrenergic blocker metoprolol (n = 11) in subjects with essential hypertension. Enalapril lowered systolic and diastolic blood pressure, and the fall in blood pressure was mediated haemodynamically by a 34% fall in systemic vascular resistance. In the kidney, glomerular filtration rate, renal plasma flow and renal blood flow were maintained by a 23% fall in renal vascular resistance. The disproportionate fall in systemic resistance versus renal resistance actually reduced the renal fraction of cardiac output. By contrast, metoprolol lowered predominantly diastolic blood pressure, with an associated 25% fall in cardiac output, without significant changes in overall systemic vascular resistance. In the renal circulation, renal perfusion was well maintained by a 20% fall in renal vascular resistance, perhaps at the efferent arteriole, without change in the renal fraction of cardiac output. Neither drug altered weight, plasma volume or total blood volume. Thus, each drug represents effective antihypertensive monotherapy, with a generally favourable, though different, renal haemodynamic profile, characterized by effective autoregulation of renal perfusion even in the face of a fall in perfusion pressure.

Adult↗
PubMed1984

African mask with cleft lip and palate.

An African mask depicting cleft lip and palate is described. This artifact has been used for entertainment by Fon tribe of Dohomey (Benin) in West Africa. The function and style of the mask is discussed.

Benin↗
PubMed1983

Cytogenetic differentiation of Fanconi anemia, "idiopathic" aplastic anemia, and Fanconi anemia heterozygotes.

We have analyzed chromosome breaks in 8 patients with Fanconi anemia (FA), 42 with "idiopathic" aplastic anema (AA), 15 first-degree relatives of FA patients, and 13 controls. Their lymphocytes were treated in culture with three concentrations of mitomycin-C (MMC). A 60-fold increase in breaks was observed in FA patients as compared to AA patients, regardless of severity of clinical signs. The MMC-stress test was standardized to clearly differentiate FA from other pancytopenias in doubtful cases. Also, the effect of storage of MMC in solution was investigated. The data on SCEs of 12 subjects tested, 10 mo apart, showed an inverse relationship between length of storage of MMC and chromosome damage. The 10-month-old solution induced only one half as many SCEs as it induced at 4 months. Further, the usefulness and power of diepoxybutane (DEB) in detection of FA heterozygotes was investigated in 12 first-degree relatives of patients with Fanconi anemia and 12 healthy controls. The mean number of chromosome breaks per mitosis by DEB stress in obligate heterozygotes was 0.08 in comparison to 0.06 in controls. Four of twelve control subjects showed proportions of breaks almost identical to or higher than those of FA heterozygotes, ie, 0.12, 0.10, 0.10, and 0.11 breaks per mitosis. The responses of healthy controls to DEB could be separated into two groups: one with mean chromosome breaks of 0.11 per mitosis, and a second with mean breaks of 0.04 per mitosis. Thus, it appears that heterozygote detection by DEB stress of cultured lymphocytes is not unequivocal.

Adolescent↗
PubMed1982

A role for 2,4-enoyl-CoA reductase in mitochondrial beta-oxidation of polyunsaturated fatty acids. Effects of treatment with clofibrate on oxidation of polyunsaturated acylcarnitines by isolated rat liver mitochondria.

1. beta-Oxidation of gamma-linolenoylcarnitine, arachidonoylcarnitine and docosahexaenoylcarnitine by isolated rat liver mitochondria is inhibited by uncoupling conditions. Partial re-activation is obtained with added ATP. With mitochondria from clofibrate-treated rats ATP-stimulated rates of beta-oxidation of docosahexaenoylcarnitine are higher than ADP-stimulated rates. This is not observed with the beta-oxidation of oleoylcarnitine. 2. beta-Oxidation of docosahexaenoylcarnitine, in the presence of rotenone, is inhibited by added oxaloacetate, analogous to previous findings with pent-4-enoylcarnitine [see Osmundsen (1978) FEBS Lett. 88, 219-222]. In the absence of rotenone added oxaloacetate stimulates the beta-oxidation of docosahexaenoylcarnitine, but has the opposite effect on the beta-oxidation of palmitoylcarnitine. 3. beta-Oxidation of polyunsaturated acylcarnitines by isolated rat liver mitochondria is selectively increased after treatment of the animals with a low dietary dose (0.2%, w/w) of clofibrate. Treatment with a higher dose of clofibrate (0.5%, w/w) resulted in a general stimulation of beta-oxidation. 4. The results presented suggest that long-chain fatty acids possessing a delta 4-double bond are not readily beta-oxidized unless the 2,4-enoyl-CoA reductase (EC 1.3.1.-) is operating.

2,4-Dinitrophenol↗
PubMed1982

Retinoblastoma and its association with a deletion in chromosome #13: a survey using high-resolution chromosome techniques.

To our knowledge, 20 cases of retinoblastoma associated with a chromosome #13 aberration have been reported. The present study utilized high-resolution prophase banding analysis of 12 additional retinoblastoma patients to determine the occurrence of chromosome aberrations and identify consistently associated clinical abnormalities. Six male and six female patients were studied representing seven cases of bilateral and five cases of unilateral retinoblastoma. One case of unilateral and two cases of bilateral retinoblastoma and detectable cytogenetic abnormalities, all involving an interstitial deletion of 13q14 on the long arm of one chromosome #13. In all five unilateral cases the tumor manifested in the left orbit, and in all seven bilateral cases the left eye was at a more malignantly advanced stage than the right eye. All three cases with a chromosome abnormality had varying degrees of developmental and/or mental retardation, along with at least one other congenital abnormality. In addition to the 12 cases of retinoblastoma, a patient with severe ophthalmologic abnormalities and mild congenital anomalies was studied by the prophase banding technique and found to be partially trisomic for the 13q14 region with gene loci for optic development and indicate that cytogenetic abnormalities may occur even more frequently in retinoblastoma than indicated by the small number of cases reported in the literature.

Child, Preschool↗
PubMed1982

Central and peripheral influences on retention of postural asymmetry in rats.

Four studies were conducted to delineate potential neural processes involved in retention of a peripherally induced postural asymmetry. In the first experiment, dorsal and ventral spinal root section following varying intervals of stimulation successfully abolished peripherally induced hindlimb asymmetry. Experiment 2 revealed that 50 min of ventral root stimulation, in the absence of central connection, was not effective in producing asymmetry persistence. In an attempt to more closely delineate the time parameters involved in peripherally induced asymmetry retention, Experiment 3 was conducted. Asymmetry was found to consistently outlast a spinal transection if 40 min of stimulation was given. Finally, possible modulatory higher brain center influences on the retention processes were demonstrated in Experiment 4. Asymmetry persistence was consistently observed in animals that received 10, 20, 30, 40, or 50 min of hindlimb stimulation if 50 min were allowed to elapse between the onset of stimulation and spinal section. These results, when coupled with the findings of earlier studies, suggest an active involvement of spinal reflex centers in the fixation process. In addition, these studies indicate that the manner in which reflex activity is altered is not crucial as long as underlying time parameters are adhered to. Finally, the present studies demonstrate that higher center influences can modulate retention of a postural asymmetry in a complex manner.

Animals↗