Peter V. Tishler

The familial aggregation of obstructive sleep apnea

An inherited basis for sleep-disordered breathing (SDB) has been suggested by reports of families with multiple affected members and by a previous study of the familial aggregation of symptoms of SDB. In this study, we quantify and characterize the aggregation of SDB and assess the degree to which familial similarities may be independent of obesity. This was a genetic-epidemiologic study that assessed the distribution of SDB in families identified through a proband with diagnosed sleep apnea and among families in the same community with no relative with known sleep apnea. SDB was assessed with overnight in-home monitoring of airflow, oxygen saturation, chest wall impedance, heart rate, and body movement. Standardized questionnaires were used to assess symptoms, and weight, height, and neck circumference were measured directly. Intergenerational and intragenerational correlation coefficients and pairwise odds ratios (ORs) were calculated with adjustment for proband sampling. In toto, 561 members of 91 families were studied: (1) 47 subjects with laboratory-confirmed SDB (index probands), (2) 44 community control subjects, and (3) the spouses and relatives of 1 and 2. Of all 91 families, 32 (35%) had two or more members with SDB, 30 (33%) had one affected member, and 29 had no affected members. SDB was more prevalent in the relatives of index probands (21%) than among neighborhood control subjects (12%) (p = 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

A convenient method of preparing polyacrylamide gels for liquid scintillation spectrometry.

Abstract A convenient method is described for the preparation for liquid scintillation spectrometry of slices of polyacrylamide gel containing isotopically labeled protein. Slices in counting vials are incubated with hydrogen peroxide (0.1 ml) at 50°. Complete solubilization of the gels occurs in several hours, and the aqueous material is combined with toluene-based scintillation fluid by the addition of NCS (1.0 ml). Efficiencies of counting are extremely high, and recoveries of radioisotope usually exceed 90%.

A Whole-Genome Scan for Obstructive Sleep Apnea and Obesity

Obstructive sleep apnea (OSA) is a common, chronic, complex disease associated with serious cardiovascular and neuropsychological sequelae and with substantial social and economic costs. Along with male gender, obesity is the most characteristic feature of OSA in adults. To identify susceptibility loci for OSA, we undertook a 9-cM genome scan in 66 white pedigrees (n=349 subjects) ascertained on the basis of either an affected individual with laboratory-confirmed OSA or a proband who was a neighborhood control individual. Multipoint variance-component linkage analysis was performed for the OSA-associated quantitative phenotypes apnea-hypopnea index (AHI) and body mass index (BMI). Candidate regions on chromosomes 1p (LOD score 1.39), 2p (LOD score 1.64), 12p (LOD score 1.43), and 19p (LOD score 1.40) gave the most evidence for linkage to AHI. BMI was also linked to multiple regions, most significantly to markers on chromosomes 2p (LOD score 3.08), 7p (LOD score 2.53), and 12p (LOD score 3.41). Extended modeling indicated that the evidence for linkage to AHI was effectively removed after adjustment for BMI, with the exception of the candidate regions on chromosomes 2p (adjusted LOD score 1.33) and 19p (adjusted LOD score 1.45). After adjustment for AHI, the primary linkages to BMI remained suggestive but were roughly halved. Our results suggest that there are both shared and unshared genetic factors underlying susceptibility to OSA and obesity and that the interrelationship of OSA and obesity in white individuals may be partially explained by a common causal pathway involving one or more genes regulating both AHI and BMI levels.

Polymorphism of the human Y chromosome: Fluorescence microscopic studies on the sites of morphologic variation

Normalized measurements were derived from quinacrine mustard stained normal‐ and variant‐size (large and small) human Y chromosomes. These measurements were used to study three problems:

A family with coexistent von Recklinghausen's neurofibromatosis and von Hippel‐Lindau's disease Diseases possibly derived from a common gene

A large kindred has two coexistent neurocutaneous syndromes: Certain members appear to have von Recklinghausens neurofibromatosis (cutaneous neurofibromata, café-au-lait spots), others have von Hippel-Lindaus disease (angiomatosis retinae, renal cell carcinomas, pancreatic cysts), and at least one individual has a combined syndrome (neurofibromata, café-au-lait spots, pheochromocytomas, cerebellar hemangioblastoma, renal cell carcinoma, pancreatic cysts). Inheritance may be through either two separate genes segregating coincidentally in this family, or a unique single gene with pleiotropic expressivity.

Dermatoglyphics in mosaic Down's syndrome.

To determine whether quantitative dermal indices are useful in ascertaining the liability for or severity of mosaic Downs syndrome (DS), dermatoglyphics of 107 subjects with proven 46/47,+ 21 DS were scored by four quantitative dermal indices. The distribution of mosaics by weighted mean percentage of +21 cells ranged from 1 to 95 and was bimodal. Mean maternal age at birth of mosaics (32.9 ± 7.5 years) was elevated when compared with control maternal ages in the literature.

FLUORESCENT IDENTIFICATION OF Y AND X CHROMATIN BODIES IN HUMAN TISSUES

Quinacrine mustard interphase fluorescence may be exploited to study Y and X chromosomal ploidy of many human tissues. Acetic alcohol-fixed cryostat tissue sections are superior, but formalin-fixed sections may also be used after the formalin is removed by vigorous washing in water. The percentage of cells of presumptively euploid female tissues which exhibit Y-like bodies is low, with means of less than l0% of all tissues except brain. In contrast, the mean percentages for euploid male tissues range between 50 and 63% (except for heart) and 30 and 40% when fixed in acetic alcohol and formalin, respectively. The differences between male and female tissues with either method of fixation were statistically significant. Nuclei with two fluorescent bodies were rare. The Barr body could also be recognized in all female tissues, and its presence could be quantitated in nuclei of skeletal and smooth muscle. This method permits the prospective and retrospective assessment of sex chromosomal ploidy, and the correlation of localized tissue karyotype with tissue function in individuals mosaic for aneuploidy of the Y.

Linkage of serum leptin levels in families with sleep apnea

OBJECTIVE:To identify regions on the genome linked to plasma leptin levels.DESIGN:Full genome scan with 402 microsatellite markers, spaced ∼10 cM apart. Data were analyzed using the Haseman–Elston regression linkage analysis.SUBJECTS:A total of 160 sibling pairs from 59 predominantly African American, obese families recruited to participate in a genetic-epidemiological study of obstructive sleep apnea.MEASUREMENTS:Serum leptin levels adjusted for age, sex, race and body mass index (BMI).RESULTS:Suggestive linkage peaks were observed on chromosomes 2 (P=0.00170; marker D2S1384), 3 (P=0.00007; marker D3S3034), 4 (P=0.00020; marker D4S1652) and 21 (P=0.00053; marker D21s1411).CONCLUSION:The peak on chromosome 3 is near the gene for glycogensynthase kinase 2 beta, an important factor in glucose homeostasis. Linkage was generally stronger after BMI adjustment, suggesting the potential influence of a number of metabolic pathways on leptin levels other than those that directly determine obesity levels. The evidence of linkage for leptin levels is consistent with prior linkage analyses for cholesterol, hypertension and other metabolic phenotypes.

Genetic and environmental control of blood pressure in twins and their family members.

An interdisciplinary study, in adult twins and their family members, of the genetic and environmental determinants of complex physiologic functions is in progress. This report summarizes our initial studies of the control of the level of systolic (K1) and diastolic (K5) blood pressure in 202 monogygotic (MZ) and 121 dizygotic (DZ) twins, their spouses and their children. Correlation coefficients for blood pressure were adjusted for the covariates age, sex, body mass index (wt/ht2) and screener, all of which significantly augment most correlations. These adjusted correlation coefficients in MZ twins are 0.5 for both K1 and K5 blood pressure. For DZ twins, the adjusted correlation coefficients are 0.21 (K1) and 0.24 (K5). MZ twin-offspring adjusted correlation coefficients are higher than MZ twin-niece/nephew adjusted correlation coefficients (0.12 and 0.06, respectively, for K1; 0.20 and 0.13, respectively, for K5), despite the genetic identity of these relationships. That environmental factors may explain these differences is suggested by other differences in adjusted correlation coefficients that are greater than those predicted by the degree of genetic similarity. In addition, we have assessed the relationship between two biochemical-physiological processes, the urinary excretion of kallikrein and transport of sodium in the erythrocyte (the sodium countertransport and the sodium-potassium-chloride cotransport systems), and blood pressure control, since both have been implicated in the control of blood pressure level. Although we found evidence for substantial genetic control of both phenomena, we were unable to establish any correlation between either function and the level of blood pressure in our normotensive subjects. These data point to the operation of three broad categories of control of level of blood pressure: constitutional factors (age, sex, body mass), genetic factors and environmental factors. The identities of the genetic and environmental factors are unknown at this time.

Studies on the location of the Y fluorescent body in human interphase nuclei.

SummaryThe present study assessed the intranuclear location of the Y chromosome, particularly to determine its relationship to the nuclear membrane. The quinacrine mustard fluorescence technique was used to identify the interphase Y body in nuclei of 5 types of cell (mononuclear, bilobulated nuclear and polymophonuclear leukocytes; buccal mucosal cells; and cultured skin fibroblasts) from 3 different populations of subjects (normal adults, normal neonates and XYY individuals). The location of the Y body was designated either peripheral (appearing to abut the nuclear membrane) or central. In nuclei with one Y fluorescent body, the mean percentages of apparent peripheral Y bodies decreased by the order polymorphonuclear leukocyte (90–96%), bilobulated nuclear leukocyte, mononuclear leukocyte, buccal cell, and fibroblast (6–11%). Most of these tissue-related differences were of high statistical significance in all of the subject groups. Mean nuclear diameters were also determined. The order of increasing size among the 5 types of nuclei was the same as the order of decreasing percentage of apparent peripheral Y bodies. This relationship might be expected even if the Y body is actually always contiguous with the nuclear membrane, since the central Y bodies may in fact be adjacent to the membrane in a plane that cannot be appreciated microscopically. This hypothesis was tested by means of a geometric model which accounts for the fact that although all Y bodies may actually be related to the nuclear membrane, only certain Y bodies will appear peripheral. The expected percentages of apparent peripheral Y bodies were derived for the various cell types by means of the model, and these were contrasted statistically with maximum likelihood estimates of the observed percentages. All differences were of high statistical significance P<0.001), rejecting the null hypothesis. The present study thus provides no evidence that the fluorescent portion of the Y chromosome is invariably associated with the nuclear membrane in interphase. Although there is evidence from a number of sources, including this laboratory, that the interphase Y may associate with the nucleolus, this evidence cannot at present be considered conclusive.ZusammenfassungDie vorliegende Studie befaßt sich mit der Lokalisation des Y-Chromosoms im Zellkern, besonders in ihrer Beziehung zur Kernmenbran. Die Quinacrine-Mustard-Fluorescenstechnik wurde dazu verwendet, das Y-Körperchen während der Interphase in Kernen von 5 verschiedene Zelltypen zu identifizieren (mononucleäre Zellen, Zellen mit Aufteilung des Kernes in zwei Läppchen sowie polymorphkernige Leukocyten; Mundschleimhaut-Zellen; kultivierte Fibroblasten. Es wurden 3 verschiedene Gruppen von Menschen untersucht: normale Erwachsene, normale Neugeborene und XYY-Individuen). Die Lokalisation des Y-Körperchens wurde entweder als peripher (an der Kernmembran) oder als zentral bezeichnet. In Kernen mit einem Y-Körperchen nahm der durchschnittliche Prozentsatz scheinbar peripherer Y-Körperchen in der folgenden Reihenfolgeab: polymorphkerniger Leukocyt (90–96%), Leukocyt mit zweigelapptem Kern, mononucleärer Leukocyt, Mundschleimhaut-Zelle und Fibroblast (6–11%). Die meisten dieser gewebespezifischen Unterschiede waren bei allen Patientengruppen statistisch signifikant. Außerdem wurden mittlere Kerndurchmesser bestimmt. Die Reihenfolge der ansteigenden Durchmesser war die gleiche wie die Reihenfolge des abnehmenden Prozentsatzes peripherer Y-Körperchen. Diese Beziehung ist zu erwarten, wenn das Y-Körperchen tatsächlich immer mit der Kernmembran verbunden ist, die Zellen aber in verschiedenen Ebenen betrachtet werden. Diese Hypothese wurde mit Hilfe eines geometrischen Modelles überprüft, indem die theoretisch ermittelten Werte mit den empirischen Daten verglichen wurden. Alle Unterschiede waren statistisch signifikant, was zur Verwerfung dieser Hypothese führte. So gibt diese Studie keine positiven Hinweise auf das Zutreffen der Hypothese, daß der fluorescierende Teil des Y-Chromosoms immer mit der Zellmembran verbunden ist. Es gibt andersartige Hinweise — auch aus dem Laboratorium der Autoren —, daß das Y-Körperchen mit dem Nucleus verbunden sein könnte; jedoch ist ein endgültiger Schluß noch nicht möglich.