Flanking markers define the X-linked hypophosphatemic rickets gene locus.

X-linked hypophosphatemic rickets (HYP) is an X-linked dominant disorder characterized by decreased renal tubular phosphate reabsorption and consequent hypophosphatemia. The defect in tubular phosphate reabsorption is probably secondary to an unidentified humoral factor. Identification of the humoral factor and a full understanding of the pathophysiology of the disease await the identification of the HYP gene. Previously we demonstrated that DXS257 and DXS41 are flanking markers for the HYP gene. Two markers, DXS365 and DXS274, are tightly linked to the HYP gene, but investigators have been unable to determine whether they are centromeric or telomeric to the disease gene. Since tightly linked flanking markers are necessary prerequisites to obtain the gene by positional cloning techniques, we sought to determine the relative positions of these markers to the HYP gene by expanding our data base for linkage studies. We also investigated a new polymorphic probe for linkage to HYP to construct a more detailed genetic map around the HYP locus. Our data indicate that the markers DXS365, DXS274, and DXS92 are tightly linked to the HYP locus and suggest a locus order of Xtel-(DXS444/DXS315)-DXS43-(DXS257/DXS3 65)-HYP-(DXS274/DXS41/DXS92)-DXS-451- DXS319-Xeen. These results will facilitate attempts further to localize and clone the HYP gene.

The interaction of diltiazem with lovastatin and pravastatin.

BACKGROUND: Lovastatin is oxidized by cytochrome P4503A to active metabolites but pravastatin is active alone and is not metabolized by cytochrome P450. Diltiazem, a substrate and a potent inhibitor of cytochrome P4503A enzymes, is commonly coadministered with cholesterol-lowering agents. METHODS: This was a balanced, randomized, open-label, 4-way crossover study in 10 healthy volunteers, with a 2-week washout period between the phases. Study arms were (1) administration of a single dose of 20 mg lovastatin, (2) administration of a single dose of 20 mg pravastatin, (3) administration of a single dose of lovastatin after administration of 120 mg diltiazem twice a day for 2 weeks, and (4) administration of a single dose of pravastatin after administration of 120 mg diltiazem twice a day for 2 weeks. RESULTS: Diltiazem significantly (P < .05) increased the oral area under the serum concentration-time curve (AUC) of lovastatin from 3607 +/- 1525 ng/ml/min (mean +/- SD) to 12886 +/- 6558 ng/ml/min and maximum serum concentration (Cmax) from 6 +/- 2 to 26 +/- 9 ng/ml but did not influence the elimination half-life. Diltiazem did not affect the oral AUC, Cmax, or half-life of pravastatin. The average steady-state serum concentrations of diltiazem were not significantly different between the lovastatin (130 +/- 58 ng/ml) and pravastatin (110 +/- 30 ng/ml) study arms. CONCLUSION: Diltiazem greatly increased the plasma concentration of lovastatin, but the magnitude of this effect was much greater than that predicted by the systemic serum concentration, suggesting that this interaction is a first-pass rather than a systemic event. The magnitude of this effect and the frequency of coadministration suggest that caution is necessary when administering diltiazem and lovastatin together. Further studies should explore whether this interaction abrogates the efficacy of lovastatin or enhances toxicity and whether it occurs with other cytochrome P4503A4-metabolized 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, such as simvastatin, fluvastatin, and atorvastatin.

Degree of pathology as related to readiness to accept labels in process and reactive schizophrenics.

Two experiments were performed in order to determine whether readiness to accept deviant labels, as measured by acquiescence set, interacts with type of schizophrenia (process vs. reactive) to influence level of pathology. It was found on both a behavioral measure and a psychometric measure of psychopathology that high acquiescent process schizophrenics manifested more pathology than did either low acquiescent process or reactive schizophrenics, both of whom showed more pathology than high acquiescent reactive schizophrenics. The results suggest that one's acceptance of deviant labels as well as one's past history of being assigned social and evaluative labels may influence the patient's level of pathology. Scheff (1966), in viewing the mental patient from a sociological perspective, suggests that an important determinant of mental disorder is the acceptance by the deviant individual of the various labels which stigmatize him as mentally ill. If this is the case, then individual differences in readiness to accept or agree with labels about oneself may be related to the degree of pathology manifested in a psychiatric population. The present authors sought to determine if acquiescence set, as measured by the Agreement Response Scale (Couch & Keniston, 1960), is related to degree of pathology in schizophrenic patients. The Agreement Response Scale was used as a measure of the general tendency to acquiesce to or agree with personality statements or labels. The investigators performed two experiments, in Experiment 1 a behavioral measure of pathology was used and in Experiment 2 a psychometric measure of pathology was used. In addition, the schizophrenic Ss were grouped according to the process-reactive distinction as the reactive schizophrenic may be expected to have a more favorable history of labeling than would the process schizophrenic.

Multicenter experience with perventricular device closure of muscular ventricular septal defects.

Hybrid procedures are becoming increasingly important, especially in the management of congenital heart lesions for which there are no ideal surgical or interventional options. This report describes a multicenter experience with perventricular muscular venticular septal defect (VSD) device closure. Three groups of patients (n = 12) were identified: infants with isolated muscular VSDs (n = 2), neonates with aortic coarctation and muscular VSDs (n = 3) or patients with muscular VSDs and other complex cardiac lesions (n = 2), and patients with muscular VSDs and pulmonary artery bands (n = 5). Via a sternotomy or a subxyphoid approach, the right ventricle (RV) free wall was punctured under transesophageal echocardiography guidance. A guidewire was introduced across the largest defect. A short delivery sheath was positioned in the left ventricle cavity. An Amplatzer muscular VSD occluding device was deployed across the VSD. Cardiopulmonary bypass was needed only for repair of concomitant lesions, such as double-outlet right ventricle, aortic coarctation, or pulmonary artery band removal. No complications were encountered using this technique. Discharge echocardiograms showed either mild or no significant shunting across the ventricular septum. At a median follow-up of 12 months, all patients were asymptomatic and 2 patients had mild residual ventricular level shunts. Perventricular closure of muscular VSDs is safe and effective for a variety of patients with muscular VSDs.