Heritable anisotropy associated with cognitive impairments among patients with schizophrenia and their non-psychotic relatives in multiplex families

BACKGROUND

To test the functional implications of impaired white matter (WM) connectivity among patients with schizophrenia and their relatives, we examined the heritability of fractional anisotropy (FA) measured on diffusion tensor imaging data acquired in Pittsburgh and Philadelphia, and its association with cognitive performance in a unique sample of 175 multigenerational non-psychotic relatives of 23 multiplex schizophrenia families and 240 unrelated controls (total = 438).

METHODS

We examined polygenic inheritance (h2r) of FA in 24 WM tracts bilaterally, and also pleiotropy to test whether heritability of FA in multiple WM tracts is secondary to genetic correlation among tracts using the Sequential Oligogenic Linkage Analysis Routines. Partial correlation tests examined the correlation of FA with performance on eight cognitive domains on the Penn Computerized Neurocognitive Battery, controlling for age, sex, site and mother's education, followed by multiple comparison corrections.

RESULTS

Significant total additive genetic heritability of FA was observed in all three-categories of WM tracts (association, commissural and projection fibers), in total 33/48 tracts. There were significant genetic correlations in 40% of tracts. Diagnostic group main effects were observed only in tracts with significantly heritable FA. Correlation of FA with neurocognitive impairments was observed mainly in heritable tracts.

CONCLUSIONS

Our data show significant heritability of all three-types of tracts among relatives of schizophrenia. Significant heritability of FA of multiple tracts was not entirely due to genetic correlations among the tracts. Diagnostic group main effect and correlation with neurocognitive performance were mainly restricted to tracts with heritable FA suggesting shared genetic effects on these traits.

TNF-stimulated arginine transport by human vascular endothelium requires activation of protein kinase C

OBJECTIVE

The authors determined the endothelial arginine transport mechanism and the potential role of a tumor necrosis factor (TNF)-alpha-mediated signal transduction pathway involving protein kinase C (PKC) in regulating this transport in cultured endothelial cells.

SUMMARY BACKGROUND DATA

The vascular endothelium metabolizes arginine to generate nitric oxide (NO), and an increase in NO production can be stimulated by several cytokines. The mechanism(s) responsible for the accelerated arginine transport are poorly understood.

METHODS

Arginine transport was assayed in confluent human umbilical vein endothelial cells in the presence of TNF +/- the PKC inhibitor chelerythrine chloride.

RESULTS

Carrier-mediated arginine transport was accomplished by two Na(+)-independent transporters, System y+ (80% of total transport) and System b0,+ (20% of transport). Tumor necrosis factor (0.1-2 ng/mL) increased System y(+)-mediated arginine transport in a time- and dose-dependent manner by augmenting System y+ transport maximal capacity (control Vmax = 1325 +/- 60 pmol/mg protein/minute vs. TNF Vmax = 3015 +/- 110 pmol/mg protein/minute, p < 0.01) without affecting transporter affinity (control Km = 30 +/- 1.4 microM vs. 34 +/- 1.3 microM arginine, p = NS). Stimulation was maximal at the 8-hour time point and was inhibited by both actinomycin D and cycloheximide. In addition, inhibition of PKC with chelerythrine abrogated the TNF-augmented arginine transport. Similarly, incubation of cells with the direct PKC activator TPA (phorbol ester 12-myristate 13-acetate) stimulated System y(+)-mediated arginine transport nearly fivefold, secondary to an increase in transporter Vmax (TPA Vmax = 5349 +/- 310 pmol/mg protein/minute, p < 0.001 vs. control), with no change in Km. This TPA-induced stimulation of arginine transport also was blocked by chelerythrine CI, actinomycin D, and cycloheximide. Incubation of TNF-stimulated cells with two NO synthase inhibitors did not reduce transport activity, suggesting that the arginine transporter and the NO synthase enzyme may, in part, be independently regulated.

The management of vascular injuries of the extremity associated with civilian firearms

A penetrating extremity trauma registry was created to prospectively study the physical findings, use of arteriography, nonoperative management with embolization or observation and operation in the management of vascular injuries. During a recent ten month period, 228 patients with 320 injuries of the extremity secondary to firearms were admitted to the Trauma Service. Twenty-four percent of the patients had more than one injury, and there were six perioperative deaths related to associated injuries. Fifty-one patients had 50 arterial and 17 venous injuries. Limb salvage was 100 percent. Twenty-two patients with obvious arterial injuries were taken directly to the operating room without arteriography. Arteriography was performed immediately after admission in 41 patients and the findings were positive in 46.4 percent of the patients; nine required operation. Arteriography was performed for injuries in proximity to a major vessel as the indication in 153 injuries and revealed seven arterial injuries (4.6 percent). Three patients underwent operation. Five patients with arterial injuries had successful embolization during the initial arteriography and five patients with intimal injuries were observed, four healed and one patient was lost to follow-up evaluation. Operative repair of arterial injuries included the use of saphenous vein (21 patients), prosthetic grafts (seven patients) and ligations (four patients). Seventeen venous injuries were either repaired (eight patients) or ligated (nine patients). In the patients undergoing operative repairs, 68.7 percent had fasciotomies performed. The excellent results in the current study (no amputations with 51 survivors of arterial injuries) were obtained by a multidisciplinary approach, involving selective arteriography to avoid unnecessary operation and operative repair in those with extensive vascular injuries. The use of arteriography for proximity characterized a few vascular injuries requiring operation or observation. It should serve as the standard for evaluating noninvasive diagnostic studies and for studying the natural history of asymptomatic injuries.

Vascular complications associated with spontaneous aortic dissection

Three hundred twenty-five cases of spontaneous aortic dissection seen at two institutions between 1965 and 1986 were reviewed to assess the incidence, morbid sequelae, and specific management of aortic branch compromise. Noncardiac vascular complications occurred in 33% of the study group, and in these patients the overall mortality rate (51%) was significantly (p less than 0.001) higher than in patients without (29%) such complications. Although aortic rupture was the strongest correlate of mortality (90%), death specifically related to vascular occlusion was common when such occlusion occurred in the carotid, mesenteric, and renal circulation. There was a strong correlation between stroke and carotid occlusion (22/26 cases), yet specific carotid revascularization was only used during the chronic phase of the disease. Similarly, peripheral operation was ineffective in reducing the mortality rate in the setting of mesenteric (87%) and renal (50%) ischemia. Fifteen patients required either fenestration or graft replacement of the abdominal aorta for acute obstruction, rupture, or chronic aneurysm development. Thirty-eight patients (12%) demonstrated some degree of lower extremity ischemia, and one third of these required a direct approach on the abdominal aorta or iliofemoral segments to restore circulation. Selected patients with acute aortic dissection may require peripheral vascular operation in accordance with a treatment strategy that directs initial attention to the immediate life-threatening complications.