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51.
Joan Stiles Pamela Moses Katherine Roe Natacha A Akshoomoff Doris Trauner John Hesselink Eric C Wong Lawrence R Frank Richard B Buxton 《Journal of the International Neuropsychological Society》2003,9(4):604-622
The current study presents both longitudinal behavioral data and functional activation data documenting the effects of early focal brain injury on the development of spatial analytic processing in two children, one with prenatal left hemisphere (LH) injury and one with right hemisphere (RH) injury. A substantial body of evidence has shown that adults and children with early, lateralized brain injury show evidence of spatial analytic deficits. LH injury compromises the ability to encode the parts of a spatial pattern, while RH injury impairs pattern integration. The two children described in this report show patterns of deficit consistent with the site of their injury. In the current study, their longitudinal behavioral data spanning the age range from preschool to adolescence are presented in conjunction with data from a functional magnetic resonance imaging (fMRI) study of spatial processing. The activation results provide evidence that alternative profiles of neural organization can arise following early focal brain injury, and document where in the brain spatial functions are carried out when regions that normally mediate them are damaged. In addition, the coupling of the activation with the behavioral data allows us to go beyond the simple mapping of functional sites, to ask questions about how those sites may have come to mediate the spatial functions. 相似文献
52.
Harold M. Frost 《Journal of bone and mineral metabolism》1997,15(1):9-16
Inanimate structures cannot detect and repair their fatigue damage or microdamage, so to minimize it they need more structural
material and strength. Living bone handles this matter differently. Bone modeling drifts adapt bone architecture and strength
to the loads on bones in ways that tend to keep strains from exceeding a “modeling threshold” range. Strains (or equivalent
features) above that threshold switch mechanically controlled modeling ON. Where strains stay below that threshold, this modeling
goes OFF. Repeatedly loading-deloading a bone causes microdamage in it, and basic multicellular unit (BMU)-based bone remodeling
normally repairs it. Where strains stay below an operational “microdamage threshold,” remodeling can repair whatever microdamage
happens for as long as it happens. Strains above that threshold can cause too much microdamage to repair completely and lead
to fatigue fractures of trabeculae or whole bones. The modeling threshold normally lies comforably below the microdamage threshold.
Since modeling normally adjusts bone architecture to keep strains from exceeding the modeling threshold, this keeps strains
below the microdamage threshold, too, and voluntary activities do not cause more microdamage than remodeling can repair. Therefore,
long-distance runners do not need more bone mass and strength than nonrunners of comparable age, sex, and body size. 相似文献
53.
Steven M Kawut Darren B Taichman Vivek N Ahya Sandra Kaplan Christine L Archer-Chicko Stephen E Kimmel Harold I Palevsky 《Liver transplantation》2005,11(9):1107-1111
It is not known whether patients with pulmonary arterial hypertension associated with portal hypertension (portopulmonary hypertension (PPHTN) have different disease characteristics from those of patients with other forms of pulmonary arterial hypertension. We performed a retrospective cohort study of patients with PPHTN and patients with pulmonary arterial hypertension that was idiopathic, familial, or associated with anorexigen use (IPAH) to determine whether hemodynamics or survival were different between these groups. We included consecutive patients who underwent initial pulmonary artery catheterization and vasodilator testing at our center between January 1997 and May 2001 and who were followed until January 2004. Patients with PPHTN (N = 13) had a higher cardiac index and lower pulmonary vascular resistance than patients with IPAH (N = 33) (P < or = 0.001). Right atrial pressure and pulmonary artery pressure were similar between the groups. Patients with PPHTN had a higher risk of death in multivariate analysis (hazard ratio: [HR] = 2.8, 95% CI 1.04-7.4; P = 0.04). These findings were not affected by adjustment for differences in laboratory values, hemodynamics, or therapy. In conclusion, patients with PPHTN have a higher risk of death than that of patients with IPAH, despite having a higher cardiac index and lower pulmonary vascular resistance. Future studies of the specific mechanisms of and therapy for pulmonary arterial hypertension should focus on the distinctions between the different forms of this disease. 相似文献
54.
Nico J. D. Nagelkerke Stephen Moses Francis A. Plummer Robert C. Brunham David Fish 《Statistics in medicine》1995,14(8):769-775
In case-control studies, cases are sampled separately from controls. In such studies the primary analysis concerns the estimation of the effect of covariables on being a case or a control. To explore causal pathways, further secondary analysis could concern the relationships among the covariables. In this paper the validity of such secondary analysis is addressed. In particular, the use of multiple logistic regression in case-control studies where the dependent variable is not the case/control indicator is explored. It is shown that only under very restrictive conditions will sample regression coefficients correctly estimate their true value. In many situations, it may be valid to regress one covariable on others in the control group, but not in the case group or the combined sample. This principle is illustrated by a study of sexually transmitted disease in Kenya. 相似文献
55.
Harold B. Canning DDS David E. Frost DDS MS Daniel K. McDonald DDS Robert W. Joyner MD 《Journal of oral and maxillofacial surgery》1988,46(12):1048-1050
In a double-blind, randomized plan of drug administration, nalbuphine, fentanyl, and a placebo were compared for efficacy in sedation and analgesia during third molar removal. Fifty-eight patients participated in this study. Using accepted intravenous sedation and surgical techniques, fentanyl and nalbuphine were found to be better than placebo for anxiety and pain control in third molar surgery. Fentanyl had a longer duration of pain relief postoperatively than did nalbuphine. The study confirmed the need for a narcotic supplement to sedation techniques for third molar surgery. 相似文献
56.
Gallbladder dyskinesia in chronic acalculous cholecystitis 总被引:4,自引:0,他引:4
Dr. William R. Brugge MD Douglas L. Brand MD Harold L. Atkins MD Bernard P. Lane MD William G. Abel MD 《Digestive diseases and sciences》1986,31(5):461-467
To test the hypothesis that there is an early stage of cholesterol gallstone formation in man characterized by symptoms of chronic cholecystitis, poor gallbladder emptying, and biliary cholesterol crystals, we studied cholecystokinin-stimulated gallbladder emptying by DISIDA scintigraphy and examined bile for cholesterol crystals in symptomatic patients with normal oral cholecystography and gallbladder sonography. Of 36 patients studied, 16 had biliary cholesterol crystals; their mean 30-min gallbladder ejection fraction was 25.9±14.8%. Among the 20 patients without crystals, the mean ejection fraction was 60.3±23.3%. Fifteen patients, 11 with crystals and four without, had cholecystectomy because of persistent symptoms. All with crystals preoperatively and three without had chronic cholecystitis histologically. One patient without crystals had normal histology. We conclude that poor gallbladder contractility, well-established as an etiologic factor in animal models of cholesterol cholelithiasis, is now linked to acalculous cholecystitis, an early stage of human cholesterol cholelithiasis. 相似文献
57.
Hematological Complications of Alcoholism 总被引:4,自引:0,他引:4
Harold S. Ballard 《Alcoholism, clinical and experimental research》1989,13(5):706-720
Numerous clinical observations support the notion that ethanol has multiple pathologic effects on hematopoietic tissue. The effects of alcohol on blood are diverse. The long-term ingestion of large quantities of ethanol has been shown to alter a substantial number of physiologic and biochemical variables. Abnormalities involving leukocytes, platelets, and erythrocytes may occur singly or in various combinations. Due to the frequent concomitant presence of alcohol-related hepatic disease, nutritional deficiencies, infection, and other chronic diseases, it is often difficult to distinguish the specific hematologic toxicities of alcohol ingestion from the hematologic toxicities of associated morbid conditions. Depressed hematopoietic cell formation (Table 2), increased destruction, and alterations in morphology and function of hematopoietic cells have been described. 相似文献
58.
59.
60.
Coexistence of Neoplasia and Cortical Dysplasia in Patients Presenting with Seizures 总被引:16,自引:10,他引:6
Summary: Tumors and cortical dysplasia are associated with epilepsy, but few studies have examined the coexistence of neoplasia and dysplasia in these patients. We studied 13 patients (age 4–29 years) with recurrent seizures of 1 month to 21-year' duration (median 72 months). Ten patients were aged <21 years. Imaging studies localized the lesion to the temporal lobe (10 patients), parietal lobe (2 patients), and frontal lobe (1 patient). Tumors included ganglioglioma (8 patients), dysembryoplastic neuroepithelial tumor (DNT) (3 patients), and low-grade as- trocytoma (2 patients). Cortical dysplasia, including atypical aggregates of neurons (6 patients), multifocal loss of the cortical laminar architecture (7 patients), and neurons in the molecular layer of the cortex (3 patients) were observed near but separate from the tumor. Coexistence of certain tumors with cortical dysplasia, most frequently observed in the pediatric population, suggests a hamar-tomatous/dysplastic nature of the neoplasms. 相似文献