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Biomedical subjects

J K Willis

Publications and source records attributed to J K Willis.

10 recordsLinked to original sources
PubMed1998

Hemophilia growth and development study: relationships between neuropsychological, neurological, and MRI findings at baseline.

OBJECTIVE: To determine the effects of human immunodeficiency virus (HIV) infection on children's development by identifying neurological and environmental variables associated with neuropsychological measures of cognitive development in HIV-seronegative (HIV-) and HIV-seropositive (HIV+)children and adolescents with hemophilia. METHODS: Participants (N = 298; 60% HIV+) were males ages 7-19 years enrolled in the Hemophilia Growth and Development Study (HGDS). Least squares modeling was used to determine whether there was a difference at baseline in mean neuropsychological test scores by HIV status, age, and neurological baseline findings, adjusting for selected environmental and medical history variables. RESULTS: The participants were within age expectations for general intelligence. Variables associated with lowered neuropsychological performance included academic problems, coordination and/or gait abnormalities, parents' education, and previous head trauma. CONCLUSIONS: Hemophilia-related morbidity has a subtle adverse influence on cognitive performance. HIV infection was not associated with neuropsychological dysfunction in this group even when MRI abnormalities were present.

Adolescent↗
PubMed1997

Longitudinal neurological follow-up of a group of HIV-seropositive and HIV-seronegative hemophiliacs: results from the hemophilia growth and development study.

BACKGROUND: Boys and young men with hemophilia treated with factor infusions before 1985 had a substantial risk of acquiring the human immunodeficiency virus (HIV) and the acquired immunodeficiency syndrome. This study was designed to assess the effects of HIV and hemophilia per se on neurological function in a large cohort of subjects with hemophilia, and to investigate the relationships between neurological disease and death during follow-up. METHODS: Three hundred thirty-three boys and young men (207 HIV seropositive and 126 HIV seronegative) were evaluated longitudinally in a multicenter, multidisciplinary study. Neurological history and examination were conducted at baseline and annually for 4 years. The relationship between neurological variables, HIV serostatus, CD4+ cell counts, and vital status at the conclusion of the study was examined using logistic regression models. RESULTS: The risks of nonhemophilia-associated muscle atrophy, behavior change, and gait disturbance increased with time in immune compromised HIV-seropositive subjects compared with HIV seronegative or immunologically stable HIV-seropositive subjects. The risk of behavior change in immune compromised HIV-seropositive hemophiliacs, for example, rose to 60% by year 4 versus 10% to 17% for the other study groups. Forty-five subjects (13.5%), all of whom were HIV seropositive, died by year 4. Subjects who died had had increased risks of hyperreflexia, nonhemophilia-associated muscle atrophy, and behavior change. CONCLUSIONS: These results indicate that immune compromised, HIV-seropositive hemophiliacs have high rates of neurological abnormalities over time and that neurological abnormalities were common among subjects who later died. By contrast, immunologically stable HIV-seropositive subjects did not differ from the HIV-seronegative participants. Hemophilia per se was associated with progressive abnormalities of gait, coordination, and motor function.

Adolescent↗
PubMed1996

Thinking outside the box: linkages between admissions and case management.

Admissions gatekeeping can enhance integration of case management efforts focusing on problems prior to care provision. Most effective as a part of the continuum of care currently being called medical management, it helps to eliminate variability and waste in processes. This medical management approach can increase quality of care, reduce cost, and draw outcomes toward a median that payers, patients, and physicians can expect and accept.

Case Management↗
PubMed1992

Biological markers of exposure to benzene: S-phenylcysteine in albumin.

Results of experiments in our laboratory have shown that benzene is metabolized by animals in part to an intermediate that binds to cysteine groups in hemoglobin to form the adduct S-phenylcysteine (SPC). These results suggested that SPC in hemoglobin may be an effective biological marker for exposure to benzene. However, we could not detect SPC in the globin of humans occupationally exposed to benzene concentrations as high as 28 p.p.m. for 8 h/day, 5 days/week. As another approach, we examined the binding of benzene to cysteine groups of a different blood protein, albumin. To facilitate the process, a new method for the precipitative isolation of albumin from plasma was also developed. The isolated albumin was analyzed for SPC by isotope dilution GC-MS. We used this approach to measure SPC in the albumin of F344/N rats exposed by gavage to 0-10,000 mumol/kg benzene. Amounts of albumin-associated SPC increased as a function of dose, followed by a leveling off in the amount of SPC seen at doses greater than 1000 mumol/kg. Levels of SPC were measured in humans occupationally exposed to average concentrations of 0, 4.4, 8.4 and 23 p.p.m. benzene 8 h/day, 5 days/week. Of nine controls, seven had levels of SPC below the limit of detection (0.1 pmol SPC/mg albumin). SPC increased in the exposed groups linearly, giving a statistically significant slope (P less than 0.001) of 0.044 +/- 0.008 pmol/mg albumin/p.p.m. with an intercept of 0.135 +/- 0.095 pmol/mg albumin. From this study, we conclude that SPC in albumin may prove useful as a biomarker for benzene exposure.

Animals↗
PubMed1992

Neurologic testing with somatosensory evoked potentials in idiopathic scoliosis.

A study was undertaken to determine if a somatosensory conduction delay is present in the posterior columns of adolescents with idiopathic scoliosis. Somatosensory evoked potentials were recorded after median and posterior tibial nerve stimulation in 12 adolescent subjects being followed for idiopathic scoliosis with an average age of 14.6 years (range, 12.0-16.6 years). Twelve normal controls matched for age, sex, race, and height underwent identical testing. Evoked potential peak latencies were measured and conduction velocities calculated. Results showed no difference between scoliotics and normal controls. Comparable posterior column conduction velocities were recorded in both groups. If a defect in posterior column function does exist in adolescent idiopathic scoliosis, as previously postulated, it is not reflected by a conduction delay as measured by somatosensory evoked potential testing.

Adolescent↗
PubMed1989

Transient neonatal hyperglycinemia.

Two patients with neonatal seizures and subsequent normal neurological development were found to have nonketotic hyperglycinemia. In both patients, hyperglycinemia resolved at 6 weeks of age. After cerebrospinal fluid glycine levels were normalized, the seizures stopped completely in one child and were markedly improved in the other. The possible mechanisms for the hyperglycinemia are discussed.

Amino Acid Metabolism, Inborn Errors↗
PubMed1988

X-linked infantile spinal muscular atrophy.

Four male infants from three sibships in an extended family were noted to have hypotonia, areflexia, and congenital joint contractures. The findings of electromyography and muscle histology were consistent with infantile spinal muscular atrophy (SMA). Pedigree analysis suggests that this disorder represents an X-linked, recessive form of SMA. Findings in similar kindreds may explain the previously reported increased male-female ratio in infantile SMA.

Biopsy↗
PubMedDate not supplied

Familial schizencephaly.

Schizencephaly is a brain malformation characterized by infolding of cortical gray matter along a hemispheric cleft near the primary cerebral fissures. Although the etiology is unknown, genetic counseling has not been advocated because of its sporadic occurrence. We describe a family with two affected siblings. Both cases were characterized by hemiparesis, lack of gestational or postnatal complications, and diagnostic radiologic findings. We raise the possibility of a genetic etiology in some cases of schizencephaly and suggest a re-examination of the need for genetic counseling.

Cerebral Cortex↗
PubMedDate not supplied

Reversible myopathy due to labetalol.

A severe, generalized myopathy developed in 2 children treated with labetalol. An 11-year-old girl and a 14-year-old boy demonstrated proximal weakness and markedly elevated creatine kinase levels during labetalol therapy. Clinical improvement began immediately when labetalol administration was halted; muscle strength was normal within 2 months. Muscle biopsies were consistent with rhabdomyolysis.

Acute Kidney Injury↗