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Biomedical subjects

M J Harris

Publications and source records attributed to M J Harris.

At least 91 records · Page 5Linked to original sources
PubMed1994

Unintentional infant injuries: sociodemographic and psychosocial factors.

This prospective study sought to identify sociodemographic and psychosocial risk factors for unintentional infant injuries that occurred in or around the home. It also examined whether social support modified the relationship between high maternal stress and infant injury. The subjects were 367 mothers who were interviewed six to eight weeks after their newborn infants were discharged from the hospital, and approximately one year later, when 132 infants (36%) were reported as injured (burned, poisoned, serious fall, airway problem). Logistic regression analyses established that family conflict was the most significant predictor of unintentional infant injury, followed by fewer than two siblings living in the home at the first interview, and maternal unemployment. In addition, among mothers with high stress, the use of social support resulted in fewer unintentional infant injuries.

Accidents, Home↗
PubMed1994

Three spontaneous mutations at the albino locus in SELH/Bc mice.

The SELH/Bc inbred mouse stock has produced an unusually high number of spontaneous mutations, including sph2Bc, nuBc, a recessive lens opacity, and three mutations at the c locus. Classical genetic and molecular genetic studies were done to investigate the origin of the albino locus mutations. Southern blots probed with the mouse tyrosinase cDNA showed that two of the mutations, cBc and c2Bc, are deletions of exons 1, 2 and 3. The third mutation, c3Bc, showed a disruption, either a rearrangement or an insertion, in the region of exon 1. The deletion of the cBc mutation is anticipated to be large as the mutation has inactivated the Mod-2 locus 2 cM away, and an essential locus for post-implantation survival outside the c-Mod-2 interval, whereas the c2Bc mutation is viable and fertile in homozygotes. Homozygotes for c3Bc are also viable and fertile. We conclude that at least some of the molecular events leading to the three albino mutations were independent. The mutations differ from each other and from the classical albino point mutation. All three new mutations originated from parents who were germline mosaics, and the mutational events were therefore all postmeiotic. All three mosaics shared one common ancestor six generations previously, raising the possibility that an instability of the albino locus might have been inherited. SELH/Bc mice may provide an animal model for the study of mechanisms underlying genetic instability.

Albinism↗
PubMed1994

Neurobehavioral and neurodiagnostic aspects of late-onset psychosis.

The onset of psychotic symptoms later in life requires careful multidisciplinary evaluation, yet may pose significant diagnostic difficulties given current classification schema. Here we describe a patient with new onset of schizophrenia-like symptoms at age 61. Cognitive screening and laboratory tests were within normal limits. However, detailed neuropsychological studies suggested mild to moderate, diffuse cerebral dysfunction, and MR revealed an arachnoid cyst around the right sylvian fissure. Three annual follow-up evaluations demonstrated no additional cognitive deterioration. Neuropsychological findings are discussed along with limitations of current psychiatric nosology and cognitive screening tasks in older patients with new-onset psychosis.

Journal Article↗
PubMed1994

Early course of new-onset tardive dyskinesia in older patients.

The risk of neuroleptic-induced tardive dyskinesia (TD) in older patients is known to be high, yet the course of TD in older patients has not been systematically studied. We followed 69 middle-aged and elderly outpatients newly diagnosed with TD in a naturalistic, longitudinal, prospective fashion. Standardized assessment instruments were administered to measure psychopathology, cognitive impairment, and abnormal movements. We observed a highly fluctuating early course of TD. Although the cumulative proportion of patients whose TD partially remitted was quite high (56% at 3 months, and 80% at 6 months), the cumulative proportion of patients whose TD relapsed (post-remission) was also high (33% at 3 months and 54% at 6 months). These findings may have clinical as well as theoretical implications for TD in older subjects.

Aged↗
PubMed1993

Retinoic acid, cortisone, or thyroxine suppresses the mutant phenotype of the eyelid development mutation, lgMl, in mice.

The development of the mammalian eyelid is one of the last major morphogenetic events during prenatal development. The eyelids originate as outgrowths of epithelium and mesenchyme above and below the eye; they grow and flatten across the eyes, and meet and fuse firmly but temporarily until several days after birth in mice. In mouse lidgap mutants, eyelid development fails. Previously, we have shown that normal eyelid development can be induced in lidgap mutants by maternal treatment with cortisone or thyroxine. These hormones have been reported to interact with members of a receptor superfamily, and their response elements have been shown to induce transcription of hormone-regulated genes; retinoic acid also interacts with members of this superfamily. The purposes of our study were to examine the joint effect of thyroxine and cortisone on induced eyelid development in lidgap-Miller mutant fetuses (lgMl/lgMl), to test for synergism, and also to test whether retinoic acid also induces eyelid development in this mutant. We found that the combined effect of thyroxine and cortisone was significantly greater than that of either hormone alone, but that the dose-response slopes (log dose, probit scale) for eyelid development induced by cortisone alone or by cortisone preceded by 0.1 mg thyroxine were parallel, suggesting that their action is additive, not synergistic. We found that retinoic acid administered on day 14 of gestation induced eyelid development in lgMl/lgMl mutant fetuses, with a significant dose response and ED50 of 24 +/- 6 mg/kg. The response was treatment-time dependent, with optimal responses after day 14 or 11 treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Ataxia and a cerebellar defect in the exencephaly-prone SELH/Bc mouse stock.

SELH/Bc inbred mice have an abnormal mechanism of anterior neural tube closure and 10-20% of embryos have a lethal neural tube closure defect, exencephaly. Our previous studies have focused on this multifactorial threshold trait. However, SELH mice are also characterized by another trait that also shows non-Mendelian transmission ratios, an ataxia recognized in juvenile and adult mice. Here we report our first genetic and morphological studies of the ataxia trait. Recent pedigree records for the SELH colony showed that 7% of the 467 weaned progeny from normal breeding pairs were ataxic; 17 of the 20 pairs produced ataxic progeny. This result was statistically consistent with the hypothesis that all SELH mice have the ataxic genotype, which is expressed in only 7% of them. Genetic studies of an outcross to a normal strain and the subsequent F2 and testcross of the F2 were also done. The results were consistent with a one or two gene locus cause of liability to ataxia in SELH mice. The genetic correlation between exencephaly production and ataxia production for a sample of nine F2 males was 0.35, as expected if both traits are caused by the same genes, but was not statistically significant. In another approach, we examined the morphology of brains from normal and ataxic adult SELH mice. All 20 brains from non-ataxic SELH mice were morphologically normal. In all 18 brains from ataxic SELH mice the cerebellum was abnormal, lacking the vermis, and characterized by a midline fissure. This phenotype in mice has previously been known in Mendelian mutants at the Wnt-1 locus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Histological study of the cranial neural folds of mice genetically liable to exencephaly.

The SELH/Bc (SELH) inbred stock of mice has a high liability to the neural tube closure defect, exencephaly. All SELH embryos close their cranial neural tubes by an abnormal mechanism, lacking elevation and initiation of fusion in the posterior prosencephalon/anterior mesencephalon region. Most embryos complete closure of the cranial neural tube by extension of a more rostral site of fusion, but in 10-20% this process fails, and the embryos are subsequently exencephalic. In this study, transverse histological sections of the cranial neural folds of SELH embryos at the 3-5, 6-8, and 9-11 somite stages were compared to those of two strains with normal neural tube closure, ICR/Bc and LM/Bc. At all stages, consistent morphological differences were observed between SELH and the two normal strains. In 3-5 somite SELH embryos, the divergence of the folds from the neural groove is more angular, the folds are flatter, and their lateral tips appear "hooked" downward. In 6-8 somite SELH embryos, the lateral tips of the folds appear more elongated and in the prosencephalon they are less elevated than in the normal strains. The boundary between neuroepithelium and mesenchyme or surface ectoderm tends to be less clear than normal in SELH lateral tips. In 9-11 somite SELH embryos, divergence of the folds from the neural groove continues to be angular and the lateral folds are splayed horizontally. In addition, the lateral surface ectoderm is abnormally indented and the neuroepithelium/surface ectoderm boundary is more ventral and lateral in SELH than in ICR/Bc and LM/Bc. The hypothesis that the defect in SELH cranial neural folds might involve the cytoskeleton was tested using a fluorescent probe for filamentous actin in 7 somite SELH and ICR/Bc embryos. The actin staining pattern in SELH embryos was like that of normal ICR/Bc embryos, with a strongly staining apical concentration in the neuroepithelium. This suggests that there is no gross cytological abnormality within the neuroepithelium, but does not rule out more subtle defects, such as those involving cytoskeletal function.

Animals↗
PubMed1993

Cavernous adrenal hemangioma.

Cavernous hemangiomas are unusual tumors with a propensity for skin and liver involvement and rarely involving genitourinary organs. We report an unusual case of adrenal hemangioma which was successfully treated surgically. In addition, we review the salient clinical, radiographic, and pathologic features of this disease.

Adrenal Gland Neoplasms↗
PubMed1993

Chylothorax as a complication of radical nephrectomy.

We report a case of chylo-retroperitoneum and chylothorax following an uneventful left radical nephrectomy for renal cell carcinoma, and propose the mechanism of an infradiaphragmatic lymphatic injury with fistulous connection into the chest. Treatment with oral medium chain triglycerides was unsuccessful. Subsequently, total parenteral nutrition in conjunction with chest drainage, retroperitoneal drainage and sclerotherapy successfully treated the chylothorax. To our knowledge chylothorax following radical nephrectomy has not been reported previously in the literature.

Aged↗
PubMed1993

Sensory gating and inhibitory function in late-life schizophrenia.

Although similarities between the cognitive deficits observed in schizophrenia and those observed in aging have been recognized for over 50 years, little work has been done to directly examine these similarities or their implications for late-life schizophrenia. We review studies of prepulse inhibition, habituation, latent inhibition, and negative priming that indicate marked similarities in the patterns of deficits observed in schizophrenia and in aging. We also present new data from preliminary studies of prepulse inhibition and negative priming in which we compare young normal controls, older adult normal controls, and late-life schizophrenia patients. For both measures, both schizophrenia patients and older adults showed an inhibitory deficit relative to young controls. In the case of negative priming, older schizophrenia patients showed evidence of greater inhibitory dysfunction than did normal older adults, suggesting that older schizophrenia patients suffer a deficit resulting from the combined effects of schizophrenia and aging. The implications of these results and directions for future research are discussed.

Acoustic Stimulation↗
PubMed1993

Extrapyramidal motor abnormalities associated with late-life psychosis.

Studies of extrapyramidal motor function in patients with schizophrenia have contributed to our understanding of the phenomenology and therapeutic outcome associated with neuroleptics. An increasing body of literature suggests that extrapyramidal motor abnormalities associated with schizophrenia may be linked to the pathophysiological mechanisms responsible for schizophrenia. Similarly, it has been documented that the extrapyramidal system may be involved in motor abnormalities in patients with Alzheimer's disease (AD). The present study was undertaken to examine motor function in schizophrenia and AD patients with psychosis. Quantitative instrumental procedures were used to examine rigidity, tremor, and bradykinesia in 13 neuroleptic-naive patients with schizophrenia, 13 AD patients with psychosis, and 26 age-comparable controls. Both schizophrenia and AD patients had significantly higher tremor and rigidity scores than did normal subjects. This comparative study of schizophrenia and AD patients with psychosis suggests that the effect of dementia in patients with psychosis is to prolong movement time, whereas abnormal parkinsonian postural tremor tends to be associated with psychosis in the absence of dementia.

Aged↗
PubMed1993

Geriatric care management reduces Medicare losses.

Healthcare costs for the elderly are rising rapidly in the United States. One way for a hospital to control these rising costs is to implement a geriatric care management system. The goal of a such a system is to change the way the hospital treats medically complex Medicare patients and, thus, reduce unnecessary hospital costs. Such a system requires a process for identifying elderly patients in need of geriatric care management services, treating them efficiently, and assessing the system itself. An effective process usually results in significant cost savings for the hospital as well as improved patient care and satisfaction.

Aged↗
PubMed1993

Impression formation in children: influence of gender and expectancy.

The effect of expectancy-congruent and -incongruent information on subsequent impression formation and recall of a target peer was examined. 64 boys and 50 girls (ages 8 to 12) were given an expectancy that a stimulus child was either shy or outgoing. Subjects rated the target on several dimensions (e.g., friendly, shy) and then watched a videotape of a boy or girl confederate acting out a script containing both expectancy-congruent and -incongruent information. Subjects then rated the target child again and freely recalled as much of what the target said as they could remember. Results revealed that when children are presented with both expectancy-congruent and -incongruent information, impression formation appears largely attribute based, and the influence of the initial expectancy appears mitigated. However, ratings of liking appeared to be more influenced by the initial expectancy than by subsequent behavioral information. In addition, the results indicated that many of Maccoby's conclusions regarding the effects of gender on social interactions also apply to children's social information processing, indicating a strong bias toward same-sex peers.

Child↗