Biomedical subjects
K Black
Publications and source records attributed to K Black.
Subacute paraparesis induced by venous thrombosis of a spinal angiolipoma: a case report.
STUDY DESIGN: A case report of spinal extradural angiolipoma, a rare tumor that can cause spinal cord compression, is presented with a complete review of the literature related to this disorder. OBJECTIVES: To discuss venous thrombosis involving the angiolipoma in the development of subacute paraparesis. SUMMARY OF BACKGROUND DATA: This case shows that venous thrombosis of a spinal angiolipoma can precipitate the subacute onset of paraparesis. METHODS: Medical history, physical findings, and the results of imaging and histopathologic studies were analyzed to elucidate the pathogenesis of the patient's subacute onset of paraparesis. A bilateral T3-T7 laminectomy was performed, and although the tumor was extremely hemorrhagic, it was mobilized easily off the compressed dura to achieve resection. RESULTS: The postoperative course was uneventful. One month after her surgery, the patient's myelopathic symptoms had resolved, and the she was able to return to work. CONCLUSION: Because the prognosis after surgical management of these lesions is favorable, the diagnosis of thrombosis involving a spinal angiolipoma should be considered in the differential diagnosis of subacute spinal cord compression.
Expression of oligodendrocytic mRNAs in glial tumors: changes associated with tumor grade and extent of neoplastic infiltration.
We examined the expression of glial- and neuronal-specific mRNAs within human gliomas using in situ hybridization. We found that low-grade astrocytomas contained a high number of proteolipid protein (PLP) mRNA-positive cells and that the number of PLP-stained cells decreased markedly with increasing tumor grade. Interestingly, the ratio of PLP mRNA-stained cells:myelin basic protein (MBP) mRNA-stained cells in normal white matter and low-grade astrocytoma was about 2:1 but approached 1:1 with increasing tumor grade. This parameter appeared to be a good indicator of tumor infiltration in astrocytomas, so we tested this in the analysis of other gliomas. Unlike astrocytomas, oligodendrogliomas were found consistently to contain few PLP mRNA- or MBP mRNA-expressing cells. In contrast, gemistocytic astrocytomas, typically highly invasive tumors, contained high numbers of PLP-positive cells and a ratio of PLP mRNA:MBP mRNA-stained cells of about 1.5:1, similar to low-grade astrocytomas. Nonradioactive in situ hybridization also enabled the morphological identification of specific cells. For example, gemistocytic astrocytes, which were found to be strongly vimentin mRNA positive, contained little glial fibrillary acidic protein mRNA and did not stain for PLP or MBP mRNAs. Neuronal mRNAs, such as neurofilament 68, were observed in small numbers of entrapped neurons within gliomas but were uninformative with respect to predicting tumor grade. Our results suggest that oligodendrocytes survive low-grade tumor infiltration and that glial tumor cells, unlike cell lines derived from them, do not express oligodendrocyte or neuronal mRNAs. In addition, the expression of mRNAs for the two major myelin protein genes, PLP and MBP, could be used to predict the grade and extent of tumor infiltration in astrocytomas.
Staphylococcal meningitis secondary to sacral osteomyelitis in an infant.
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Childhood AIDS, varicella zoster, and cerebral vasculopathy.
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Cognitive testing with culturally diverse children.
This special section discusses how the psychological status of minority children can be enhanced if psychologists adopt an integrated approach in establishing linkages and in examining interactions and reciprocal effects when assessing ethnically, linguistically, and culturally different children. Implications for conducting culturally relevant assessments of intelligence are discussed. A bioecological model for incorporating these suggested techniques into a program evaluation is suggested.
Burkitt's lymphoma of the skull base presenting as cavernous sinus syndrome in early childhood.
Primary non-Hodgkin's lymphoma of the skull base presenting with neuro-ophthalmologic abnormalities or cavernous sinus involvement is very rare in children. We have found only 13 reported cases of cavernous sinus involvement by lymphoma [1]. We report the case of the youngest child diagnosed with Burkitt's lymphoma of the cavernous sinus and sphenoid sinus, whose first presentation was cavernous sinus syndrome with neuro-ophthalmologic findings.
Hand-held blood gas analyzer is accurate in the critical care setting.
OBJECTIVE: To determine the accuracy of a new, portable battery-powered blood gas analyzer when used by nonlaboratory-trained clinicians in the critical care setting. DESIGN: Prospective analysis of blood samples from critically ill patients. SETTING: Large tertiary critical care unit. PATIENTS: Heterogeneous group of medical and surgical critically ill patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Two hundred thirty-nine split blood samples from intensive care patients were analyzed by clinicians in the critical care environment using a new, portable, battery-powered blood gas analyzer (Immediate Response Mobile Analyzer [IRMA], Diametrics Medical, St. Paul, MN). Near-patient measurements were compared with measurements obtained by laboratory technologists using an IL-1312 blood gas analyzer (Instrumentation Laboratories, Lexington, MA) in an established near-patient critical care laboratory. Precision and coefficients of variation were also determined using repeated testing of quality control samples at three levels of pH, PO2, and PCO2. There was good agreement between IRMA determinations and the laboratory. Correlation coefficients ranged from 0.96 to 0.99. Bias and precision (+/-2 SD), respectively, were 0.02 and 0.036 units for pH, -0.3 torr (1.8 kPa) (-0.04 kPa) and 7.2 torr (0.96 kPa) for PCO2 and -3.9 torr (0.52 kPa) and 13.8 torr (1.8 kPa) for PO2. Precision on repeated testing of quality control samples ranged from 0.022 to 0.04 units for a pH of 7.2 to 7.6, 1.2 to 4.6 torr (0.16 to 0.61 kPa) for a PCO2 of 20 to 60 torr (2.7 to 8 kPa), and 3.0 to 7.4 torr (0.40 to 0.99 kPa) for a PO2 of 70 to 160 torr (9.3 to 21.3 kPa). Coefficients of variation ranged from 0.15% to 0.28% for a pH of 7.2 to 7.6, 2.0% to 3.7% for a PCO2 of 20 to 60 torr (2.7 to 8.0 kPa), and 1.7% to 3.6% for a PO2 of 70 to 160 torr (9.3 to 21.3 kPa). Mean turnaround time was 16.5 +/-10.1 mins for the near-patient laboratory and 2+/-0.5 mins for IRMA. CONCLUSIONS: IRMA is accurate and reproducible when used in the clinical setting by nonlaboratory-trained individuals. Nonlaboratory-trained individuals can obtain laboratory results in the critical care setting comparable with the results obtained by trained laboratory technologists. Bedside laboratory testing decreases turnaround time compared with a near-patient laboratory.
Neonatal cerebral arterial thrombosis: protein C deficiency.
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Death by suicide in Grampian 1974-1990', Health Bulletin 1996; 37-44.
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Developing hypothermia: indicators.
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Placebo-controlled trial of safety and efficacy of intraoperative controlled delivery by biodegradable polymers of chemotherapy for recurrent gliomas. The Polymer-brain Tumor Treatment Group.
Chemotherapy for brain tumours has been limited because of difficulty in achieving adequate exposure to the tumour without systemic toxicity. We have developed a method for local sustained release of chemotherapeutic agents by their incorporation into biodegradable polymers. Implantation of the drug-impregnated polymer at the tumour site allows prolonged local exposure with minimal systemic exposure. We conducted a randomised, placebo-controlled, prospective study to evaluate the effectiveness of biodegradable polymers impregnated with carmustine to treat recurrent malignant gliomas. In 27 medical centres, 222 patients with recurrent malignant brain tumours requiring re-operation were randomly assigned to receive surgically implanted biodegradable polymer discs with or without 3.85% carmustine. Randomisation balanced the treatment groups for all of the prognostic factors examined. Median survival of the 110 patients who received carmustine polymers was 31 weeks compared with 23 weeks for the 112 patients who received only placebo polymers (hazard ratio = 0.67, p = 0.006, after accounting for the effects of prognostic factors). Among patients with glioblastoma, 6-month survival in those treated with carmustine-polymer discs was 50% greater than in those treated with placebo (mortality = 32 of 72 [44%] vs 47 of 73 [64%], p = 0.02). There were no clinically important adverse reactions related to the carmustine polymer, either in the brain or systemically. Interstitial chemotherapy delivered with polymers directly to brain tumours at the time of surgery seems to be a safe and effective treatment for recurrent malignant gliomas.
Dyslexia and corpus callosum morphology.
OBJECTIVE: There is evolving evidence that developmental dyslexia is associated with anomalous cerebral morphology in the bilateral frontal and left temporoparietal regions. This study examined the morphology of the corpus callosum, as possible deviations in other important structures are poorly understood in this behaviorally diagnosed syndrome. DESIGN: Magnetic resonance imaging scans were obtained from children with developmental dyslexia and from matched control children. Morphometric measurements were examined to determine if regional differences existed in the corpus callosum between these two groups of children. SETTING: Magnetic resonance imaging studies were completed at Athens (Ga) Magnetic Imaging. PATIENTS AND OTHER PARTICIPANTS: Sixteen developmental dyslexic children (mean age, 9.7 years) and a matched sample of children who were diagnosed as being normal were examined by using a reliable comprehensive diagnostic process. MAIN OUTCOME MEASURES: Using a midsagittal magnetic resonance imaging scan, corpus callosum morphology was evaluated by segmenting the corpus callosum into five regions of interest. RESULTS: Analysis of the corpus callosum revealed that the anterior region of interest (the genu) was significantly smaller in the dyslexic children. Significant correlations existed between reading achievement and the region-of-interest measurements for the genu and splenium. Measured intelligence, chronologic age, and gender were not related to region-of-interest measurements of the corpus callosum. Consistent with previous studies, the dyslexic individuals were characterized by significant psychiatric comorbidity, particularly attention-deficit disorder with and without hyperactivity. Reported familial left-handedness also distinguished the dyslexic children. CONCLUSIONS: Subtle neurodevelopmental variation in the morphology of the corpus callosum may be associated with the difficulty that dyslexic children experience in reading and on tasks involving interhemispheric transfer.
The hglK gene is required for localization of heterocyst-specific glycolipids in the cyanobacterium Anabaena sp. strain PCC 7120.
Mutant strain 543 of the cyanobacterium Anabaena sp. strain PCC 7120 was originally isolated as a Fox- mutant following chemical mutagenesis. Ultrastructural analysis shows that in nitrogen-replete media the vegetative cells of the mutant are more cylindrical and have thicker septa than those of the wild type, while in nitrogen-free media the mutant heterocysts lack the normal glycolipid layer external to the cell wall. Although this layer is absent, strain 543 heterocysts nevertheless contain heterocyst-specific glycolipids, as determined by thin-layer chromatography. The mutation in strain 543 is in a gene we have named hglK, encoding a protein of 727 amino acids. The wild-type HglK protein appears to contain four membrane-spanning regions followed by 36 repeats of a degenerate pentapeptide sequence, AXLXX. The mutation in strain 543 introduces a termination codon immediately upstream of the pentapeptide repeat region. A mutant constructed by insertion of an antibiotic resistance cassette near the beginning of the hglK gene has the same phenotype as strain 543. We propose that hglK encodes a protein necessary for the localization of heterocyst glycolipids and that this function requires the pentapeptide repeats of the HglK protein.
A short-filament mutant of Anabaena sp. strain PCC 7120 that fragments in nitrogen-deficient medium.
Strain 129 is a fragmentation mutant of the filamentous cyanobacterium Anabaena sp. strain PCC 7120. Growing with fixed nitrogen, this mutant forms filaments that are much shorter than wild-type filaments. Following starvation for fixed nitrogen, strain 129 becomes nearly unicellular and forms few heterocysts, although electron microscopy suggests that proheterocysts form while fragmentation occurs. Starvation for sulfate, phosphate, iron, and calcium does not cause this fragmentation. The affected gene in strain 129, fraC, was cloned by complementation and characterized. It encodes a unique 179-amino-acid protein rich in phenylalanine. Insertional inactivation of the chromosomal copy of fraC results in a phenotype identical to that of strain 129, while complementation using a truncated version of FraC results in only partial complementation of the original mutant. Heterocysts could be induced to form in N-replete cultures of strain 129, as in wild-type cells, by supplying extra copies of the hetR gene on a plasmid. Thus, FraC is required for the integrity of cell junctions in general but is apparently not directly involved in normal differentiation and nitrogen fixation.
Spinal cord compression by spontaneous spinal subdural haematoma in polycythemia vera.
A woman with an eight-year history of polycythemia vera presented with numbness and weakness of both legs. A large spinal haematoma was revealed on magnetic resonance imaging which was treated clinically and which subsequently resolved.
Asystole associated with herpes simplex encephalitis.
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Near-patient blood gas and electrolyte analyses are accurate when performed by non-laboratory-trained individuals.
OBJECTIVE: The objective of this study was to determine the accuracy of a near-patient blood gas and electrolyte analyzer when used by non-laboratory-trained clinicians in the critical care setting. METHODS: One hundred eighty-five blood samples (split samples) from 50 intensive care unit patients were analyzed by clinicians in the critical care environment using a near-patient blood gas and electrolyte analyzer (GEM Premier, Mallinckrodt Sensor Systems, Ann Arbor, MI). Near-patient measurements were compared with those obtained by laboratory technologists in an established intensive care unit laboratory. RESULTS: There was good agreement between the near-patient analyzer and the laboratory for pH, PCO2, sodium, potassium, ionized calcium, and hematocrit. Bias and precision were 0.006 and 0.03 for pH, 0.03 and 0.34 kPa for PCO2, 0.78 and 2.61 mmol/L for sodium, -0.11 and 0.12 mmol/L for potassium, -0.007 and 0.05 mmol/L for ionized calcium, and -0.99 and 1.33% for hematocrit. Bias between the laboratory instrument and the bedside analyzer was small for PO2 (-0.56 kPa). However, precision between instruments was significantly higher (2.39 kPa for all PO2 values and 1.61 kPa for PO2 < or = 13 kPa). CONCLUSIONS: The test instrument is accurate and reproducible when used in the clinical setting by non-laboratory-trained individuals. Non-laboratory-trained individuals can obtain laboratory results in the near-patient setting comparable to those obtained by trained laboratory technologists.