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Biomedical subjects

M Brown

Publications and source records attributed to M Brown.

At least 649 records · Page 36Linked to original sources
PubMed1985

Selection of nonfastidious adenovirus species in 293 cells inoculated with stool specimens containing adenovirus 40.

Of 35 stool specimens isolated and examined in 293 cells, 15 isolates contained adenovirus species 40 (Ad40), and 4 of these 15 isolates also contained a nonfastidious adenovirus species (Ad1 in two cases, Ad18 or Ad31) which was selected over Ad40 during serial passage in the 293 cells. The selection of Ad1 over Ad40 was examined in detail. Restriction analysis of intracellular DNA and the relative infectivity titers of Ad40 and Ad1 at each passage level after the inoculation of 293 cells with a particular stool specimen demonstrated that although the amount of Ad40 DNA synthesized far exceeded that of Ad1, the relative infectivity titer of Ad40 was low. The growth characteristics of Ad40 were then compared with those of Ad1, Ad18, and Ad41 in singly infected 293 cell cultures. One-step growth curves showed the same growth rate in each case, with a latent period of 12 h and a maximum titer at 24 to 36 h postinfection. Yields of infectious Ad40 virus were consistently 100- to 1,000-fold lower than those of Ad1. This difference was reflected by a reduced yield of total AD40 virions (p1.34) as determined by 35S labeling experiments. However, the 3- to 10-fold reduction in total yield of Ad40 virions did not account for the 100- to 1,000-fold reduction in the yield of infectious virus.

Adenoviridae Infections↗
PubMed1985

Assessment of rapid methods of pneumococcal antigen detection in routine sputum bacteriology.

Sputum specimens from 480 patients were examined for the presence of pneumococci by Gram film and culture and for pneumococcal antigen by counterimmunoelectrophoresis, coagglutination, and latex agglutination. Ninety six positive specimens were detected. Gram film and culture provided the most reliable techniques in well taken specimens collected early in the illness before antibiotic treatment had started. More than 70% of the specimens examined were submitted after starting antibiotics, however, and in these specimens, methods of antigen detection proved of greater value than either Gram film or culture. Counterimmunoelectrophoresis, coagglutination, and latex agglutination were similar in sensitivity and specificity, but coagglutination and latex agglutination were much easier to perform and to read.

Agglutination Tests↗
PubMed1985

Intravascular monitoring via the axillary artery.

Axillary artery cannulation was performed in 31 patients in whom the radial arteries were unavailable or unsuitable for cannulation. The artery was first cannulated with an 18-gauge needle, after which a Seldinger guide wire (0.032-inch diameter) was passed, which was used to introduce a 6-inch, 18-gauge Teflon catheter. The mean duration of cannulation was 3.2 days (range 19 hours to 8 days). All patients were assessed for complications of the procedure up to 72 hours after decannulation. No serious complications were encountered. It is concluded that the axillary artery is a safe alternative in the absence of an available radial artery when arterial cannulation is indicated.

Axillary Artery↗
PubMed1985

Neurobiological actions of cysteamine.

Somatostatin (SS)-related peptides act within discrete brain regions to inhibit adrenal epinephrine (E) secretion, to prevent hypothermia, and to produce hyperthermia. Depletion of brain concentrations of these SS-related peptides using cysteamine (CSH) or central administration of an SS receptor antagonist increases adrenal E secretion and impairs thermoregulation. These actions of CSH and the SS receptor antagonist are reversed by administration of SS into the central nervous system. These results support the hypothesis that endogenous brain SS-related peptides are involved in the regulation of adrenal E secretion and thermoregulation.

Adrenal Cortex↗
PubMed1985

Immunologic memory to phosphocholine. VII. Lack of T15 V1 gene utilization in Xid anti-PC hybridomas.

CBA/N mice carrying the Xid defect fail to make antibodies expressing the T15 idiotype in response to immunization with PC-KLH. Antibodies predominating in the Xid response have binding properties characteristic of group II antibodies that emerge in the memory response in BALB/c; the prototype group II antibody utilizes a VH gene product distinct from the V1 gene product expressed by T15 idiotype-positive antibodies. To examine VH gene usage in the anti-PC response of Xid B cells, hybridomas were produced from Xid mice immune to PC-KLH. Four hybridomas possessing properties typical of the predominant group II antibody response in Xid mice and two representing minor components of the response were studied. Analysis of DNA by Southern blot hybridization revealed that none of the hybridomas utilized the T15 V1 gene segment, nor did they share use of a common VDJ gene product. These results indicate that Xid group II antibodies either make use of different VH gene segments or use the same VH in combination with various D and JH segments.

Animals↗
PubMed1985

Uncrossed and crossed inhibition in the inferior colliculus of the cat: a combined 2-deoxyglucose and electrophysiological study.

The cat inferior colliculus (IC) was studied with 2-deoxyglucose (2-DG). By presenting high-frequency tone bursts to one ear and white noise bursts simultaneously to the other, a band of reduced or inhibitory labeling was revealed in the central nucleus (ICC) of the IC ipsilateral to the ear receiving the tone bursts. It was concluded that this ipsilateral inhibition might be related to the organization of excitatory/inhibitory units in ICC. In the opposite ICC, narrow bands of increased labeling were seen. In some animals, the positions of single units were marked, and tone frequencies were presented under 2-DG, which were the same as these units' characteristic frequencies (CFs). The positions of the units coincided with the position of the inhibitory bands, indicating that they were functional isofrequency-inhibitory contours. Unlike higher auditory centers, the binaural inhibitory areas were in register with and not orthogonal to the excitatory isofrequency contours. The inhibitory contours were generally larger than the excitatory contours and became even larger in more caudal sections. Both the inhibitory and excitatory contours extended into dorsal cortex areas of IC. In two other cats, high-frequency tone bursts and white noise bursts were presented to the same ear, and both a band of increased and a band of reduced labelling were found in the IC contralateral to this ear. The inhibitory band was always lateral to the excitatory band and was often smaller. They did not become larger in more caudal sections. The position of a unit in one cat was marked by pontamine sky blue, and the position of the unit coincided with the position of the excitatory band. It was concluded that this lateral inhibitory band represents high-frequency inhibitory sidebands of cells with CFs lower than the stimulating tone. It is concluded that the 2-DG method might reveal hitherto unknown inhibitory systems if stimuli could be combined with diffuse stimuli that raised the general background activity of sensory systems.

Acoustic Stimulation↗
PubMed1985

Acute poisoning by selenious acid.

A 2 yo male child ingested approximately 15 ml of a Gun Blue solution containing selenious acid, nitric acid and copper nitrate. He was immediately given milk and vomited spontaneously blood-stained food with a garlic smell. He was admitted to our Centre less than 3 hr following ingestion. An esophago-gastroscopy showed a second degree burn of both esophagus and stomach. He became comatose and had to be ventilated mechanically. Metabolic acidosis, leucocytosis, hyperglycemia and hemoconcentration were also observed. During the following day he developed a severe intestinal distension, a cardiomyopathy (CPK = 1,302, cardiac arrhythmia), and moderate hepatic, renal and pulmonary dysfunctions. Plasma selenium concentration was 285 micrograms/L and the maximum urinary concentration was 28,459 micrograms/L. After 4 days, his condition had improved considerably and he was about to be extubated when he suddenly developed acute respiratory distress. A similar episode occurred 24 hr later. His lung function progressively deteriorated; later he required the use of an extracorporeal membrane lung. Legionella dumofii was found the causative agent. He died 17 d after ingestion despite aggressive treatment. Acute selenious acid poisoning and its relation to Legionnaire's disease is discussed.

Acid-Base Imbalance↗
PubMed1984

Quantitative aspects of metal ion binding to certain transfer RNA anticodon loop modified nucleosides.

Magnesium and manganese ions bind strongly to the unusual transfer RNA anticodon loop nucleotides, N-[(9-beta-D-ribofuranosyl-9H-purin-6-yl)carbamoyl]-L-threonine 5'-monophosphate (pt6A) and uridine-5-oxyacetic acid 5'-monophosphate (pV). Potentiometric measurements have shown that the delta G for metal ion-pt6A complex formation is 2-3-times more exothermic than for AMP. Electron-nuclear longitudinal dipolar relaxation data yielded manganese-ligand atom distances which permit a three-dimensional construct of the complex in which metal is coordinated to the phosphate, carboxylate of the threonine side-chain (with the nucleotide in the anti glycosidic conformation) and N7 of the adenine ring. Similarly, manganese binds strongly to pV, involving phosphate and carboxylate functions. It is possible that a facet of the functional role of these unusual residues is to chelate magnesium ions and in so doing permit optimum anticodon loop conformational stability and stability of tRNA-mRNA-ribosome complexes.

Anticodon↗
PubMed1984

Inherited chondrodysplasia punctata due to a deletion of the terminal short arm of an X chromosome.

We studied two families with an inherited deletion of the short arm of an X chromosome (Xp) in which affected male offspring have epiphyseal stippling in infancy (chondrodysplasia punctata), nasal hypoplasia, ichthyosis, and mental retardation. The presence of ichthyosis and the apparent pattern of X-linked recessive inheritance prompted investigation of the short arm of the X chromosome through studies of genetic markers and focused cytogenetic analysis. Biochemical studies suggested that there was a deletion of three genes previously mapped to the X-chromosome short arm, including the steroid sulfatase locus, the Xg locus, and the M1C2X locus. Prometaphase chromosomes demonstrated a deletion of Xp at p22.32 in the affected boys, in their obligate-carrier mothers, and in 11 of 25 women at risk as potential carriers. The women carrying the Xp deletion had normal gonadal function and fertility but were shorter than the noncarriers in their families (P less than 0.00001). These findings have implications for the genetic organization of this portion of the human X chromosome and demonstrate that small cytogenetic abnormalities may account for disorders with apparent mendelian patterns of inheritance.

Adolescent↗
PubMed1984

A high macrophage content in human breast cancer is not associated with favourable prognostic factors.

The macrophage contents of 40 human primary breast cancers were ascertained using three separate macrophage membrane markers. Four prognostic factors (lymph node status, tumour size, histological grade and oestrogen receptor status) were determined concurrently in these mammary carcinomas. No significant relationship was found between the macrophage content of the mammary carcinomas and any individual prognostic factor. When the patients were grouped according to whether they had 0-2 or 3-4 high risk factors, however, the macrophage content was significantly greater in those tumours with the poorer prognosis, regardless of the marker used to enumerate the cells. A high macrophage content, therefore, is not associated with favourable prognostic factors in breast cancer. Indeed, the present study has revealed the reverse to be the case.

Axilla↗
PubMed1984

Inhibitory contours in the inferior colliculus as revealed by the 2-deoxyglucose method.

2-Deoxyglucose experiments were carried out during which tone bursts were presented to one ear of cats, while white noise bursts were presented to the other ear. Autoradiography revealed that the tones had produced clear bands of reduced labelling in the ipsilateral inferior colliculus, in addition to the expected band of increased labelling in the contralateral inferior colliculus. The positions of the bands or contours appeared to be organized tonotopically into iso-frequency inhibitory contours.

Animals↗