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Biomedical subjects

J D Miller

Publications and source records attributed to J D Miller.

At least 325 records · Page 18Linked to original sources
PubMed1986

Variations in pressure-volume index and CSF outflow resistance at different locations in the feline craniospinal axis.

Pressure volume index (PVI) and cerebrospinal fluid (CSF) outflow resistance (Ro) were estimated in spontaneously breathing anestheized cats by the bolus injection test under normal conditions and also under abnormal conditions produced by slow infusion of saline into the CSF space. Bolus injections were made separately into the lumbar subarachnoid space, cisterna magna, and lateral ventricle. The mean PVI values in the lumbar sac, cisterna magna, and lateral ventricle under normal conditions were 0.70, 0.71, and 0.64 ml, respectively; not significantly different from each other. Saline infusion lowered PVI significantly at every site; PVI values in the lumbar sac, cisterna magna, and lateral ventricle were 0.54, 0.52, and 0.53 ml, respectively; not significantly different from each other. Indirect values of PVI were calculated from the pressure responses observed at sites other than where the bolus had been injected. These indirect PVI values were always greater than PVI at the injection site under normal conditions, but differences between direct and indirect PVI values were abolished during saline loading of the CSF space. The Ro was estimated under normal conditions in the lumbar sac, cisterna magna, and lateral ventricle to be 81.6, 85.6, and 110.3 mm Hg/ml/min, respectively. The lateral ventricle Ro was significantly higher than at other places. These findings suggest that, when there is no blockage in the craniospinal axis, the pressure response to a bolus change in CSF volume is freely transmitted, direct measurements of PVI are independent of location, and indirect measurements are larger because of "buffering" in the CSF space. When PVI is lowered and buffering capacity is exhausted, these differences between direct and indirect PVI values disappear.

Animals↗
PubMed1986

Changes at the base of skull and cervical spine in Down syndrome.

Lateral films of the skull base and upper cervical spine in flexion, extension, and neutral positions in 165 patients with Down syndrome, ranging in age from 16 to 60 years, were analyzed. There is a 20% incidence of atlantoaxial subluxation with a marked preponderance in men (24% incidence compared to 15% in women). In addition, there is a high incidence of degenerative changes at the C2-3 and C3-4 cervical interspaces, especially in patients over 37 years of age; these are unusual sites when compared to the normal population in which the degenerative changes are most often at the C5-6 and C6-7 levels. Four patients demonstrated subluxation at cervical interspaces other than C1-2 and six had congenital fusion of either vertebral bodies or facets in the cervical region. Several patients also had flattening of cervical vertebrae; 20% of patients had nonaeration of the sphenoid sinus and 46% had partial aeration.

Adolescent↗
PubMed1986

The formation of learning sets by the chinchilla in an auditory discrimination task.

The performance of 9 chinchillas (Chinchilla lanigera) in a completely computer-automated sound-discrimination experiment was observed using stimulus pairs from a library of 180 complex sounds. Each sound of a pair was 0.2-2.08 sec in duration, separated by an interval of 250 +/- 125 msec. A modified "go/no go" paradigm was used. Licking behavior at a water-delivery tube was occasioned by keeping Ss at about 85% of ad-lib weight by water deprivation. After habituation and blank-trials training stages, sound discrimination was required: If the sounds of a pair were identical, no response was required; if they were different, a fleeing response (crossing a mid-cage barrier) was required. Each problem set utilized a different sound pair, for a total of 90 problems. Therefore, Ss learned to perform general auditory discriminations, not sound-specific discriminations. The chinchillas quickly learned to respond, but not at a rate consistently higher than 75 %-correct. The results were compared to those of other studies of sensory discrimination in monkey and chinchilla. Suggestions were made for minor improvement of the paradigm for use in future sound-discrimination tasks.

Animals↗
PubMed1986

Inguinal neuralgia: a review of 50 patients.

Inguinal neuralgia, an uncommon condition, can readily be diagnosed if the anatomy of the sensory nerves of the lumbar plexus is understood. The authors review 50 patients with this condition, pointing out the importance of injury to these nerves, not only on the anterior abdominal wall but also in the retroperitoneal space on the posterior abdominal wall. Successful treatment is achieved by surgical section of the nerves. First the inguinal region is explored; if this does not result in cure the authors recommend retroperitoneal section of the nerve.

Adult↗
PubMed1985

Ca2+ release by inositol trisphosphate from Ca2+-transporting microsomes derived from uterine sarcoplasmic reticulum.

Microsomes derived from pregnant uterine sarcoplasmic reticulum, isolated by differential and sucrose density gradient centrifugation, accumulates Ca2+ in the presence of ATP. Inositol trisphosphate caused release of this Ca2+, in a dose dependent manner. 40% of the Ca2+ that can be released by the ionophore A23187 was released by 5 microM inositol trisphosphate. Removal of Mg by EDTA prior to addition of inositol trisphosphate did not change the course of Ca2+ release. These results indicate that by mobilizing intracellular Ca2+, inositol trisphosphate may be the link between hormonal stimuli and smooth muscle contraction.

Animals↗
PubMed1985

The work of a regional head injury service.

A survey was done of the workload involved in conducting a programme in which all degrees of severity of head injury are managed in one unit staffed by neurosurgeons. Of 1919 patients admitted to the unit in 1981, 93 were classed as severe (in coma), 210 as moderate, and 1616 as minor (fully conscious or confused only) on admission. Although the proportion of intracranial haematomas, multiple injuries, life-threatening complications, and deaths was highest in severe cases, the work of looking after the very large numbers of moderate and minor cases was as great as that of looking after severe cases as defined by number of investigations, operations, and complications, morbidity, and duration of hospital stay. In 1982 the admission policy was changed so that temporary loss of consciousness was no longer an indication for admission. This change resulted in a 24% reduction in number of admissions. Seat-belt legislation, enacted early in 1983, was followed by a further 21% reduction in the admission rate and this was maintained in 1984. Not all of this latter reduction can, however, be attributed to the wearing of seat belts.

Cerebral Hemorrhage↗
PubMed1985

13C NMR study of the biosynthesis of toxins by Fusarium graminearum.

13C NMR spectroscopic investigations on the biosynthesis of mycotoxins produced by Fusarium graminearum (M69) were carried out through the incorporation of [1-13C]- and [2-13C]acetate precursors. The major secondary metabolites produced by this species in still culture were deoxynivalenol (3,7,15-trihydroxy-12,13-epoxytrichothec-9-en-one), 15-acetyldeoxynivalenol, zearalenone, and butenolide. [1-13C]- and [2-13C]acetate were incorporated in alternate carbon atoms in zearalenone, consistent with the head to tail condensation of nine acetate units. The trichothecenes were enriched in a manner consistent with the condensation of three mevalonate units. 13C/13C couplings, observed between C-5 and C-12, as well as between C-6 and C-15 of 15-acetyldeoxynivalenol, confirms the current hypothesis of formation of the trichothecene ring system by cyclization of farnesyl pyrophosphate. The incorporation pattern in ergosterol is also consistent with a mevalonate origin, while the adjacent incorporation of acetate methyl groups in butenolide suggests a glutamate precursor. The degree of enrichment in the secondary metabolites, which ranged from 3 to 10% at each carbon site, was observed in the 13C NMR spectra of the crude fungal extracts to be dependent on the timing of acetate addition to the culture. The specific toxins produced together with the quantity of each, were also found to be dependent on the timing of acetate addition. Competition between the three biosynthetic pathways of secondary metabolism, i.e. polyketide, mevalonate, and amino acid for the labeled acetate in this organism is a complex function of culture conditions.

Acetates↗
PubMed1985

Calcium mobilization, water balance, and growth in embryos of the agamid lizard Amphibolurus barbatus.

Embryos of the agamid lizard Amphibolurus barbatus are at developmental stage 29 of Dufaure and Hubert at the time of oviposition. Mobilization of calcium and other nutrients from the yolk proceeds slowly for the first half of incubation, during which time embryonic growth also proceeds slowly. During the second half of incubation, however, embryos withdraw calcium and other nutrients from the yolk very rapidly, and growth rates are correspondingly high. Approximately 60% of the calcium used by developing embryos is obtained from the yolk, but fully 40% of their requirement is met by calcium mobilized from the eggshell. Very little calcium remains in residual yolk of hatchlings, so this yolk must be used in maintenance metabolism rather than in growth of neonates. No dichotomy exists among oviparous, amniotic vertebrates with respect to sources of calcium used by developing embryos, but one does exist with respect to patterns of mobilization of this element. Whereas calcium is extracted from yolk of embryonic reptiles throughout incubation, it actually is deposited in yolk of embryonic birds after the midpoint in development.

Animals↗
PubMed1985

Indomethacin and salicylate decrease epinephrine-induced glycogenolysis.

Epinephrine (E) produces an immediate (0-30 minutes) rise in hepatic glucose production (Ra), largely due to activation of glycogenolysis; thereafter, E-stimulated gluconeogenesis becomes the major factor maintaining glucose production. To investigate the possible role of arachidonic acid metabolites on Ra during E stimulation, we infused E in trained conscious dogs before and during administration of two inhibitors of arachidonic acid metabolism, indomethacin (INDO) and salicylate (S). On separate days, experimental animals were treated with both oral and IV INDO and oral acetylsalicylic acid and IV sodium salicylate. Ra and glucose utilization (Rd), both in mg x kg-1 min-1, were calculated by isotope dilution using 3-3H-glucose. After achieving steady state specific activity, control (C) and experimental animals (n = 6 per group) received E (0.1 ug x kg-1 min-1) for 150 minutes, raising plasma levels to approximately 1500 pg/mL in each group. In C, plasma glucose (G; mg/dL) rose by 17 +/- 5 at 10 minutes and 19 +/- 3 at 20 minutes due to an initial spike in Ra (2.7 +/- 0.2 to 4.9 +/- 0.5; P less than 0.01) at 10 minutes. INDO and S treatment attenuated this initial (10-20 minutes) rise in G (P less than 0.05) due to a lower stimulated Ra at 10 minutes (3.3 +/- 0.1 with INDO; 3.0 +/- 0.5 with S; P less than 0.05). After 20 minutes Ra was not different in the 3 groups; no overall differences in Rd, glucose clearance, or plasma insulin levels occurred with INDO or S treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗