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Biomedical subjects

M L Scott

Publications and source records attributed to M L Scott.

At least 19 recordsLinked to original sources
PubMed1992

Prevalence of three mutations in the Gs alpha gene among 24 families with pseudohypoparathyroidism type Ia.

Pseudohypoparathyroidism type Ia (PHP-Ia), an inherited multi-hormone resistance syndrome, is associated with deficient cellular activity of the alpha-subunit of the guanine nucleotide-binding protein (Gs alpha) that stimulates adenylyl cyclase. We determined prevalence of three recently described mutations in exons 1 and 10 of the Gs alpha gene among 24 unrelated patients with PHP-Ia. Restriction analysis was used to detect two mutations that produce unique RFLPs, and allele-specific oligonucleotide hybridization was used to detect the other mutation. As none of these mutations were not found, genomic DNA was analyzed with denaturing gradient gel electrophoresis to screen for other mutations in exon 10. Mutations of the initiation codon and exon 10 in the Gs alpha gene thus rarely (< or = 4% each) cause PHP-Ia and the Gs alpha gene mutations causing PHP-Ia are heterogeneous and unique to each pedigree.

Adenylyl Cyclases↗
PubMed1992

Recovery of consummatory feeding behavior after bilateral lesions of the cerebral-buccal connectives in Aplysia californica.

In the sea hare, Aplysia californica, consummatory feeding behavior is selectively abolished by bilateral crushes of the cerebral-buccal connectives and recovers by postlesion day 13. Recovered biting responses are initially weak and increase in magnitude gradually with time. The lesions do not affect appetitive feeding behavior or unrelated reflexive behaviors. Thus, feeding in Aplysia can be used to examine the neural basis of behavioral recovery after CNS injury.

Animals↗
PubMed1992

Prediction of response to lithotripsy--the use of scanning electron microscopy and X-ray energy dispersive spectroscopy.

A single urine sample was obtained from each of 38 patients before and immediately after treatment with a Wolf Piezolith 2300. Each sample was analysed for crystals using scanning electron microscopy and X-ray energy dispersive spectroscopy. In all cases it was possible to make a stone diagnosis prior to treatment and there was 100% correlation between the pre- and post-treatment diagnosis. All stones smaller than 90 mm2 on plain X-ray cleared with piezoelectric lithotripsy alone, regardless of composition. Larger stones composed of calcium oxalate were all successfully fragmented, but 5 of 15 mixed or phosphate stones failed to respond.

Adolescent↗
PubMed1991

Neuromuscular organization of the buccal system in Aplysia californica.

The intrinsic muscles and peripheral nerves in the buccal system of the sea hare Aplysia californica were studied to build a foundation on which to base future investigations of feeding in intact animals. A detailed description of the bilaterally paired intrinsic muscles is given identifying previously unreported muscles. Each of the six buccal nerves (n1-n6) and the cerebrobuccal connective (CBC) have been characterized in several respects. Cell bodies in the buccal ganglion with projections into each of the buccal nerves have been identified via the cobalt backfilling technique. All nerves contain axons of cell bodies in the ipsilateral as well as the contralateral ganglia. For each nerve, there is a consistent pattern in the distribution of cell bodies in the paired ganglia with the number of cell bodies in the contralateral ganglion being less than or equal to the number in the ipsilateral ganglion. Although the total number of backfilled cell bodies varies among the nerves, their size ranges are similar with the majority being small. Nerves 1, 2, 4, 5, and 6 provide motor innervation to the intrinsic buccal muscles in varying degrees with nerve 4 supplying all the intrinsic muscles; nerve 2 supplies only one. The axon composition of each nerve was scrutinized and revealed large numbers of axon profiles, the majority of which were less than 2 microns in diameter. The present study provides a framework for analysis of feeding behavior in Aplysia californica.

Animals↗
PubMed1991

v-abl causes hematopoietic disease distinct from that caused by bcr-abl.

v-abl, the oncogene transduced by Abelson murine leukemia virus, was first characterized by its ability to transform lymphoid cells. bcr-abl, the oncogene formed by a t(9;22) translocation thought to occur in human hematopoietic stem cells, is detectable in almost all cases of chronic myelogenous leukemia (CML), a malignancy of granulocytic cells. bcr-abl also causes a CML-like syndrome in mice whose bone-marrow cells are infected with a retrovirus transducing the gene. More recent reports have suggested that v-abl can, however, cause a disease similar to CML. We demonstrate here that v-abl, when transduced in a helper virus-containing system, causes disease similar to, but distinct from, the CML-like syndrome induced by bcr-abl. Animals whose bone marrow has been infected by v-abl virus develop modest splenomegaly, marked granulocytosis, and malignant disease of several hematopoietic cell types. Unlike animals with CML-like disease resulting from bcr-abl, the polymorphonuclear leukocytes from animals infected with a v-abl construct do not contain the v-abl provirus at a significant frequency. Histopathologic analysis also shows significant differences between the diseases caused by v-abl and bcr-abl.

Abelson murine leukemia virus↗
PubMed1991

Peptidergic motoneurons in the buccal ganglia of Aplysia californica: immunocytochemical, morphological, and physiological characterizations.

We used physiological recordings, intracellular dye injections and immunocytochemistry to further identify and characterize neurons in the buccal ganglia of Aplysia californica expressing Small Cardioactive Peptide-like immunoreactivity (SCP-LI). Neurons were identified based upon soma size and position, input from premotor cells B4 and B5, axonal projections, muscle innervation patterns, and neuromuscular synaptic properties. SCP-LI was observed in several large ventral neurons including B6, B7, B9, B10, and B11, groups of s1 and s2 cluster cells, at least one cell located at a branch point of buccal nerve n2, and the previously characterized neurons B1, B2 and B15. B6, B7, B9, B10 and B11 are motoneurons to intrinsic muscles of the buccal mass, each displaying a unique innervation pattern and neuromuscular plasticity. Combined, these motoneurons innervate all major intrinsic buccal muscles (I1/I3, I2, I4, I5, I6). Correspondingly, SCP-LI processes were observed on all of these muscles. Innervation of multiple nonhomologous buccal muscles by individual motoneurons having extremely plastic neuromuscular synapses, represents a unique form of neuromuscular organization which is prevalent in this system. Our results show numerous SCPergic buccal motoneurons with widespread ganglionic processes and buccal muscle innervation, and support extensive use of SCPs in the control of feeding musculature.

Animals↗
PubMed1991

The parental origin of the single X chromosome in Turner syndrome: lack of correlation with parental age or clinical phenotype.

We have used X- and Y-linked RFLPs to determine the origin of the single X chromosome in 25 live-born individuals with Turner syndrome. We determined that 18 individuals retained a maternal X (Xm) and that seven retained the paternal X (Xp). No occult mosaicism was detected. We found no differences in either maternal or paternal ages for the two groups. The ratio of maternal X to paternal X is just over 2:1, which is consistent with the expected proportion of meiotic or mitotic products, with equal loss at each step, given the nonviability of 45,Y. Six phenotypic or physiologic characteristics were assessed: (1) birth weight, (2) height percentile at time of testing, (3) presence of a webbed neck, (4) cardiovascular abnormalities, (5) renal abnormalities, and (6) thyroid autoimmunity. There were no significant differences in birth weights or heights between the girls who retained the maternal X or the paternal X. In addition, no differences between the groups could be appreciated in the incidence of the physical, anatomic, or physiologic parameters assessed.

Adolescent↗
PubMed1991

Enzyme techniques in blood group serology: the effect of ionic strength.

Lowering the ionic strength of the solution in which red blood cells were suspended for blood grouping was shown to increase sensitivity and the incidence of 'false' positive results in various papain techniques. A reduction in ionic strength of the solution in which cells were pre-modified increased the titration scores for 'enzyme-only' anti-c, anti-e, anti-E and anti-D. Suspension of papain pre-modified cells in lower strength solutions for antigen/antibody reactions had the same effect.

Blood Grouping and Crossmatching↗
PubMed1990

A fast and efficient method for quantification of monoclonal antibodies in an ELISA using a novel incubation system.

We have developed a sensitive, reliable, optimized ELISA to measure human IgM monoclonal antibodies using a novel shaking incubator system with short incubation periods of 15 min at 37 degrees C for all stages. The shaking incubator is compared with a static incubator over a range of incubation times and temperatures. For each stage using static incubation conditions the system does not reach a saturation level and the results are inconsistent, unlike the shaking incubator. No 'edge effects' are observed in the shaking system due to even heating from beneath and across the plate. The orbital shaking ensures optimal mixing of reagents which eliminates a diffusion limited reaction rate caused by a depletion of reactants at the solid phase as observed in the static system. The optimized shaking system permits economical use of reagents since the coating antibody can be used at high dilutions.

Antibodies, Monoclonal↗
PubMed1979

Influence of vitamin B-6 upon reproduction and upon plasma and egg cholesterol in chickens.

Vitamin B-6 deficiency in the laying hen causes an immediate anorexia, loss of body weight, greatly reduced body fat stores and severe effects upon primary and secondary sex characteristics resulting in severely reduced hatchability culminating in complete cessation of egg production. While inanition may have been largely responsible for involution of the ovaries and oviducts in the vitamin B-6 deficient hens, regression of combs and wattles appears to be a more specific sign of vitamin B-6 deficiency. Serum cholesterol levels of vitamin B-6-deficient hens were lower than those of hens receiving an adequate diet. Egg cholesterol values remained relatively constant regardless of dietary B-6 levels or of alterations in serum cholesterol. No ataxia or mortality was observed in vitamin B-6-deficient hens or roosters. The effects of vitamin B-6 deficiency were almost completely reversed upon repletion of the hens with adequate dietary vitamin B-6.

Animal Feed↗
PubMed1979

Effects of interstimulus interval on latency of the brainstem auditory evoked potential.

Peak latency of the inferior collicular response (wave V) of the brainstem auditory evoked potential (BAEP) increases with decreasing interstimulus interval (ISI). The present research investigated relative peak shifts of major components of the BAEP in an attempt to identify the source of the observed shift in wave V. Peripheral as well as central transmission times (CTT) were computed for 9 young adults between an ISI of 100 msec and an ISI of 10 msec. The results indicate that shifts in wave V latency with changing ISI are due to a combination of central and peripheral processes. The magnitude of the shift observed for wave V was approximately 0.50 msec. This increase in latency was accounted for by an average 0.29 msec increase in peripheral transmission time, a 0.14 msec increase in CTT between waves I and III, and a 0.07 msec increase in CTT between waves III and V. The results suggest a dual process underlying latency changes in wave V of the BAEP as a function of decreasing ISI. These are peripheral adaptation or fatigue and central processes that may include short-term habituation.

Acoustic Stimulation↗
PubMed1978

Heat increment associated with dietary protein, fat, carbohydrate and complete diets in salmonids: comparative energetic efficiency.

The heat increment (HI) of feeding, which is the increased heat production following consumption of food by an animal, accounts for as much as 30% of the ingested metabolizable energy (ME) in mammals and birds. The purpose of these experiments was to measure the HI associated with the feeding of a complete diet and purified fat, protein, and carbohydrate to salmonids. Measured amounts were fed and the heat production was measured by direct calorimetry. Increased heat production was observed about 30 minutes after feeding and remained elevated for 1 to 5 hours, depending on the amount and type of material fed. The HI of protein was much lower with fish than with mammals and amounted to less than 5% of the ingested ME. The HI's of carbohydrate and protein were not significantly different from each other but both were higher than fat. The HI, when complete diets were fed, was less than 3% of the ME. The net energy of protein is higher for fish than for birds or mammals. A major part of the superior energetic efficiency of fish is due to the low energy cost of protein metabolism.

Animals↗