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Biomedical subjects

M H Snow

Publications and source records attributed to M H Snow.

At least 55 records · Page 3Linked to original sources
PubMed1983

An open study of the use of ceftazidime in Gram-negative infections.

An open study of the use of ceftazidime in patients with Gram-negative infections was undertaken in a district general hospital. Ceftazidime was used in three groups of patients: 17 adults with infections due to Pseudomonas sp. or multi-resistant enterobacteria, three children with cystic fibrosis who had chest infections, and two premature neonates with severe pseudomonal pneumonia. The infections in the adult group included respiratory tract (6), urinary tract (4), wound infection (3), abdominal sepsis (2), osteomyelitis and panophthalmitis. In this group, ceftazidime was given as 1-2 g tid intravenously. In three patients, gentamicin was used concurrently and in four metronidazole was added. 76% of the adult group achieved complete clinical cure, all three cystic fibrosis cases improved markedly, and the two neonates showed complete resolution of the pneumonia. No adverse biochemical or haematological side effects occurred, although one patient developed an urticarial skin rash on the last day of a ten-day treatment course which resolved after discontinuing the ceftazidime.

Adult↗
PubMed1983

Axial abnormalities following disturbed growth in mitomycin C-treated mouse embryos.

Primitive-streak and early-organogenesis-stage mouse embryos were treated with Mitomycin C (MMC) by intraperitoneal injection of pregnant females. Skeletal preparations of newborn pups were made and the axial skeleton examined. The treated animals showed a high incidence of:- (1) changed vertebral numbers, (2) malformation of the vertebral column, (3) changed rib numbers and (4) rib abnormalities. These skeletal disturbances tend to be located more posteriorly with later MMC treatment. There is regional variation in the susceptibility of vertebrae to abnormal development. Extra elements may occur in any region of the spinal column and several unique combinations of numbers are reported. The possible origin of these abnormalities and their similarity to some human syndromes is discussed. It is suggested that they may be the consequence of altered growth profiles in interacting tissues during the restorative growth following MMC treatment.

Abnormalities, Drug-Induced↗
PubMed1982

Bacterial meningitis--ten years experience.

Between January 1968 and December 1977, 635 cases of acute bacterial meningitis were admitted to hospitals in the Birmingham Area Health Authority. The epidemiology of these cases was analysed and compared with the 270 cases which were admitted to the regional infectious diseases unit at East Birmingham Hospital (E.B.H.). In children and young adults the meningococcus was the commonest causative organism while over the age of 25 pneumococcal meningitis predominated. Although Haemophilus influenzae was the second commonest infecting organism it was a rare cause of meningitis in school children and adults, only four cases presenting in these age groups in the Birmingham Area. A detailed analysis was made of the symptoms, signs, laboratory investigations and clinical course of the 270 cases treated at E.B.H. The mortality in the patients with pneumococcal meningitis was 30%. In the meningococcal group it was 3.5% and in the haemophilus groups 7.7%. An analysis of the various treatment regimes employed in the 270 E.B.H. patients supports the view that a single antibiotic is sufficient for the therapy of most forms of bacterial meningitis. Intrathecal antibiotic administration is unnecessary in pyogenic meningitis caused by meningococci, pneumococci or H. influenzae.

Adolescent↗
PubMed1981

Satellite cell distribution within the soleus muscle of the adult mouse.

The frequency of satellite cells was quantitated by electron microscopy in five proximal to distal regions of the soleus muscle of adult mice. In all, 236 satellite cell nuclei and 4, 475 myonuclei were counted on 51 transverse thin sections. The mean percentage of satellite cells, as a ratio of satellite cells to myonuclei, per region was found to be 5.4%, 5.3%, 5.0%, 5.2% and 4.9% for the most proximal to distal areas, respectively. Analysis of variance revealed no significant differences between either the regions or the animals studied. The number of satellite cell nuclei per cross-sectional area of muscle was also calculated for each of the five regions, and these values did not vary significantly from the proximal to distal ends of the muscle. Despite the fact that satellite cells were frequently noted in close association with cross-sectional profiles of myoneural junctions, this study establishes that the number of such perisynaptic satellite cells was not large enough to affect significantly the mean percentages of all satellite cells counted within the motor endplate regions(areas 3 and 4) of the soleus muscle. It is concluded from this study that satellite cells are uniformly distributed throughout the whole muscle.

Animals↗
PubMed1981

Proliferation and migration of primordial germ cells during compensatory growth in mouse embryos.

Primitive-streak-stage mouse embryos were treated with Mitomycin C injected intraperitoneally into pregnant females at 6.75--7.0 days post coitum. The newborn mice developed poorly and mortality was high during the suckling period. Many weaned survivors showed impaired fertility and poor breeding performance. Histological examination revealed a paucity of germ cells in the adult gonads. The deficiency was mainly caused by a severe reduction of the primordial germ cell population in early embryonic life, which was not fully compensated for during the compensatory growth phase of the Mitomycin C-treated embryo. Also contributing to such impaired fertility were retarded migration of the primordial germ cells into the genital ridges, poor development of the foetal gonad and secondary loss of the germ cells during gametogenesis in males.

Animals↗
PubMed1981

Autonomous development of parts isolated from primitive-streak-stage mouse embryos. Is development clonal?

The relationship between growth rate and regionalization of amphibian, bird and mammalian embryos is briefly reviewed. In contrast to the others, mammals start gastrulation with few cells but accelerate cell proliferation coincidentally. Experiments are described which demonstrate (1) autonomous development of pieces isolated surgically from such mouse embryos, and (2) an absence of regeneration or regulation. Since such embryos regulate completely after chemically induced random cell death it is postulated that these results reflect developmental determination and a resulting mosaicism that suggests development may have a clonal basis. Maps are drawn, allocating positions to various tissues in the embryo.

Allantois↗
PubMed1980

The in vitro culture of primitive-streak-stage mouse embryos.

The in vitro growth and morphogenesis of mouse embryos from early primitive-streak stage to early-somite stage is described. The embryo culture method employs a static culture system, a conventional chemically defined medium (Dulbecco's modified Eagle's medium), supplemented with additional glucose, glutamine and suitably prepared serum. The method of serum preparation is important for successful culture. Both mouse serum and rat serum support good development of primitive-streak-stage mouse embryos. Over 60% of early-streak stage and about 90% of late-streak stage grow and develop for 48 h in vitro. During the first 24 h in culture, total growth of the embryos as reflected by protein content, size and morphology is the same as in vivo.

Animals↗
PubMed1979

The pituitary-gonadal response to the gonadotrophin releasing hormone analogue D-Ser (TBU)6-Des Gly10-LHRH-ethylamide in normal men.

We have studied the dose-response characteristics of the LHRH analogue D-Ser (TBU)6-Des Gly10-LHRH-ethylamide administered subcutaneously to five normal male volunteers. The relative potency of the analogue is about sixty times (FSH) and forty times (LH) that of the parent peptide and the increased potency and duration of action of the analogue lead to enhanced biological effect in terms of testosterone release. The prolonged duration of action of the analogue suggests that a single daily dosage regime could be used although further chronic studies with this potent analogue should be undertaken in normal volunteers to determine optimum dosage schedules.

Adult↗
PubMed1979

Thyroid stimulating antibodies and metastatic thyroid carcinoma.

A patient with previously treated follicular carcinoma of the thyroid developed Graves' disease with a high titre of thyroid-stimulating antibodies (TSAb). He developed functioning pulmonary metastases leading to hyperthyroidism. Levels of TSAb paralleled the functional status of the metastases suggesting that hyperfunction of the neoplastic tissues was caused by TSAb.

Adenocarcinoma↗
PubMed1979

Dopamine is a physiological regulator of thyrotrophin (TSH) secretion in normal man.

Using a sensitive and precise radioimmunoassay for human TSH we have demonstrated significant elevations in serum TSH levels in euthyroid volunteers following administration of the dopamine receptor blocking drug metoclopramide when compared with placebo. The degree of TSH response is significantly greater in females than in males and is sustained over a 3-hour period after a single oral 10 mg dose of metoclopramide. The degree of TSH release after metoclopramide is inversely related to the basal TSH level suggesting that dopamine is a determinant of low daytime TSH levels and is thus implicated in the circadian rhythm of TSH secretion. Pretreatment with 10 mg of metoclopramide orally, one hour before TRH administration leads to significant enhancement of the TSH response to TRH. Our findings provide further evidence for the physiological inhibitory role of dopamine in the contol of TSH secretion in normal man. The possible mode of action of dopamine and the clinical implications of this neuroregulatory pathway are discussed.

Adult↗
PubMed1978

An autoradiographic study of satellite cell differentiation into regenerating myotubes following transplantation of muscles in young rats.

Satellite cells were traced autoradiographically during the regeneration of skeletal muscle in young Sprague-Dawley rats. Approximately 31% of the satellite cells in uninjured muscles appeared labelled after three injections of tritiated thymidine; none of the myonuclei were labelled in the same muscles. Four to six days after transplanting the radioactive muscles to non-radioactive littermates, regenerating myotube nuclei in the host appeared labelled. Thus, this study confirms that satellite cells in young rats can differentiate into multinucleated myotubes following muscle injury.

Animals↗
PubMed1978

Plasma renin activity following renal transplantation.

Plasma renin activity (PRA) was studied serially for up to 21 days following transplantation in thirteen patients receiving renal allografts. PRA was measured during fasting and recumvency and its relationship to renal function, diuretic administration, plasma sodium, allograft rejection and blood pressure was examined. PRA fell steadily as renal function improved and plasma sodium rose following transplantation and when rejection episodes were excluded an inverse relationship between PRA and renal function could be seen. It is not possible to say whether the changes in PRA and function are causally related or whether changes in plasma sodium alone account for the observed changes in PRA. Some rejection episodes were accompanied by an increase in PRA, but this was not sufficiently consistent to be of value in the diagnosis of rejection. PRA also increased in relation to frusemide-induced fluid loss. There was no relationship in these patients between PRA and blood pressure.

Creatinine↗
PubMed1978

Gastrulation in the mouse: assessment of cell populations in the epiblast of tw18/tw18 embryos.

Homozygous tW18 embryos die prior to organogenesis. They develop gross abnormalities shortly after primitive streak formation. Anatomically, the lesion appears to be confined to the mesoderm with that tissue showing ultrastructural deficiencies and abnormal migration (Spiegelman & Bennett, 1974), and failing to develop in teratomas produced from mutant embryos (Artzt & Bennett, 1972). Analysis of growth rate by determining cell number increase, and by mapping mitotic activity and planes of cleavage in the epiblast shows that the mutant embryos are small but paradoxically show overall a very high mitotic activity, approximately double that of their normal litter mates. They also show a marked disorientation of the planes of cleavage in most of the epiblast. In pre-primitive streak embryos, before gross abnormality is detectable, two types of embryo can be found. One group constitutes the small embryos which also show the mitotic disturbances characteristic of the later stage mutants. The second group, larger embryos, do not show mitotic abnormalities. The tW18 allele thus seems to act several hours before primitive streak formation. Since there is no difference in the amount of cell between mutant and normal embryos until 6.75 days p.c. it seems that arrest in division is the cause of the elevated mitotic index in mutants. Significantly a small region of the epiblast in mutant embryos is free of the mitotic abnormalities characteristic of the tissue as a whole. This region is the so-called proliferative zone (Snow, 1977) and the data suggest that it may be from this region that some of the ectoderm of the later embryos is produced.

Animals↗
PubMed1977

The effects of aging on satellite cells in skeletal muscles of mice and rats.

Myosatellite cells were examined and quantified at the fine structural level of resolution during aging of skeletal muscles in mice and rats. Satellite cells in the soleus and gastrocnemius muscles of animals between eight and 30 months of age appeared, according to morphological criteria, metabolically less active than those examined in immature muscles. In the soleus muscle of the mouse, satellite cells decreased in number from 4.6% at eight months of age to 2.4% at 30 months. This decrease appeared to be due to the passage of some satellite cells into the interstitial space as a result of the formation of external lamina material around the entire satellite cell surface.

Aging↗