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Biomedical subjects

M L Smith

Publications and source records attributed to M L Smith.

At least 433 records · Page 24Linked to original sources
PubMed1981

Differential response of cycling and noncycling cells to inducers of DNA synthesis and mitosis.

The objective of this study was to determine whether cells in G(0) phase are functionally distinct from those in G(1) with regard to their ability to respond to the inducers of DNA synthesis and to retard the cell cycle traverse of the G(2) component after fusion. Synchronized populations of HeLa cells in G(1) and human diploid fibroblasts in G(1) and G(0) phases were separately fused using UV-inactivated Sendai virus with HeLa cells prelabeled with [(3)H]ThdR and synchronized in S or G(2) phases. The kinetics of initiation of DNA synthesis in the nuclei of G(0) and G(1) cells residing in G(0)/S and G(1)/S dikaryons, respectively, were studied as a function of time after fusion. In the G(0)/G(2) and G(1)/G(2) fusions, the rate of entry into mitosis of the heterophasic binucleate cells was monitored in the presence of Colcemid. The effects of protein synthesis inhibition in the G(1) cells, and the UV irradiation of G(0) cells before fusion, on the rate of entry of the G(2) component into mitosis were also studied. The results of this study indicate that DNA synthesis can be induced in G(0)nuclei after fusion between G(0)- and S-phase cells, but G(0) nuclei are much slower than G(1) nuclei in responding to the inducers of DNA synthesis because the chromatin of G(0) cells is more condensed than it is in G(1) cells. A more interesting observation resulting from this study is that G(0) cells is more condensed than it is in G(1) cells. A more interesting observation resulting from this study is that G(0) cells differ from G(1) cells with regard to their effects on the cell cycle progression of the G(2) nucleus into mitosis. This difference between G(0) and G(1) cells appears to depend on certain factors, probably nonhistone proteins, present in G(1) cells but absent in G(0) cells. These factors can be induced in G(0) cells by UV irradiation and inhibited in G(1) cells by cycloheximide treatment.

Cell Fusion↗
PubMed1981

The effect of intravenous therapy during labour on maternal and cord serum sodium levels.

A total of 113 women in labour were studied prospectively to determine the relation between maternal and cord serum sodium levels and the effect of intravenous infusions of glucose solutions and oxytocin during labour on the mother and infant. Maternal and cord sodium levels were correlated, with no systematic difference between the two, which is consistent with passive diffusion of sodium across the placenta. Glucose infusions and oxytocin caused statistically significant depression of maternal and cord serum sodium levels, but with the quantities used this did not adversely affect the mothers or infants. It is recommended that caution should be exercised in prescribing intravenous therapy during labour and, if more than 500 ml of fluid is required, sodium should be included.

Female↗
PubMed1981

Clinical manifestations of diarrhea in calves infected with rotavirus and enterotoxigenic Escherichia coli.

The susceptibility of gnotobiotic, colostrum-derived, or suckling calves to four bovine rotavirus isolates was found to be age dependent. Calves older than 7 days remained clinically normal, although they excreted virus in their feces and subsequently developed antibody against the virus, Enterotoxigenic Escherichia coli, fed to gnotobiotic, colostrum-deprived, or suckling calves ranging in age from a few hours to 26 days old, only caused diarrhea in animals younger than 24 h old. In contrast, diarrhea was consistently induced in 1- and 2-week-old calves infected with both enterotoxigenic E. coli and rotavirus. In general, diarrhea appeared after a rotavirus incubation period of approximately 3 days and was independent of the order in which the two microbial agents were given, the age of the calf, or the level of circulating rotavirus antibodies. The disease episode coincided with the excretion of rotavirus, rather than enterotoxigenic E. coli, in the feces. Infection with enterotoxigenic E. coli became established within 24 h of inoculation, and in older calves enterotoxigenic E. coli was often excreted in very small numbers and for a longer period than rotavirus.

Age Factors↗
PubMed1981

Value of the gastric aspirate shake test.

The results and predictive value of the gastric aspirate shake test are reviewed in 432 preterm babies admitted to a neonatal unit during a 3-year period. It is concluded that the degree of prematurity is a better indicator of the chance of developing idiopathic respiratory distress syndrome than the test itself.

Gastric Juice↗
PubMed1981

Bradycardia and associated respiratory changes in neonates.

Electrocardiogram and patterns of respiration were recorded continuously in 9 newborn infants having episodes of bradycardia. The episodes were not associated with demonstrable apnoea, either by using an apnoea mattress or by visual observation. The 'non-apnoea' associated bradycardia was always associated with changes in respiratory pattern, of which three different forms could be identified. These were prolonged apnoea if the apnoea alarm failed to trigger, short episodes of respiratory abnormalities associated with body movement (possibly in rapid eye movement sleep), and minor changes in respiratory pattern. It may be appropriate to incorporate a period of delay in heart rate monitoring systems before the alarm sounds, in a similar manner to apnoea alarm systems. We should rely more on heart rate in conjunction with apnoea alarms to detect problems, or produce better systems which detect respiratory flow.

Apnea↗
PubMed1981

Size heterogeneity of immunoreactive prolactin in stored semen and seminal plasma.

The difference between semen and seminal plasma immunoreactive human prolactin (iPRL) correlates with sperm count. Seminal plasma separated from sperm before freezing (SPB), after freezing (SPA), and serum were fractionated by G100 Sephadex chromatography. SPA contained four different molecular weight fractions of iPRL. Each fraction contained approximately 25% of the total iPRL measured. SPB and serum each had three molecular weight fractions and most of the iPRL coeluted with monomeric 125I-hPRL.

Humans↗
PubMed1981

Failure to produce blood pressure changes following pharmacological or surgical depletion of brain serotonin in the spontaneously hypertensive rat.

Spontaneously hypertensive (SH) and normotensive (Wistar-Kyoto, WKY) rats were examined for blood pressure changes following depletion of CNS serotonin (5-HT) by 3 separate techniques: (1) p-chlorophenylalanine, (2) 5,7-dihydroxytryptamine, and (3) a lesion of the dorsal and median raphe nuclei. All of these procedures failed to alter blood pressure in either hypertensive or normotensive rats, despite marked reductions (75-85%) in forebrain 5-HT. Moreover, treatment of 10 day-old hypertensive rat pups with intracisternal injections of 5,7-DHT (10 microgram) failed to alter the development of hypertension despite a 75-80% decrease in spinal cord 5-HT. These findings, which show that 5-HT depletion does not alter blood pressure in the SH or the WKY rat, do not lend support to the idea that 5-HT is involved in the regulation of blood pressure or in the development and maintenance of hypertension in the SH rat.

5,7-Dihydroxytryptamine↗
PubMed1980

Mode of delivery and survival in babies weighing less than 2000 g at birth.

A retrospective study of babies weighing less than 2000 g at birth admitted over a four-year period to Nottingham City Hospital Neonatal Unit showed a higher incidence of lower Apgar scores and the need for intubation in babies born by caesarean section and breech deliveries. Mortality in those delivered by the breech (35%) was statistically higher than those by caesarean section (10%) or vertex (14%). It is concluded that small babies born by breech delivery have a higher mortality than when delivered vaginally and should have the benefit of caesarean section.

Apgar Score↗
PubMed1980

The clinical response of gnotobiotic calves, pigs and lambs to inoculation with human, calf, pig and foal rotavirus isolates.

The infectivity, pathogenicity and immunogenicity of 5 human, 6 calf, 2 pig and 2 foal rotavirus isolates were studied in gnotobiotic calves, piglets and lambs. Three of the human isolated produced subclinical infection in newborn gnotobiotic piglets and the piglets developed neutralising antirotavirus antibody. When challenged with pig rotavirus 2 weeks later, the piglets did not develop diarrhoea, but rotavirus was detected in the faeces. In contrast, piglets inoculated with the other 2 human isolates failed to show evidence of infection and there was no specific antibody detected. These piglets developed diarrhoea when challenged 2 weeks later with pig rotavirus. The 4 human isolated failed to infect gnotobiotic calves an lambs.

Animals↗
PubMed1980

Raised maternal serum alpha-fetoprotein levels and low birth weight babies.

In a retrospective study of low birth weight babies (less than 2.5 kg) born in one year it was found that statistically more maternal serum alpha-fetoprotein levels were above twice the median level than a control group of mothers producing larger babies (more than 3 kg). However, from the results the test cannot be accepted as being a prospective indicator or as a screening test of low birth weight in pregnant women.

Female↗
PubMed1980

Coding assignments of double-stranded RNA segments of SA 11 rotavirus established by in vitro translation.

The segmented double-stranded (ds) RNA genome of the simian rotavirus SA 11, after denaturation, can be translated in a cell-free protein synthesizing system. Of the 11 genome segments, 9 can be resolved on polyacrylamide gels and thus could be individually isolated and translated, providing a means of identifying the polypeptide encoded by each segment. On the basis of electrophoretic mobility of products in sodium dodecyl sulfate-polyacrylamide gels, the probable gene-coding assignments of dsRNA segments 1 to 6 were determined. RNA segments 1 to 4 code for polypeptides I1, I2, I3, and I4, respectively; segment 5 codes for a polypeptide very similar in mobility to a minor polypeptide present in SA 11-infected cells, O1A; and segment 6 codes for the major inner-capsid polypeptide I5.

Capsid↗
PubMed1980

Proteus mirabilis meningitis and cerebral abscess in the newborn period.

Three cases of Proteus mirabilis meningitis in neonates are reported, in 2 of which abscess formation was proved neuroradiologically. All neonates with P. mirabilis meningitis warrant a CAT scan, as does any newborn infant with meningitis who has a continuing pleocytosis after adequate treatment with antibiotics.

Brain Abscess↗
PubMed1980

Characterization of a suppressor T-cell chronic lymphocytic leukemia with ADCC but not NK activity.

A patient with T-cell chronic lymphocytic leukemia (T-CLL) is reported whose cells demonstrate in vitro suppression of normal lymphocyte mitogen stimulation. The patient, who remains in Rai's clinical stage 0 on no therapy after more than 24 mo of observation, has shown a less aggressive clinical course than is usually attributed to T-CLL. His peripheral blood lymphocytes (PBL) were characterized by functional assays as well as surface markers. Over 90% of the patient's PBL formed rosettes with sheep erythrocytes and were lysed by two T-cell-specific antisera plus complement, while less than 1% bore surface immunoglobulins, and only 3% had complement receptors. In addition, 45% of the PBL demonstrated Ia-like antigens, more than 50% expressed a receptor for the Fc portion of IgG(T gamma), and most of the sheep erythrocyte rosettes were inhibited by theophylline. The patient's cells failed to respond to several mitogens and they caused marked suppression of lymphoproliferative responses to normal PBL to phytohemagglutinin (PHA) and concanavalin A (Con-A). The patient's lymphocytes also exhibited antibody-dependent cytotoxic activity (ADCC) against antibody-coated nucleated target cells, but lacked demonstrable natural killer (NK) activity. This patient's T-CLL cells appear to represent the clonal expansion of a subset of T cells with a previously undescribed pattern of suppressor and cytotoxic activities.

Adult↗