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Biomedical subjects

M Birch

Publications and source records attributed to M Birch.

At least 55 records · Page 3Linked to original sources
PubMed1992

A radiographic method for estimating lung volumes in sick infants.

Estimation of lung volumes by conventional methods in sick infants is technically difficult and is the subject of controversy. In this study, we compared both thoracic gas volume (TGV), measured with an infant whole body plethysmograph, and functional residual capacity (FRC), determined by the nitrogen washout technique, to planimetric measurements of anteroposterior chest radiographs in 26 infants with bronchopulmonary dysplasia (BPD). The tidal volume (TV) of each patient was added to TGV and FRC because these were measured at the end of expiration whereas chest radiographs were taken at the end of spontaneous inspiration. The regression equations expressing the relationships between TGV and right+left lung field areas [A+B], and between FRC and lung areas are expressed as follows: [TGV+TV](mL) = 3.3 mL/cm2 x [A+B] cm2 + 24 mL and [FRC+TV](mL) = 3.5 mL/cm2 x [A+B] cm2 - 13.5 mL. Correlation coefficients of 0.9 and 0.7 for TGV and FRC, respectively, suggest a stronger correlation between TGV and lung areas than between FRC and lung areas. Lung areas measured by planimetry correlate closely with physiological measurement of lung volumes. We conclude that the planimetric method is an inexpensive and reliable technique for estimating lung volumes in young infants with BPD when chest radiographs are available.

Bronchopulmonary Dysplasia↗
PubMed1991

Isolation and characterization of human melanoma cell variants expressing high and low levels of CD44.

Variants of the human melanoma cell line LT5.1 were selected for high and low expression of the Mr 90,000 CD44 glycoprotein by using the Hermes-3 monoclonal antibody combined with fluorescence-activated cell sorting. Cells were single cell cloned and clones of CD44 high-expressing and CD44 low-expressing phenotype were isolated. The variants, which exhibited up to a 7-fold difference between high and low expression, have maintained a stable phenotype over a period of 3 months in tissue culture. Northern blot analysis of mRNA from the different clones showed correlation of levels of transcripts with fluorescence-activated cell sorting analysis data. Wound migration assays, utilizing the different clones, showed that the low-expressing clones manifested less motility than did cells showing high levels of CD44. Homotypic aggregation of cells was increased in those cells expressing high levels of CD44, and these variants were also better able to adhere to hyaluronate substrates. All of these activities were inhibited by the presence of anti-CD44 antibody. When injected i.v. into nu/nu BALB/c mice, the low-expressing clones gave significantly fewer lung nodules than the high-expressing clones, although the two variant types did not differ in their capacity to form s.c. tumors in similar mice. These results suggest that the CD44 molecule, possibly as a function of its activities as a hyaluronate receptor, may play a vital role in determining the fate of hematogenously disseminating melanoma cells.

Animals↗
PubMed1991

[Duration of breast feeding].

A longitudinal prospective study was performed to investigate the total duration of breast-feeding. Three hundred and sixty six mothers were followed-up until three years after delivery. At three months, 73% were breast-feeding, at six months 52%, at one year 20% and 1% breast-fed more than three years. Correlations were found between duration of breast-feeding and maternal age, education and social class. Mature mothers who lived under good socioeconomic conditions breast-fed for longer periods than those who were less fortunate in these respects. Mothers who had breast-fed an older child usually breast-fed the next child for a similar period. Breast-feeding has become popular: only 1% did not want to breast-feed at all and 89% of mothers intended to breast-feed their children for six months or more. Solid food was most frequently introduced when the infants were four months old. At six months 4% were still exclusively breast-fed. Even though the mothers now breast-feed longer than previously, only 39% succeeded in breast-feeding for as long as or longer than they had intended.

Breast Feeding↗
PubMed1991

Influence of the mode of delivery on initiation of breast-feeding.

The initiation and the prevalence of breast-feeding after discharge from hospital was investigated in 370 singleton parturients and compared to the mode of delivery. Infants delivered by vacuum extraction or by caesarean section started suckling later, they were more often given formula prescription during the first 4 days, they were less often breast-fed during the night, and their mother's milk 'came in' later, but it did not affect the prevalence of breast-feeding after discharge. A sleepy infant, which was not very willing to suckle, was the most frequent nursing-problem mentioned by the mothers 4 days after delivery. Failure to start breast-feeding occurred in only 2.2% of the women, and after 6 months 52% were still breast-feeding their children.

Analysis of Variance↗
PubMed1991

Cell adhesion receptor expression during melanoma progression and metastasis.

Many steps in melanoma metastasis involve cell-cell or cell-matrix adhesive interactions. The surface molecules which mediate these processes therefore play an important role in regulating melanoma dissemination and their level of expression may alter during the course of tumor progression. Human melanocyte strains and melanoma cell lines have been characterised with regard to levels of cell surface receptors of the integrin family. Increased amounts of at least two integrins, VLA-4 (alpha 4 beta 1) and VnR (alpha v beta 3), appeared to correlate with progression in this tumor, type. A novel VnR composed of an alpha v beta 1 association has been observed in one melanoma cell line and there is the possibility that heterogeneity of integrin composition could affect biological behavior of these tumors. CD44, a cell surface glycoprotein which functions as the major receptor for hyaluronate, is another molecule whose expression increases in transformed cells of the melanocytic lineage. Iterative sorting on the FACS for stable variants, of both human and murine melanomas, expressing low and high levels of CD44 established that lack of expression of this molecule correlated with impaired ability to form pulmonary tumor nodules subsequent to i.v. injection into appropriate recipient mice. These findings illustrate that an understanding of the regulation of melanoma adhesion receptors could provide insights into the process of tumor spread.

Humans↗
PubMed1991

Nasal resonometer: an instrument for the assessment and treatment of hypernasality.

We describe an instrument which enables the measurement of the ratio of nasal to oral sound pressures to be made during normal speech. The technique incorporates a novel phase locking technique which effectively discriminates the spectral characteristic of resonant peaks occurring during nasalized speech from other nasal emissions. The results enable an assessment of the degree of resonance in real time, the trend of diagnostic measurements within a treatment session and the success achieved in reaching targets set during treatment.

Adolescent↗
PubMed1991

The duration of breast-feeding. A longitudinal prospective study in Denmark.

A longitudinal prospective study was performed to investigate the total duration of breast-feeding. Three hundred and sixty-six mothers were followed-up until 3 years after delivery. At 1 month 93% were breast-feeding, at 3 months 73%, at 6 months 52%, at 1 year 20% and 1% breast-fed more than 3 years. Correlations were found between duration of breast-feeding and maternal age, education and social class. Mothers who had breast-fed an older child usually breast-fed the next child for a period of similar length. Solid food was most frequently introduced when the infants were 4 months old. At 6 months 4% were still exclusively breast-fed. Breast-feeding has become popular: only 1% did not want to breast-feed at all and 89% of mothers intended to breast-feed their children for 6 months or more. Even though the mothers now breast-feed longer than earlier, only 39% succeeded in breast-feeding for as long as or longer than they had intended.

Adult↗
PubMed1991

The significance of pregnancy, delivery and postpartum factors for the development of infantile colic.

Infantile colic (IC) is a distressing condition with an unclear etiology. A prospective trial was undertaken to study the hypothesis that medication during labor increases the risk of IC. Of 365 singleton deliveries, 70 (19%) developed IC. The factors associated with a significantly increased occurrence of IC were: a "psychological" complication of pregnancy, a sibling with a history of IC, a bad subjective experience of pregnancy and second parity. No significant association to "true" obstetrical complications or labor occurrences (breech, vacuum extractor, cesarean section, shoulder dystocia, pudendal block, epidural analgesia, general anesthesia or intravenous Syntocinon) was found. Modern management of labor does not increase the risk of IC. Prevention of IC is therefore achieved by psychological support to the pregnant women in the risk groups, and not by depriving her of necessary obstetrical management or pain relief.

Colic↗
PubMed1986

The carriage and delivery of substances to lymphatic tissues by recirculating lymphocytes. II. Long-term selective irradiation of the spleen and lymph nodes by deposition of indium-114m.

Recirculating lymphocytes were used to carry an isotope of indium, In-114m. The isotope has a half-life of 50 days, and emits both gamma and beta particles, properties that may be useful clinically. In-114m-labelled rat thoracic duct lymphocytes (TDL), injected intravenously, migrated to traffic areas in spleen and lymph nodes. The radioactivity was transferred selectively to a resident, radioresistant phagocytic population located within the marginal zone and red pulp of spleen, where it remained for at least 6 weeks. That the isotope was relatively concentrated in traffic areas, but not elsewhere, suggested that In-114m-TDL could be used as a means of producing total lymphoid irradiation without damaging bone marrow. Recipients of In-114m-TDL developed a profound lymphocytopenia within 2-3 weeks of injection but gained weight at a comparable rate to control rats. The effect of In-114m-TDL injection was also examined in rats injected with a rapidly growing, malignant rat leukaemia. In-114m-TDL delayed the onset of the proliferative phase of the leukaemia from 10 days to 20 days in a dose-dependent fashion. Repeated weekly injections of In-114m-TDL prevented the onset of the leukaemia until the injections ceased after 11 weeks. The potential use of In-114m-labelled lymphocytes in diagnosis (by external imaging) or in treatment (by localized lymphoid irradiation) is considered.

Animals↗
PubMed1984

Value of nasogastric tube after colorectal surgery.

To evaluate the effect of tube decompression of the stomach after elective colorectal operations, 97 patients were randomly allocated to postoperative treatment with or without nasogastric tubes. Flatus passed earlier in the patient group without tubes. However, no significant differences were found between the two groups with respect to duration and severity of postoperative paralysis, as measured by occurrence and duration of nausea and vomiting, postoperative peroral fluid intake and time for defecation. The frequencies of postoperative complications were small in both groups and without any difference between groups. Tube decompression of the stomach does not relieve intestinal paralysis after elective colorectal operations. Tube decompression should be used only in patients with paralytic ileus.

Adolescent↗
PubMed1978

Changes in plasma noradrenaline concentration following sympathetic stimulation by gradual tilting.

Plasma noradrenaline concentration was determined by a radioenzymatic method in 10 normal individuals who were subjected to a stepwise tilt through 45 degrees. A gradual increase in noradrenaline was observed with maximal values occurring in most subjects following the full 45 degrees of tilt. Maximal levels were sustained for up to 30 min. In two subjects who fainted, the syncopal episode followed an initial sympathetic postural response as shown by a rise in plasma noradrenaline. For the remaining subjects a significant correlation was found between changes in plasma noradrenaline and mean arterial pressure.

Adult↗
PubMed1977

Plasma-noradrenaline in essential hypertension.

Plasma-noradrenaline (P.N.A.) has been determined in normotensive controls and in patients with essential hypertension while resting and after postural stimulation. A linear relationship was found between age and P.N.A. in normotensives during recumbency and in the upright posture. This relationship did not occur in the hypertensives and was due to raised P.N.A. levels in many younger patients. On standing, ten out of thirty-four patients under the age of 50 years with essential hypertension had significantly greater P.N.A. than the age-matched controls. No differences were found, however, between controls and patients in the older age-group. It is proposed that stimulation of the sympathetic nervous system by postural challenge provides a means for identifying a subgroup of younger patients with essential hypertension in whom sympathetic overactivity may play an important rule.

Adult↗
PubMed1974

Preparation and properties of a phosphoenzyme from the phosphoglucomutase of Micrococcus lysodeikticus.

1. Phosphoglucomutase from Micrococcus lysodeikticus was incubated with (14)C- and (32)P-labelled glucose 1,6-diphosphate and separated from the cofactor on a Sephadex column. (32)P-labelled phosphate (0.7mol/mol of enzyme) was associated with the enzyme, but no (14)C label was. 2. The (32)P-labelled enzyme exchanged its label with the substrates. When the labelled enzyme was incubated in Tris buffer, pH8.3, at 30 degrees C the proportion of exchangeable label slowly fell indicating a half-life of the phosphoenzyme of about 50h. 3. When HClO(4) was added to the labelled phosphoenzyme all of the label was precipitated with the protein and none was released as P(i). On alkaline hydrolysis P(i) was released at a rate comparable with the rate of hydrolysis of the phosphoenzyme from rabbit muscle. 4. We conclude that the phosphoenzyme from Micrococcus lysodeikticus yields a relatively stable, catalytically active phosphoenzyme when treated with cofactor, and that there is no evidence for the formation of an enzyme-glucose 1,6-diphosphate complex. The properties of the phosphoenzyme, which resemble those of rabbit muscle phosphoglucomutase, suggest that the phosphate may be bound to serine.

Animals↗
PubMed1974

The equilibrium constant of the phosphoglyceromutase reaction.

The equilibrium constant of the phosphoglyceromutase reaction was determined over a range of pH (5.4-7.9), in solutions of different ionic strength (0.06-0.3) and in the presence of Mg(2+), at 30 degrees C and at 20 degrees C. The values obtained (8.65-11.65) differ substantially from previously published values. The third acid dissociation constants were redetermined for 2- and 3-phosphoglycerate, and in contrast with previous reports the pK values (7.03 and 6.97 respectively at zero ionic strength) were closely similar. The Mg(2+)-binding constants were measured spectrophotometrically and the values, 286mm(-1) and 255mm(-1) for 2- and 3-phosphoglycerate at pH7 and ionic strength 0.02, were also very similar. From the relative lack of effect of temperature, pH and ionic strength it is concluded that the equilibrium constant differs from unity largely because of entropic factors. At low ionic strength, in the neutral region, the pH-dependence can be attributed to the small difference in the acid dissociation constants, but the difference in dissociation constants does not explain the pH-dependence in the acid region or at high ionic strength. Within physiological ranges of pH, Mg(2+) concentration and ionic strength there will be little variation in equilibrium constant.

Acid-Base Equilibrium↗