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Biomedical subjects

J M England

Publications and source records attributed to J M England.

At least 73 records · Page 4Linked to original sources
PubMed1978

The determinants of irreversibly sickled cells in homozygous sickle cell disease.

The relationship between the irreversibly sickled cell (ISC) count and other haematological parameters has been investigated. Positive correlations occurred with the MCH, MCHC, and with two expressions of intracellular Hb S content. Since the ISC has a high MCHC, the positive correlations with MCHC and with factors derived from the MCHC may be difficult to evaluate. Negative correlations occurred with total haemoglobin and Hb F. The MCHC was found to affect the relationship between HbF and ISC count, a low MCHC being associated with, and probably determining, lower ISC counts at any level of Hb F. It is proposed that a low MCHC may inhibit ISC formation and the practical implications of this are discussed.

Adolescent↗
PubMed1977

Mitochondrial growth and division during the cell cycle in HeLa cells.

The growth and division of mitochondria during the cell cycle was investigated by a morphometric analysis of electron micrographs of synchronized HeLa cells. The ratio of total outer membrane contour length to cytoplasmic area did not vary significantly during the cell cycle, implying a continuous growth of the mitochondrial outer membrane. The mean fraction of cytoplasmic area occupied by mitochondrial profiles was likewise found to remain constant, indicating that the increase in total mitochondrial volume per cell occurs continuously during interphase, in such a way that the mitochondrial complement occupies a constant fraction( approximately 10-11(percent)) of the volume of the cytoplasm. The mean area, outer membrane contour length, and axis ratio of the mitochondrial profiles also did not vary appreciably during the cell cycle; furthermore, the close similarity of the frequency distributions of these parameters for the six experimental time-points suggested a stable mitochondrial shape distribution. The constancy of both the mean mitochondrial profile area and the number of mitochondrial profiles per unit of cytoplasmic area was interpreted to indicate the continuous division of mitochondria at the level of the cell population. Furthermore, no evidence was found for the occurrence of synchronous mitochondrial growth and division within individual cells. Thus, it appears that, in HeLa cells, there is no fixed temporal relationship between the growth and division of mitochondria and the events of the cell cycle. A number of statistical methods were developed for the purpose of making numerical estimates of certain three-dimensional cellular and mitochondrial parameters. Mean cellular and cytoplasmic volumes were calculated for the six time-points; both exhibited a nonlinear, approx. twofold increase. A comparison of the axis ratio distributions of the mitochondrial profiles with theoretical distributions expected from random sectioning of bodies of various three-dimensional shapes allowed the derivation of an "average" mitochondrial shape. This, in turn, permitted calculations to be made which expressed the two-dimensional results in three-dimensional terms. Thus, the estimated values for the number of mitochondria per unit of cytoplasmic volume and for the mean mitochondrial volume were found to remain constant during the cell cycle, while the estimated number of mitochondria per cell increase approx. twofold in an essentially continuous manner.

Cell Division↗
PubMed1977

Rabies virus protein synthesis in infected BHK-21 cells.

Rabies virus specific polypeptide synthesis was examined under hypertonic conditions, which selectively inhibit cellular protein synthesis. The rabies virus proteins (L, G, N, M1, M2) were synthesized throughout the course of infection, with little change in their relative rates of synthesis. The rates of synthesis of the G and M1 polypeptides were more sensitive to increasing osmolarity than those of the L, N, and M2 polypeptides. Extrapolation to isotonicity of the results obtained under hypertonic conditions indicated that the molar ratios of the polypeptides synthesized under normal conditions were 0.4 (L), 64 (G), 100 (N), 75 (M1) and 35 (M2). A high-molecular-weight polypeptide (190,000), designated polypeptide L, was repeatedly detected both in infected cells and in extracellular virus. The estimated number of L polypeptide molecules per virion was 33. The synthesis of a viral glycoprotein precursor, designated gp78, , preceded the appearance of the mature viral glycoprotein in infected cells labeled with [3H]glucosamine under isotonic conditions. In cells labeled under hypertonic conditions, little or no mature viral glycoprotein was detected, but a virus-specific glycoprotein with an electrophoretic mobility similar to that of gp78 was observed. This glycoprotein could be chased into mature viral glycoprotein when the hypertonic conditions were made isotonic. These results suggest that a reversible block of viral glycoprotein synthesis occurs under hypertonic conditions.

Animals↗
PubMed1977

Antibody-independent detection of virus-specific glycoprotein synthesis is oncornavirus-infected cells.

A method is described for detecting the synthesis of avian and murine oncornavirus-specific glycoproteins without the use of antibodies raised against viral structural proteins. As applied to cells infected with avian tumor virus, the method served to resolve pr90, the precursor of the major envelope glycoprotein. A virus-specific glycoprotein of about 85,000 daltons, which has several properties expected to a precursor to gp69/71, was detected in cells infected with murine leukemia virus.

Alpharetrovirus↗
PubMed1976

The transport of endogenous vitamin B12 in normal human serum.

1. Serum from normal subjects has been chromatographed on Sephadex G-200 columns and the fractions containing transcobalamins 0, I and II have been identified. 2. The fractions corresponding to transcobalamin I contained, on average, 90% of the endogenous vitamin B12. Only 3% was attached to transcobalamin 0, and 7% was bound to transcobalamin II.

Adult↗
PubMed1976

Measurement of the mean cell volume using electronic particle counters.

Under carefully controlled conditions electronic cell counters, for example the Coulter Counter, Model FN, and Channelyzer, may be calibrated to give MCV values down to as small as 20 fl which agree with those derived from the centrifugation PCV (corrected for plasma trapping) and the red cell count. The MCV values will be too high if the instrument uses a high cell concentration, has a fixed lower threshold, no effective upper threshold and no edit facility. This may partly explain why the Coulter Counter, Model S, when standardized with 4C cell control gives higher MCV values than the Model FN linked to the Channelyzer. The difference is, on average, 2 fl with normal blood samples and 5 fl in cases of microcytic anaemia. It is suggested that standards of low MCV should be used together with those of normal MCV when calibrating the Model S.

Animals↗
PubMed1976

Microcytosis, anisocytosis and the red cell indices in iron deficiency.

Red cell volume distribution curves have been used to measure microcytosis and anisocytosis in normal subjects, blood donors and patients with iron deficiency anaemia. These measurements were more sensitive than the conventional red cell indices for detecting blood donors with a low transferrin saturation. Three stages are suggested as iron deficiency progressively interferes with haemopoietic function. Anisocytosis and an increased percentage of microcytic cells are the first haematological abnormalities to occur and at this stage haemoglobin concentration is usually normal and trasferrin saturation less than 32%. At the second stage the MCV and MCH decline, haemoglobin concentration is generally sub-normal, though not below 9 g/dl, and transferrin saturation is usually below 16%. The final stage of iron deficiency is associated with a low MCHC, a haemoglobin concentration below 9 g/dl and a transferrin saturation of less than 16%.

Anemia, Hypochromic↗
PubMed1976

The haematology of hypothyroidism.

In an unselected series of 202 patients with hypothyroidism anaemia was present on diagnosis in 39 of 172 women and 14 of 30 men. Microcytic anaemia was present in only nine patients in the entire series. The average of the mean corpuscular volume (MCV) of all the patients was 90 fl. Fifty-three of 118 patients who were studied in detail had normal serum concentrations of vitamin B12, folic acid and iron. The haemoglobin was low in 13 of these 53 patients and rose on treatment with thyroxine alone. The MCV exceeded 90 fl in 29 of these 53 patients and in three it was greater than 100 fl. The MCV invariably fell on treatment with thyroxine even if the initial value was within the normal range. Nine of this group of 53 patients had both anaemia and an increased MCV--the macrocytic anaemia of hypothyroidism. A minor degree of anisocytosis of the red blood cells, which was reduced by treatment with thyroxine, was also demonstrated. Acanthocytes were present in the blood films of 32 out of 172 patients but in only five did the abnormal cells comprise more than 0-5 per cent of the red cell population. The incidence of new cases of pernicious anaemia diagnosed concurrently with the hypothyroidism in the carefully studied group of 118 patients was 8-5 per cent. The MCV of hypothyroid patients with low levels of vitamin B12 was often no greater than in patients with uncomplicated hypothyroidism. The MCV is not therefore a useful discriminant in the diagnosis of pernicious anaemia in hypothyroidism. The serum iron concentration was less than 12 mumol/1 in 60 out of 118 patients. The total iron binding capacity of the serum was increased in only 21 of these 60 patients. In 42 hypothyroid patients the low serum iron concentration was not associated with low levels of either vitamin B12 or folate and of these patients 22 were anaemic. Despite the very low percentage saturation of the iron binding capacity in all of these patients with a low serum iron, a lack of iron did not seem to be the usual determinant of anaemia when it occurred.

Acanthocytes↗
PubMed1975

Variations in leucocyte count during menstrual cycle.

The neutrophil counts of seven women, three tkaing oral contraceptives and four nottaking them, showed cyclical variations during the menstrual cycle, most consistentlya fall in the neutrophil count at menstuation. The neutrophil count in women not taking oral contraceptives rose to a peak twice during each cycle. One womennot taking oral contraceptives was studied in detail over eight consecutive menstrualcycles. She showed two neutrophil peaks per cycle and a similiar variation in themonocyte count. The eosinophil count showed a reciprocal relation with the neutrophil count and the basophil count fell in mid-cycle. The changes in her neutrophil count seemed to follow changes in oestrogen level with a delay of one to two days. Oestrogen probably promotes release of neutrophils from the bone marrow rather than from the marginated pool.

Adult↗
PubMed1975

Simple method for automating the differential leucocyte-count.

A simple method is described for analysing leucocyte-volume distribution curves to obtain a differential leucocyte-count. The results derived by this method agree well with the differential counts obtained by microscopical examination of the stained blood-film.

Automation↗