Phenotypic and functional properties of murine thymocytes. III. Kinetic analysis of the recovery of intrathymic cytolytic T lymphocyte precursors after in vivo administration of hydrocortisone acetate

The phenotypic and functional properties of cells in the C57BL/6 mouse thymus regenerating after a single dose of 100 mg/kg hydrocortisone acetate (H/C) are described. Functionally, the frequency of anti-H-2d cytolytic T lymphocyte precursors (CTL-P) in thymuses from individual mice was determined by limit dilution analysis of mixed leukocyte microcultures. The initial increase in CTL-P frequency, seen 48 hr post-H/C, was followed at 6 to 8 days by a phase of rapid decrease. The CTL-P frequency returned to a normal level by 28 days post-H/C. Analysis of the results from individual mice suggested that changes in total thymic CTL-P content were independent of the kinetics of thymus regeneration. Phenotypically, whereas the thymus 48 hr after H/C was considerably depleted of Lyt-2+ cells, there followed a rapid increase in the proportion of such cells to normal levels by 14 days post-H/C. In addition, as measured by FLS, a subpopulation of larger, predominantly Lyt-2+ cells was found during the phase of rapid thymic regeneration. With the use of a monoclonal anti-Thy-1.2 antibody, the weakly Thy-1-staining subpopulation of cells was absent from the thymus at 14 days post-H/C. These changes in the phenotypic properties of the post-H/C regenerating thymus were correlated with changes in their functional properties.     

Ultrastructural changes in nurse and follicle cells during late stages of oogenesis in Drosophila melanogaster

Summary During stages 11 and 12, follicle cells surrounding the nurse cells produce lysosomes which presumably aid in the breakdown of the nurse cells. Accompanying a DNA reduction in nurse cell nuclei are several characteristic morphological changes including the appearance of intranuclear rod-like structures and nuclear granules about 300 Å in diameter. Similarities between structures seen in Drosophila nurse cell nuclei and those seen in other organisms are discussed.This research was supported by U. S. Public Health Service Grants 5TIGM903-3 and 1-F1-GM-33, 385-01 and National Science Foundation grant GB-7457.     

On surface geometry coupled to morphogen

An expression is derived for both the Gauss and the Mean curvature of a surface, in terms of three simple cell parameters. The surface is thought of as composed of a single-cell thick sheet of cells joined laterally. The three cellular parameters involved are the ratios of (linear) basal to apical dimension in two orthogonal directions, S1 and S2, and the cell thickness "h". These three parameters may be envisioned as functions of a morphogen or morphogens which vary from point to point over the (middle) surface. As an example, the "reaction-diffusion" equations which are often used to describe pattern-formation in early development can be seen as possible candidates for these morphogens, when the resultant surface deformations are given when the dependence of the three cellular parameters are specified as a function of morphogen concentration. The coupling back of the surface deformations to the set of reaction-diffusion equations is simply given, and is through the dependence on geometry of the Laplacian operator which enters these equations.     

Lung overexpansion increases pulmonary microvascular protein permeability in young lambs

To study the effects of inflation pressure and tidal volume (VT) on protein permeability in the neonatal pulmonary microcirculation, we measured lung vascular pressures, blood flow, lymph flow (QL), and concentrations of protein in lymph (L) and plasma (P) of 22 chronically catheterized lambs that received mechanical ventilation at various peak inflation pressures (PIP) and VT. Nine lambs were ventilated initially with a PIP of 19 +/- 1 cmH2O and a VT of 10 +/- 1 ml/kg for 2-4 h (base line), after which we overexpanded their lungs with a PIP of 58 +/- 3 cmH2O and a VT of 48 +/- 4 ml/kg for 4-8 h. QL increased from 2.1 +/- 0.4 to 13.9 +/- 5.0 ml/h. L/P did not change, but the ratio of albumin to globulin in lymph relative to the same ratio in plasma decreased, indicating altered protein sieving in the pulmonary microcirculation. Seven other lambs were mechanically ventilated for 2-4 h at a PIP of 34 +/- 1 cmH2O and a VT of 23 +/- 2 ml/kg (base line), after which their chest and abdomen were bound so that PIP increased to 54 +/- 1 cmH2O for 4-6 h without a change in VT. QL decreased on average from 2.8 +/- 0.6 to 1.9 +/- 0.3 ml/h (P = 0.08), and L/P was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)     

Differential Expression of a Mycobacterium tuberculosis Protein Recognized by a Mouse Monoclonal Antibody

Murine monoclonal antibodies were produced against Mycobacterium tuberculosis (Mtb) using standard hybridoma procedures. By a whole cell enzyme-linked immunosorbent assay (ELISA), one monoclonal antibody (mAb), HB28, demonstrated high level specific reactivity to Mtb. Western blot analysis demonstrated reactivity to a single 65 kDa Mtb protein in the cell wall extract and culture filtrate. HB28 mAb appears to be recognizing a 65 kDa Mtb protein that is over-expressed by Mtb but not other species under certain culture conditions. Differential expression and detection of this protein by HB28 mAb may have potential for diagnostic applications.     

Risk of breast cancer in relation to the interval since last full term pregnancy.

OBJECTIVE--To examine whether the risk of breast cancer is increased by a recent term pregnancy. DESIGN--Population based case-control study. SETTING--Eight areas in the United States. SUBJECTS--Cases were 2279 multiparous women residents of the eight areas aged 25-49 who were diagnosed as having breast cancer during 1980-2. Controls were 2357 multiparous women selected from the same areas by random digit dialing. MAIN OUTCOME MEASURE--Relative risk of developing breast cancer according to the time interval since last full term pregnancy. RESULTS--The distribution of intervals since the last term pregnancy was similar in cases and controls. Adjusted for age, parity, and age at first term pregnancy, the odds ratios observed for categories of years since the last full term pregnancy were: 0-2 years, odds ratio 1.16 (95% confidence interval 0.84 to 1.59); 3-6 years, odds ratio 1.21 (0.95 to 1.54); 7-9 years, odds ratio 1.04 (0.84 to 1.38); > or = 10 years, odds ratio 1.00 (reference). CONCLUSIONS--Among multiparous women aged 25-49 years there was no association between the risk of breast cancer and the time interval since the last full term pregnancy.     

Barriers to prenatal care for low-income women.

Inadequate prenatal care is associated with poor birth outcomes. Recognizing barriers to care is necessary to improve results. Postpartum in-hospital interviews were conducted with women admitted through emergency departments with no physician of record (n = 69) in 8 Sacramento hospitals during April and May 1991. A focus group of local obstetrician-gynecologists was used to determine physicians'' attitudes about caring for low-income women. We undertook the study in response to an increased number of "no doc" births. The inability to find a physician willing to accept them was reported by the women as the single largest barrier to obtaining care, cited by 64% of women overall and 96% of those who tried but were unable to obtain care. Transportation difficulties were a problem regardless of women''s success in obtaining care and were ranked as the top barrier by women who never tried to obtain care. Physicians cited administrative difficulties and reimbursement levels of Medi-Cal plus extra care requirements and resource dependency of low-income patients as barriers to caring for this population. The value ascribed to prenatal care by women and physicians'' perceptions of women''s attitudes about care contrasted sharply. The link between poor women and physicians providing obstetric services can be fragile. The difficulty finding physicians willing to take them indicates that these women need special support services to ensure adequate care during pregnancy.     

Newspaper as a substrate for cellulolytic landfill bacteria

Five cellulolytic bacterial isolates ( Clostridium and Eubacterium spp.) from a methane-producing landfill were examined to determine their ability to utilize newspaper as a substrate for growth. Solubilization was poor with even the most actively cellulolytic bacteria. The major factor causing the low activity seemed to be that as much as 24% of the newspaper was composed of the high molecular weight polymer lignin, which exerts a protective effect on the attack of otherwise susceptible polymers. The presence of ink on heavily printed paper also reduced the rate of cellulose solubilization. Although the ink did not appear directly toxic to the bacteria it masked the surface of the paper, covering the cellulose fibres and preventing bacterial adhesion to the substrate. The action of the cellulolytic isolates was also strongly inhibited below the optimum growth temperature of 37°C.