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Biomedical subjects

M Howard

Publications and source records attributed to M Howard.

At least 181 records · Page 10Linked to original sources
PubMed1987

Interposed abdominal compression-CPR: its effects on parameters of coronary perfusion in human subjects.

Recent literature has emphasized the relationship between coronary perfusion during CPR and the success of resuscitation from prolonged arrest. In this study, aortic and right atrial pressures were monitored simultaneously during modifications of CPR. Three parameters associated with survival or coronary blood flow during CPR were measured: diastolic arterial pressure (DAP), diastolic arteriovenous difference (DAVD), and mean AV difference (MAVD). Standard advanced cardiac life support protocol was used although vasopressors were given by continuous infusion. In a series of two-minute trials, standard CPR, interposed abdominal compression (IAC) CPR, high-compression force (HCF) IAC-CPR, and HCF standard CPR were performed, with each patient serving as his own control. The DAP increased from 25 mm Hg during standard CPR to 43 during IAC CPR (P less than .001) and 50 during HC-IAC-CPR (P less than .001). The MAVD increased from 4 to 8 mm Hg during HCF-IAC-CPR (P less than .05). IAC-CPR had inconsistent effects on the DAVD. Three patients had a return of spontaneous circulation during the modifications of CPR after a mean of 43 minutes of asystole with standard CPR. In the seven autopsied patients, no significant abdominal injury was found. All forms of CPR studies produced DAVD in the majority of patients well below the minimum DAVD needed for resuscitation in animal models of prolonged arrest. Although the interposed abdominal compression seems to offer some advantages over standard CPR, these hemodynamic data suggest that it would be unlikely to improve survival rates appreciably.

Aged↗
PubMed1987

Interleukin 4 is a growth factor for activated thymocytes: possible role in T-cell ontogeny.

We have shown that recombinant or natural interleukin 4 (IL-4) (formerly called B-cell stimulatory factor 1) induces proliferation of activated adult or fetal thymocytes. In the case of adult thymocytes, IL-4 in combination with Con A or phorbol 12-myristate 13-acetate (PMA) stimulated the proliferation of peanut agglutinin (PNA)-negative (-) thymocytes, while PNA-positive (+) thymocytes showed only marginal responses. Further investigation revealed that day 14-17 fetal thymocytes, purified L3T4- LyT2- double-negative adult thymocytes, and single positive L3T4+ LyT2- or L3T4- LyT2+ thymocytes failed to respond to IL-4 or PMA alone but proliferated strongly with both IL-4 and PMA. In contrast, purified double-positive L3T4+ LyT2+ adult thymocytes showed only a marginal proliferative response to these stimuli. Responsiveness of thymic subpopulations to PMA and IL-4 could be inhibited with anti-IL-4 but not with anti-IL-2 monoclonal antibodies, indicating that they were IL-2 independent. Finally, we have observed that supernatants from calcium ionophore and PMA-stimulated adult double-negative L3T4- LyT2- thymocytes induce proliferation of double-negative adult thymocytes. This latter response is inhibited by anti-IL-4 monoclonal antibodies, suggesting that under appropriate stimulation conditions, these immature thymocytes are able to produce IL-4. These observations suggest a role for IL-4 in T-cell ontogeny.

Animals↗
PubMed1987

Downgrading of non-Hodgkin's lymphoma following chemotherapy.

A case of high-grade non-Hodgkin's lymphoma (malignant lymphoma centroblastic) is presented which, following chemotherapy, manifested low-grade histology. The importance of repeated biopsies in cases of persistent or recurrent disease following therapy for lymphoma is emphasized.

Aged↗
PubMed1986

LPS-activated CBA/N mouse B cells respond to anti-Ig and a BSF-1-like factor.

Highly purified small splenic CBA/N B cells show little or no proliferative response to LPS, soluble anti-Ig, LPS plus anti-Ig, or anti-Ig plus the B cell stimulatory factor BSF-1. An excellent proliferative response is obtained, however, if CBA/N B cells are cultured concurrently with LPS, anti-Ig, and a supernatant rich in T cell-derived lymphokines. The pertinent T cell-derived CBA/N B cell co-stimulating factor has the same m.w., isoelectric point range, and hydrophobicity as BSF-1, and co-migrates with BSF-1 throughout a two-step biochemical scheme developed for BSF-1 purification. These data therefore suggest that CBA/N B cells respond to a BSF-1-like lymphokine under appropriate activation conditions. In support of this conclusion, separate experiments demonstrated that unstimulated small CBA/N B cells respond to HPLC-purified BSF-1 by increased expression of membrane-bound class II major histocompatibility antigens. Taken together, these findings indicate that small CBA/N B cells express the receptor for a factor resembling BSF-1, and acquire the capacity to proliferate in response to anti-Ig and this BSF-1-like factor when co-stimulated with LPS.

Animals↗
PubMed1986

Induction of antigen-specific proliferation in affinity-purified small B lymphocytes: requirement for BSF-1 by type 2 but not type 1 thymus-independent antigens.

We report here the role of B cell stimulatory factors in the induction of antigen-specific proliferation of affinity-purified small B lymphocytes. TI-1 antigens such as TNP-LPS and TNP-BA induced proliferation of hapten-binding B cells in the absence of exogenous B cell stimulatory factors. TI-2 antigens such as TNP-Ficoll required the co-stimulator BSF-1 to induce antigen-specific proliferation, and this response could be augmented by IL 1. TD antigens such as TNP-OVA were unable to induce antigen-specific proliferation either in the absence or presence of B cell stimulatory factors, and showed an absolute activation requirement for carrier-specific helper T cells. No role for IL 2 or BCGF II could be found in the factor-dependent proliferative response of hapten-binding B cells to TI-2 antigens, either as primary co-stimulators or as modulators of the response obtained with TNP-Ficoll, BSF-1, and IL 1. In contrast, concentrations of IFN-gamma that were nontoxic for normal B cells and B cell hybrids effectively abrogated the proliferative response of affinity-purified cells to TNP-Ficoll, BSF-1, and IL 1. By all of these criteria, the B cell activation requirements of TI-2 antigens appear to be identical to those previously published for soluble anti-IgM antibodies.

Animals↗
PubMed1986

Differential proliferative responses of B cells from BALB/c and autoimmune NZB mice to B-cell growth factor(s).

Highly purified B cells from NZB mice have altered responses to various stimuli which require additional costimulatory signals supplied by factors present in EL-4 supernatants when compared to age-matched control nonautoimmune strains. Both crude preparations of EL-4 supernatants as well as partially purified BSF-p1 induced peak proliferation in B cells from normal strains of mice only in the presence of another stimulatory signal, anti-mu. In contrast, B cells from autoimmune-prone NZB mice proliferated in response to B-cell growth factors, with an age-dependent variation. Splenic B cells from 16- to 22-week-old NZB mice, an age where pronounced autoimmune disease is not observed, demonstrated a near maximum proliferative response with B-cell growth factors alone. While normal B cells responded maximally to BSF-p1 in the presence of anti-mu, B cells from young adult NZB mice (16-22 weeks of age) were not further stimulated to proliferate upon the addition of anti-mu. Such NZB B cells appeared to lack the requirement for a stimulation signal delivered by anti-mu in order to respond to B-cell growth factors. These results suggested that NZB cells were partially activated in vivo in the preautoimmune state so that subliminal triggers lead to full activation.

Animals↗
PubMed1986

Retention of knowledge and self-care skills after an intensive in-patient diabetes education program.

Diabetes knowledge and self-care skills were studied in 35 adults with IDDM and NIDDM before and after an intensive in-patient education program and 6-12 months after discharge. Knowledge and skills were compared to fasting serum glucose levels and percent ideal body weight (%IBW). Although knowledge improved during hospitalization and knowledge and skills were maintained at follow-up, there was not a significant relationship between fasting serum glucose levels and knowledge or self-care skills or %IBW.

Adult↗
PubMed1985

Postponing sexual involvement among adolescents. An alternative approach to prevention of sexually transmitted diseases.

Over 1,000 teenagers participated in the field test of an educational series designed to help them resist the social and peer pressures that can lead to early sexual involvement. A companion program for parents was designed to help adults better understand the pressures experienced by adolescents and aid the parents in reinforcing the information given to their children. Initial findings indicate skill building may be an important addition to the knowledge-based curriculum commonly used to prevent the spread of sexually transmitted disease among teenagers today.

Adolescent↗
PubMed1985

Genetic recombination of bacterial plasmid DNA: effect of RecF pathway mutations on plasmid recombination in Escherichia coli.

Tn5 insertion mutations in the recN gene, and in what appears to be a new RecF pathway gene designated recO and mapping at approximately 55.4 min on the standard genetic map, were isolated by screening Tn5 insertion mutations that cotransduced with tyrA. The recO1504::Tn5 mutation decreased the frequency of recombination during Hfr-mediated crosses and increased the susceptibility to killing by UV irradiation and mitomycin C when present in a recB recC sbcB background, but only increased the sensitivity to killing by UV irradiation when present in an otherwise Rec+ background. The effects of these and other RecF pathway mutations on plasmid recombination were tested. Mutations in the recJ, recO, and ssb genes, when present in otherwise Rec+ E. coli strains, decreased the frequency of plasmid recombination, whereas the lexA3, recAo281, recN, and ruv mutations had no effect on plasmid recombination. Tn5 insertion mutations in the lexA gene increased the frequency of plasmid recombination. These data indicate that plasmid recombination events in wild-type Escherichia coli strains are catalyzed by a recombination pathway that is related to the RecF recombination pathway and that some component of this pathway besides the recA gene product is regulated by the lexA gene product.

Bacterial Proteins↗
PubMed1984

Management of Acanthamoeba keratitis. A case report and review of the literature.

A recalcitrant corneal ulcer resulted in an extensive corneal opacity requiring penetrating keratoplasty. Histopathologic studies and subsequent cultures established the diagnosis of Acanthamoeba keratitis. A second transplant was performed due to a culture-proven recurrence of the keratitis in both the recipient and the graft, with progressive thinning. This has remained clear for six months on systemic ketoconazole and topical miconazole drops. This case demonstrates the difficulty in initial diagnosis of Acanthamoeba keratitis and the apparent successful medical control of the infection despite transplantation into an infected recipient bed.

Adult↗
PubMed1984

Cardiac function in alcoholics with cirrhosis: absence of overt cardiomyopathy--myth or fact?

Cardiomyopathy in alcoholics is considered to be associated with a low incidence of hepatic cirrhosis. To evaluate cardiac hemodynamics in alcoholic liver disease, left ventricular function in 37 patients with hepatic cirrhosis (group II) was compared with that in 13 normal subjects (group I) matched for age, sex and cardiac size. These groups were contrasted with group III, comprising 32 alcoholics without cirrhosis who had cardiac symptoms but no cardiomegaly or heart failure. Patients with cirrhosis as a group did not differ from normal subjects (group I) in terms of left ventricular filling pressure and cardiac muscle and pump function (cardiac index). However, subgroup IIA (n = 21) had a stroke index significantly less than normal, while subgroup IIB had a significantly increased stroke index and myocardial cardial contractility with a diminished systemic arterial resistance. Similar hepatic abnormalities were present in both subgroups. In group III, left ventricular end-diastolic and aortic mean pressures were significantly elevated compared with values in normal subjects, while cardiac index and indexes of ventricular contraction and relaxation were abnormal. Further examination of patients with cirrhosis indicated that the responses to volume or pressure increments in terms of the level of stroke work for a given filling pressure were most abnormal in group IIA, approximating those of group III. Thus, although overt cardiomyopathy is infrequent in patients with cirrhosis, asymptomatic myocardial disease may assume clinical importance during volume or pressure overload.

Blood Pressure↗
PubMed1984

B cell growth and differentiation factors.

The role of T lymphocytes in regulation of B cell responsiveness has been recognized for over a decade. Early studies assigned part of this regulation to a soluble product, initially designated T cell-replacing factor or TRF. Recently, investigators have discovered a level of factor complexity skillfully camouflaged by this simple term. Accordingly, the concept has now matured to encompass a battery of antigen non-specific, genetically unrestricted soluble factors which govern all aspects of B cell immunity: activation, proliferation, and differentiation. Here, we review our developing knowledge of this area. While many questions remain unresolved, there seems cause for optimism and a hope that increased understanding of these factors and their mode of action will eventually reveal the basis of B cell immunoregulation.

Animals↗
PubMed1983

Interleukin 2 induces antigen-reactive T cell lines to secrete BCGF-I.

Antigen-activated T lymphocytes produce within 24 h of stimulation a factor that is indistinguishable biochemically and functionally from the B cell co-stimulating growth factor, BCGF-I, originally identified in induced EL4 supernatants: Supernatants from antigen-stimulated T cell lines are not directly mitogenic for resting B cells, but synergize in an H-2-unrestricted manner with anti-Ig activated B cells to produce polyclonal proliferation but not antibody-forming-cell development; biochemical studies reveal the B cell co-stimulating factor present in antigen-stimulated T cell line supernatants is identical by phenyl Sepharose chromatography and isoelectric focusing (IEF) to EL4 supernatant BCGF-I. We thus conclude that normal T cells produce BCGF-I in response to antigenic stimulation. Analysis of the mechanism of BCGF-I production by antigen-stimulated T cells showed that optimum amounts of BCGF-I were obtained as quickly as 24 h post-stimulation, and that the factor producing cells in the T cell line investigated bore the Lyt-1+2- phenotype. As few as 10(4) T cells produced sufficient BCGF-I to support the proliferation of 5 X 10(4) purified anti-Ig activated B cells. Finally, the activation of normal T cell lines to produce BCGF-I required either antigen presented in the context of syngeneic antigen-presenting cells (APC) or interleukin 2 (IL-2).

Animals↗