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Biomedical subjects

M W Hess

Publications and source records attributed to M W Hess.

At least 55 records · Page 3Linked to original sources
PubMed1982

Macrophage functions in antimicrobial defense.

In the present short review article, we discuss some recent findings regarding the role of macrophages in antimicrobial defense. Problems that are briefly considered include the production of monocytes and its modification in infectious diseases; the role of circulating monocytes and "fixed" macrophages in the blood stream; emigration of monocytes from the vascular bed and their accumulation at sites of microbial attack; role of macrophages in immune responses; stimulation and activation of these cells including secretory functions; attachment to their surface and phagocytosis of microorganisms; microbicidal activities of macrophages; their role in granuloma formation; inherited and acquired deficiencies of macrophage functions. Emphasis is placed on currently unresolved problems.

Animals↗
PubMed1982

Leucocyte activation and the assessment of leucocyte locomotion.

Leucocyte activation by different agents does not result in a uniform pattern of parallel responses. Some activities have synergistic and others antagonistic effects on directional locomotion in vitro. No reliable correlation between chemotaxis on the one hand and other leucocyte activities such as crawling movements, adhesion to solid substrata and chemokinesis has been firmly established. Therefore, the assessment of chemotaxis by measuring orientation is presumably the only reliable quantitative measure for chemotaxis.

Cell Adhesion↗
PubMed1982

Divergency between incidence of microscopic and macroscopic metastases.

In a rat fibrosarcoma model (D-12), the incidence of macroscopic metastases was generally low but critically dependent on the site of the primary tumor implant; surgical removal of the primary tumor either induced or markedly enhanced the outgrowth of macroscopic metastases (Keller 1981). The present histological and biological findings indicate that dissemination of neoplastic cells and colonization of draining lymph nodes is a spontaneous, early occurring and continuing process. The incidence of micrometastases within lymph nodes by far exceeded the incidence of macroscopically evident metastases. Other evidence suggests that the growth characteristics of D-12 tumor cells derived from metastases are not measurably different from D-12 cells inducing primary tumor growth.

Animals↗
PubMed1982

The role of 2-mercaptoethanol in the stimulation of spleen cell cultures: increased uptake of cystine into the TCA-soluble pool.

A sensitive system for the study of the mechanism of action 2-mercaptoethanol in stimulating of mouse spleen cell cultures is described. In this system the triggering of stimulation of cells by a mitogen or antigen was dependent on the presence of 2-mercaptoethanol (2-ME) in the medium. To obtain a similar stimulatory effect, 2-ME could be replaced by L-cystine or L-cysteine in the presence or absence of a mitogen. In the presence of a mitogen and below the saturation level, cystine was more effective than cysteine. By increasing in this system, the cystine concentration, to the double of that of the basal medium, a strong stimulation of cells was produced. Conversely, in the absence of mitogen, cysteine was significantly more effective than cystine. Addition of 2-ME led to an increased entry of [14C]L-cystine into the TCA-soluble pool of cells while the thiol had no influence on the uptake of a mixture of different amino acids. We conclude that in this system the role of 2-ME is to enable the utilization of otherwise ineffectively low concentrations of cystine by enhancing the entry of this amino acid into the amino acid pool of the cells.

Animals↗
PubMed1982

Enhancement of formylmethionyl-leucyl-phenylalanine-induced directional locomotion of human neutrophils by serum low-density lipoproteins.

Human low-density lipoproteins (LDL) significantly increased neutrophil locomotion in a gradient of the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (FMLP), while LDL alone had no effect on either directional or random locomotion. The enhancing effect on directional locomotion was constantly observed at FMLP concentrations of 10(-8) M and 5 X 10(-8) M after addition of 50 microgram LDL/ml.

Cell Movement↗
PubMed1982

Immature tubular liver with focal nodular trabecular hyperplasia.

An unusual disorder of liver development, which is to our knowledge not described in the literature, was observed in a female infant who died, at the age of 25 weeks, of the sequelae of portal hypertension. At the time of autopsy, the enlarged liver revealed multiple small nodules histologically composed of trabecular hepatic tissue, whereas the remaining liver parenchyma consisted of hepatocytes arranged as tubular structures. Based on comparisons of these morphologic features with the different steps of normal hepatogenesis, we suggest that the disorder is the result of a partial arrest of liver differentiation with focal progression of maturation in the hyperplastic nodules. This assumption is supported by the observation of hepatocytes reacting with anti-alpha-fetoprotein antibodies in the tubular part of the liver, this being absent in the trabecular nodules.

Cell Differentiation↗
PubMed1982

Involution patterns of the human thymus. I Size of the cortical area as a function of age.

Thymic tissue obtained at autopsy from 123 victims of sudden death, ranging from neonates to individuals older than 80 years and predominantly male, was studied with histometric techniques, i.e. a combination of test point analysis and planimetry on unit optical fields. The pattern of 'natural' age-dependent involution of the thymic cortex was examined using computerized mathematical models. The range of variations of results was greatest in children and young adults, followed by the very old, then the middle age group. In a first approximation, regression for thymic cortical volume in individuals older than 15 years corresponded better to a negative exponential than to a negative linear function of age. Best fits for the data suggest at least a two-component negative exponential function of age, with a steeper slope of the regression for individuals beyond the age of 30 years. Extrapolation on a log-normal plot of regression lines for thymic cortical involution points to near-zero values at an age range below the estimated maximum human life span, corresponding to the steepest slope of survival curves in Western Europe.

Adolescent↗
PubMed1981

Modulation of concanavalin A-induced lymphocyte stimulation by human low-density lipoproteins.

Spleen lymphocytes and T cells were stimulated by concanavalin A in the presence of various concentrations of human low-density lipoproteins (LDL). The proliferative responses were measured by [14C]thymidine incorporation. Low LDL doses (5-50 microgram/ml) significantly enhanced the stimulation of splenic lymphocytes and T cells. Further, LDL had the capacity to partially relieve the suppression produced by supraoptimal doses of concanavalin A.

Animals↗
PubMed1981

Nonspecific esterase in human lymphocytes.

A substantial proportion of human peripheral lymphocytes exhibits esterase activity as demonstrated by cytochemical techniques using hexazotized pararosanilin as coupling agent and different alpha-naphthyl compounds, in particular alpha-naphthyl-acetate, as substrates. Esterase-positive lymphocytes showed one or several dots of the reaction product. Plasma cells and macrophages also exhibited marked esterase activity but with diffuse distribution of the reaction product throughout the cytoplasm. The substrate specificity, the time course and the pH optimum of the cytochemical reaction were determined. The results indicate that these lymphocyte esterases are identical with acid lipases. The number of esterase-positive cells reaches a plateau well below 100% (85% for blood lymphocytes) even with optimal staining procedures. The relation between esterase activity and other so-called lymphocyte markers such as sIg and the capacity to form spontaneous rosettes with sheep red blood cells was investigated in peripheral human blood lymphocytes. A fair correlation between rosette formation and esterase activity was found and most of the esterase-positive cells were sIg-negative. However, the fit was never complete. The results suggest that esterase activity is largely characteristic for small peripheral T cells. Almost all blast cells formed following stimulation with Con A or PHA were esterase-positive. Histochemical studies showed that the large majority of the thymocytes in the cortex lacked esterase activity. In lymph nodes, a low proportion of esterase-positive cells was found in the germinal centers, whereas most lymphocytes in the paracortical are were esterase-positive.

Adolescent↗
PubMed1981

Amyloid-containing renal interstitial cell nodules (RICNs) associated with chronic arterial hypertension in older age groups.

A highly significant correlation is demonstrated between the presence in older persons of medullary renal interstitial cell nodules (RICNs) containing amyloid and increased heart weight indicative of chronic arterial hypertension. By contrast, the population with amyloid-free RICNs 1) showed heart weights comparable to those of controls and 2) had a mean age about 11 years less (56.7 +/- 9.6 vs 68 +/- 12 years) than the group with amyloid-containing RICNs. In a series of 55 autopsy cases presenting with RICNs, no individual was younger than 30 years. In two cases, in which fresh material was available, histochemical reactions suggested that the RICNs contained APUD amyloid. It is speculated that fully functional RICNs may evolve on a compensatory base counteracting an increase in mean arterial blood pressure and that the deposition of amyloid within RICNs could be associated with, or be an expression of, a reduced endocrine function of these structures, finally resulting in the development of arterial hypertension.

APUD Cells↗
PubMed1980

The in vitro immune response in the absence of serum and its proteins: stimulating activity of zymosan.

In the absence of serum and its components, zymosan, together with 2-mercaptoethanol present in the medium, stimulated the in vitro primary immune response. Zymosan was effective at a concentration of as low as 2.5 microgram/ml. Removal of macrophages using iron powder resulted in higher recoveries of plaque-forming cells in the presence of zymosan but not of fetuin. Since insoluble zymosan may be easily removed from the culture, the test system described might be suitable for the identification of specific control factors secreted by cells during the in vitro immune response.

Animals↗
PubMed1980

Nuclear antigens: characterization of the acidic nuclear ribonucleoprotein-Sm-antigen complex by analytical and preparative isoelectric focusing.

The soluble ribonucleoprotein nuclear antigen (RNP), associated with the Sm antigen and present in extracts of rabbit thymus acetone powder, was purified by ion-exchange chromatography. Analytical isoelectric focussing (IEF) showed two bands at pH 5.2 and two bands at pH 5.4. After treatment by RNAse these 4 bands disappeared, and a new band with a pI of 6.1, representing the intact protein moiety, appeared. During preparative IEF in granulated gels the antigenicity of RNP was lost. Only the Sm antigen could be detected by counter-immunoelectrophoresis. Fractions with Sm antigenicity refocussed as two intense bands (pI 6.8 and 7.2) and one or two fainter bands (pI 6.1). On reducing SDS-PAGE the SM antigen revealed two bands of apparent molecular weights of about 110,000 and 28,500, indicating a total molecular weight of 138,500.

Animals↗
PubMed1980

The filter technique for measuring leucocyte locomotion in vitro. Comparison of three modifications.

Three forms of filter technique for measuring random and directional locomotion of leucocytes have been compared: (1) the conventional one filter technique of Boyden (lower surface count method); (2) the two filter system with a lower cell-impermeable filter designed to count the cells at the underside of the upper filter as well as those on the lower filter (two filter count method); and (3) two filter systems counting only cells associated with the lower filter (lower filter count method). In some instances all three methods produce qualitatively similar results. In others totally different results are reproducibly obtained with identical cell preparations, media and attractants. Compared to the two filter count method, the lower surface count method and the lower filter count method are not sufficiently reliable. The discrepancies are partly due to errors in measuring the response. They are caused by variable cell adhesion to the filters resulting in a varying distribution of cells between the upper and lower filter and/or detachment of neutrophils from the upper filter. Some of the discrepancies are not due to errors in assessing the response, but to differences in gradient formation and drift of chemokinetic and chemotactic materials from one compartment to the other.

Cell Count↗
PubMed1980

The post-natal development of lymph nodes in mice.

A total of ten major lymph node stations have been studied in ICR-strain mice at various time intervals between birth and the age of four weeks. Comparison of lymph node volumes and of volume changes during the observation period revealed that the mesenteric lymph node (MLN) complex was larger at birth and grew at a faster rate than all other nodes. A distinct numerical increase of cortical lymphocytes in MLN at the end of the first week of life was interpreted to be the result of both immigration of T cells and moderate local proliferation, while the quantitatively more important second phase of growth at the age of between two and three weeks might be the consequence of local lymphocyte production. The comparatively modest changes in lymph nodes removed from the gut (axillary and popliteal nodes) could be explained as being due in large measure to immigration of lymphocytes originating in gut-associated lymphoid tissues (GALT).

Animals↗
PubMed1980

Human lymph node morphology as a function of age and site.

Cervical, axillary, cubital, inguinal, popliteal, and mesenteric lymph nodes from subjects of various ages who had died a sudden death were examined histologically. Care was taken to establish by morphometry the proportional distribution in lymph node cross-sections of cortical, paracortical, and medullary areas. In addition, numbers and surface areas of cross-sectioned germinal centres were registered. Important differences related to age and anatomical site of lymph nodes were established by this survey. Germinal centre formation, particularly evident in infants and children, less so in young adults, and often absent in ageing individuals, was most impressive in lymph nodes normally exposed to antigenic stimulation (mesenteric and cervical lymph nodes). Paracortical and medullary areas exhibited a slight but gradual reduction with advancing age. Replacement of lymphatic parenchyma by fat tissue (lipomatous atrophy) was a characteristic of more peripheral lymph nodes usually subjected to little antigenic stimulation, that is, cubital, axillary, and popliteal nodes. It should be emphasised that both age-related and regional differences have to be taken into account in a meaningful functional interpretation of lymph node morphology.

Adipose Tissue↗