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Biomedical subjects

J L Collins

Publications and source records attributed to J L Collins.

At least 109 records · Page 6Linked to original sources
PubMed1988

Cutaneous malignant melanoma in a black patient with neurofibromatosis (von Recklinghausen's disease).

A unique case of a cutaneous malignant melanoma arising in a black man with a familial history of neurofibromatosis (von Recklinghausen's disease) is reported. Although neurofibromatosis is believed to be a disorder of neural crest origin that is associated with a number of different malignancies, a definite association of malignant melanoma with neurofibromatosis has not been reported. The presence of a malignant melanoma arising on the trunk of a black man suggests an association of cutaneous malignant melanoma and neurofibromatosis--a malignancy and genodermatosis, respectively--of ultimate neural crest origin.

Adult↗
PubMed1988

Effect of mycoplasmas on natural cytotoxic activity and release of tumor necrosis factor alpha by spleen cells.

It has been reported that mycoplasma-infected cells are more sensitive to lysis by natural cytotoxic (NC) effector cells and that splenic NC cells release tumor necrosis factor (TNF-alpha) when they lyse sensitive target cells. Here we showed that spleen cells released TNF-alpha when they were incubated with NC-sensitive cells that were infected with mycoplasmas or when they were incubated with mycoplasmas alone, but did not release TNF-alpha when incubated with NC-sensitive cells that were not infected with mycoplasmas. Thus, in the presence of mycoplasmas, spleen cell cultures contain both NC effector cells and free TNF-alpha. Because NC-sensitive cells are also sensitive to free TNF-alpha, when mycoplasma-infected cells were incubated with spleen cells, they were lysed by the combination of NC cells and free TNF-alpha. When NC-sensitive cells that were not infected with mycoplasmas were incubated with spleen cells, they were lysed only by NC effector cells and thus appeared to be less sensitive than mycoplasma-infected cells. These results also suggested that the release of TNF-alpha may be part of a host protective response to mycoplasmas.

Animals↗
PubMed1987

Humans express natural cytotoxic (NC) cell activity that is similar to murine NC cell activity.

The expression of natural cytotoxic (NC) activity is well defined in mice, but poorly defined in humans. In this paper we report that humans express naturally occurring cytotoxic cell activity that recognizes and lyses murine targets that are sensitive to lysis mediated by murine NC cells, but not murine targets that are resistant to lysis by murine NC cells. We present data showing that these naturally occurring human cytotoxic cells and murine NC cells have similar lytic mechanisms. Both the human cytotoxic cells described here, and murine NC cells, use tumor necrosis factor (TNF) to mediate the lysis of sensitive targets. Moreover, targets that resist murine NC-mediated lysis by a protein synthesis-dependent post-recognitive mechanism use a similar mechanism to prevent lysis mediated by naturally occurring human cytotoxic cells. In addition to the similarity of naturally occurring human cytotoxic cells and murine NC cells in their specificity and lytic mechanism, naturally occurring human cytotoxic cells and murine NC cells are also similar in that their activity is both associated with a monocyte lineage and age independent. Taken together, these data indicate that humans express NC activity.

Adult↗
PubMed1987

Natural cytotoxic cells and tumor necrosis factor activate similar lytic mechanisms.

The lytic activity of natural cytotoxic (NC) cells has several characteristics which clearly distinguish it from other cell-mediated lytic activities and from most soluble cytolytic factors. An exception is the lytic activity mediated by tumor necrosis factor (TNF). In this paper, we report a detailed comparison of NC and TNF lysis of target cells which are used as prototype NC targets or TNF targets, and show that the two cytolytic activities have very similar, if not identical, lytic mechanisms. We present data showing that target cells which are NC-sensitive are also TNF-sensitive and that target cells which are NC-resistant are also TNF-resistant. Moreover, cells selected either in vivo or in vitro for NC resistance are selected for TNF resistance, and cells selected for TNF resistance are selected for NC resistance. The analysis of the kinetics of 51Cr release mediated by NC cells or by TNF show that both activities affect similar kinetics, in that there is no cell lysis for several hours after targets and effectors first interact. However, NC and TNF lytic activities can be distinguished. By using the cell lines 10ME or B/C-N as targets, it can be shown that whereas NC-mediated lysis is dependent on protein synthesis, TNF-mediated lysis is not. We also show that targets which are resistant to NC-mediated lysis because they express a protein synthesis-dependent resistance mechanism also require protein synthesis to resist TNF-mediated lysis, suggesting that the same resistance mechanism protects cells against both NC cells and TNF. Together, these data strongly support the hypothesis that NC cells and TNF activate the same lytic mechanism within target cells and that TNF may mediate the lytic activity of NC effector cells.

Animals↗
PubMed1987

Utilization of a consultation liaison psychiatry service in a general hospital.

This retrospective study was conducted in response to a need to evaluate the overall utilization rates of the psychiatric consultation liaison service by nonpsychiatric units within Howard University Hospital, which deals almost exclusively with a black, inner-city population. The study covers a three-year period (July 1982 to July 1985). During this time only 815 patients (2 percent) were referred for psychiatric evaluation out of the total number of hospital admissions (40,000 patients).Patient characteristics and general attitudes appear to have had a major role in this low ratio of referrals, particularly a lack of awareness and bias against psychiatry. This latter finding is in disparity with other published reports. Diagnostically, depression, organic mental disorders (acute), and substance abuse (mainly PCP) constituted the greater bulk of the patients seen by the consultation liaison psychiatry service. The review of a random sample of psychiatric inpatients (n = 100) revealed that in 50 percent of the cases there was a coexisting physical illness or abnormality.The role of mental health education and the liaison function needs to be emphasized. It is suggested that efforts should be directed toward a wider acceptance and utilization of consultation liaison psychiatry by primary care physicians in general hospitals. The factors listed by physicians and patients that may account for the observed underutilization of consultation liaison services are discussed. The results of 20 interviews and the reasons given by referring physicians as to whether or not they will seek consultation from the consultation liaison services are also reviewed.

District of Columbia↗
PubMed1986

The cloned cell line L10A2.J expresses natural cytotoxic activity.

The analysis of natural cytotoxicity (NC) has been hampered by the lack of cloned NC effectors. In studies reported here we show that the cloned cell line L10A2.J expresses properties similar to those of splenic NC effectors. L10A2.J cells lyse NC-sensitive targets, but do not lyse NC-resistant targets which are sensitive to lysis by natural killer (NK) or cytotoxic T lymphocytes. The mechanism by which L10A2.J cells lyse NC-sensitive targets is similar to the lytic mechanism of splenic NC effectors in that both result in the release of 51Cr from targets with a lag of 5-7 hr after effectors and targets are mixed. In addition, inhibition of protein synthesis during the in vitro assays of NC or L10A2.J lytic activity causes some NC-resistant targets to become sensitive to lysis by both NC and L10A2.J effectors. The only functional difference detected between L10A2.J and splenic NC effectors is in their recognition of targets. While L10A2.J and splenic NC effectors recognize many of the same targets (NC resistant and NC sensitive), L10A2.J, unlike splenic NC effectors, does not recognize the NK-sensitive cell line YAC-1.

Animals↗
PubMed1986

Dissociation of contact-noninhibition in vitro and tumorigenicity in vivo.

For cell lines, the correlation of the in vitro expression of contact-inhibition to the in vivo expression of the nontumorigenic phenotype, and the correlation of the expression of contact-noninhibition (i.e., focus formation) to the expression of the tumorigenic phenotype are commonly used as a means to identify, in vitro, cells which presumably have undergone malignant transformation such that, if tested, they would grow as tumors in vivo. In this report we show that while this correlation is true for contact-noninhibited transformants induced by benzo(a)pyrene (BP), a DNA mutating and demethylating agent, it is not true for contact-noninhibited transformants induced by 5-azacytidine (AZC), a DNA demethylating agent which does not have mutagenic activity. The in vitro treatment of a contact-inhibited cell line with 5-azacytidine (AZC) results in the expression of contact-noninhibited transformants, which, in vitro quantitatively and qualitatively similar to those induced by BP but unlike BP, treatment with AZC does not result in the in vivo expression of tumorigenicity.

Animals↗
PubMed1986

In vivo or in vitro selection for resistance to natural cytotoxic cell lysis selects for variants with increased tumorigenicity.

Experiments were designed to test the hypothesis that transformed cells that are NC sensitive must escape NC activity if they are to grow as tumors in normal individuals. NC-resistant variants were selected either in vivo or in vitro from NC-sensitive cell lines that grow as tumors in immunodeficient mice but not in syngeneic normal mice. The tumorigenicity of cloned NC-resistant variants was compared with the parental cell lines and to cell lines that went through the selection procedure, but after cloning remained NC sensitive. Cloned NC-resistant cell lines derived from tumors that developed in x-irradiated nude mice after the injection of an NC-sensitive cell line are tumorigenic in normal mice, whereas cloned NC-sensitive cell lines derived from the same tumors are unable to grow as tumors in normal mice. Similarly, six of seven NC-resistant cloned cell lines independently isolated after in vitro selection for NC-resistance are tumorigenic in normal mice, whereas cloned NC-sensitive cell lines isolated from the same in vitro selected populations are not tumorigenic in normal mice. Thus, either the in vivo or in vitro selection of NC-resistant cells selects for cells tumorigenic in normal mice; these findings, along with our previous observations that selection for cells tumorigenic in normal mice selects for NC resistance, provide compelling evidence that escape from NC activity is required before some transformed cells can grow as tumors in normal mice.

Animals↗
PubMed1985

Migration and the life cycle of households in southern Peru.

"This paper examines the relationships between migration and the life cyle of households in contexts where the economic activities of peasant families are increasingly diversified and where off-farm labor has come to form a vital part of subsistence strategies. Research from the department of Puno, southern Peru is used to explore the issues this raises including: (a) differences between externally induced economic differentiation and the life cycle dynamics of peasant households; (b) the differing migratory patterns of rich and poor households; and (c) the effects of migration on household labor supply and productive organization. The paper concludes by suggesting that for poor families, who exercise less control over the timing of the migratory process, migration may cause disruptive effects in [production], a reorientation of the household division of labor, and changes in reproductive decision-making."

Americas↗
PubMed1985

Analysis of immune surveillance of sequentially derived cell lines that differ in their tumorigenic potential.

The immune surveillance hypothesis suggests that cancer evolves as a multistage process. Further, it predicts that cells intermediate on the pathway to cancer are susceptible to host protective mechanisms, and only those variants that are able to escape the protective mechanisms are able to grow as tumors. We have isolated, as lineages, fibroblast lines that express phenotypes predicted by the surveillance hypothesis. The lineages were derived by treating nontransformed cells (N-cells) with chemical carcinogens and by isolating transformed variants in vitro. From the transformants that are tumorigenic in immune-depressed ATXFL mice but rejected by normal mice (I-cells), variants were selected in vivo that had escaped the rejection mechanism(s) and had grown as tumors in normal mice (C-cells). Thus lineages were established comprised of sequentially derived cell lines with the following phenotypes: nontransformed, transformed but susceptible to host protective mechanisms, transformed and resistant to host protective mechanisms (i.e., N----I----C). With the use of in vivo cross-protection experiments, two independently derived I-cell lines were shown to express non-cross-reactive antigens that are not expressed by the parental nontransformed N-cells (i.e., transformation-associated antigens). The transformation-associated antigens are expressed at an equivalent level on the cells that are susceptible to rejection (i.e., I-lines) and those that have escaped rejection (i.e., C-lines). In addition, although the transformation-associated antigens expressed by I-cells induce an effective immune response capable of rejecting both the I-line and C-line, the expression of these antigens on C-cells does not induce an effective immune response. The role of host defense mechanisms in the rejection of these chemically transformed I-cells and the possible mechanisms by which C-cells escape rejection are discussed.

Animals↗
PubMed1984

Training psychiatric staff to treat a multicultural patient population.

Cultural and linguistic barriers have long been problems in establishing an effective therapeutic alliance between patients and therapists from different cultural, ethnic, and racial backgrounds. The current emphasis on cultural psychiatry has stimulated the inclusion of culturally relevant material in the curricula of American psychiatric residency programs, such as the program at Howard University Hospital in Washington, D.C. After a preliminary study of foreign patients treated on the psychiatry service, the department of psychiatry established a program of seminars and didactic sessions intended to familiarize staff and trainees with cultural patterns of the largest groups of foreign students attending the university. The department also participated in a transcultural fellowship program for medical students sponsored by the American Psychiatric Association and the National Institute of Mental Health. After describing the programs, the authors briefly discuss such culturally related issues as foreign patients' return to their original language when they develop psychiatric illnesses.

Culture↗
PubMed1984

Biochemical abnormalities in psychiatric outpatients.

This research project was an outgrowth of the observations of the senior author over a period exceeding four decades of practice, teaching, and research as internist and psychiatrist, with primary emphasis on relationships between psyche and soma. Patients at the Outpatient Psychiatric Clinic of the Howard University Hospital, Washington, DC, were given thorough annual physical examinations and laboratory evaluations of blood and urine. The authors found a significantly high incidence of medical illnesses and abnormal laboratory findings not previously suspected. There was a significant and direct correlation between psychopathology as projected in the Lipman Personality Image Projection (LPIP) test and abnormal laboratory and physical findings. The results in this study concur with previous reports that so-called purely psychogenic stress symptoms may be related to unrecognized medical illnesses. These somatic illnesses may remain unrecognized for indefinite periods of time in the traditional psychiatric outpatient setting from which patients are often referred elsewhere for treatment of nonpsychiatric illness. Initial and periodic physical and laboratory examinations should be performed by psychiatrists trained to recognize nonpsychiatric diseases that often present with psychiatric symptoms. A thorough knowledge of the mind-body relationship is essential to the practice of modern psychiatry.

Aged↗
PubMed1983

Evidence that cytotoxic T cells and natural cytotoxic cells use different lytic mechanisms to lyse the same targets.

There is evidence that natural cytotoxic (NC) cells are in the T cell lineage. To lyse targets, cytotoxic T cells (TK) must recognize any of the myriad antigens plus syngeneic major histocompatibility complex (MHC) determinants. In spite of the evidence which indicates TK and NC are in the same lineage, NC cells can recognize few determinants (perhaps only one) and do not require recognition of MHC determinants. In addition to differences in the requirement for target recognition, in this report we show that TK cells and NC cells also use different lytic mechanisms to lyse the same targets. NC effectors initiate a lytic mechanism in NC-sensitive and NC-resistant targets. This lytic mechanism requires approximately 4 h before target lysis is apparent in NC-sensitive targets; it is inactivated by a protein synthesis-dependent counterlytic mechanism in NC-resistant targets. In contrast the TK lytic mechanism causes a rapid release of 51Cr from both NC-sensitive and NC-resistant targets and is not inhibited by the NC counterlytic mechanism present in NC-resistant cells. These findings lead to the conclusion that the mechanism used by NC cells to lyse targets is fundamentally different from that used by TK cells.

Animals↗
PubMed1983

An analysis of the sensitivity of somatic cell hybrids to natural killer cell- and natural cytotoxic cell-mediated lysis.

The analysis of the NK and NC sensitivity of somatic cell hybrids formed between parental cell lines that differ in their NK and NC sensitivity has shown the following. 1) The dominant expression of both NK and NC recognition determinants on target cells; 2) the dominant expression of two post-recognitive NC resistance mechanisms, one requiring protein synthesis and one being protein synthesis independent; and 3) the dominant expression of a post-recognitive NK resistance mechanism, which is protein synthesis independent. The post-recognitive protein synthesis-independent NC resistance mechanism confers no NK resistance and the post-recognitive NK resistance mechanism confers no NC resistance. Whether the post-recognitive protein synthesis-dependent NC resistance mechanism confers NK resistance remains open to question. The analysis of the hybrids indicates that transformed cells become sensitive to either NK- or NC-mediated lysis by losing their resistance to the lytic activity of these effector cells, and it appears that differentiation plays a role in determining whether NK or NC resistance will be lost upon transformation. A model is proposed in which the differentiation into a fibroblast associates the loss of NC resistance with transformation, whereas the differentiation into a lymphocyte associates the loss of NK resistance with transformation. Because the loss of NK resistance is not associated with the transformation of fibroblasts, they remain NK resistant, and because the transformation of lymphocytes is not associated with the loss of NC resistance, they remain NC resistant. This provides the basis for the target specificity exhibited by NK and NC effectors.

Animals↗
PubMed1983

The NIMH Diagnostic Interview Schedule: a test of its validity in a population of black adults.

This article examines the validity of the National Institute of Mental Health Diagnostic Interview Schedule (DIS) relative to three of its measures: alcoholism, depression, and schizophrenia when compared with the clinical interview. Preliminary results indicate that greater diagnostic agreement was observed for alcoholism and depression than for schizophrenia. Much of the disagreement between the DIS interview and the clinician's ratings regarding schizophrenia seems to have occurred in cases with a mixture of schizophrenic and depressive symptoms.

Adolescent↗
PubMed1982

In vivo surveillance of tumorigenic cells transformed in vitro.

Any theory of surveillance against cancer requires that cells susceptible to host protective mechanisms exist as intermediates on the pathway from normal to cancer. The failure to demonstrate a significant frequency of such intermediates as a result of chemical carcinogenesis has cast serious doubt on the validity of the surveillance hypothesis. Here we report the conditions in which such intermediates can be identified as the major class of transformed cells resulting from in vitro chemical carcinogenesis of a cloned fibroblastic cell line.

Benzopyrenes↗