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Biomedical subjects

N Parikh

Publications and source records attributed to N Parikh.

At least 19 recordsLinked to original sources
PubMed2000

Emergency department use in New York City: a substitute for primary care?

For the uninsured and many low-income people, hospital emergency departments (EDs) are a crucial entryway to the health care system. New York City's uninsured-27 percent of the nonelderly population in 1998, up from 20 percent in 1990-rely heavily on the ED for their medical care. Residents who regularly get their health care at an ED do not have regular doctors or continuity in their care, use costlier services, and often receive treatment that could have been avoided. Low-income New Yorkers may be depending on emergency department care even more as Medicaid enrollment declines and physician reimbursement rates are cut. This Issue Brief describes patterns of ED use through-out New York City and discusses some of the ways to improve the availability of primary care services and reduce ED dependency.

Emergency Service, Hospital↗
PubMed1998

Stimulation of the protein tyrosine kinase c-Yes but not c-Src by neurotrophins in human brain-metastatic melanoma cells.

The c-Yes proto-oncogene (pp62c-Yes) encodes a non-receptor-type protein tyrosine kinase (NRPTK) of the Src family. c-Yes activities and protein levels are elevated in human melanoma and melanocyte cell lines. Because the neurotrophins (NT) are important in the progression of melanoma to the brain-metastatic phenotype, we determined whether NT stimulate c-Yes activity in human MeWo melanoma cells and two variant sublines with opposite metastatic capabilities, 3 S 5 and 70W. The highly brain-metastatic 70W subline had an intrinsically higher c-Yes activity than parental MeWo or poorly metastatic 3 S 5 cells. c-Yes kinase was further induced by the prototypic human NT, nerve growth factor (NGF) in a dose and time-dependent manner. In contrast, c-Src activity (pp60-Src) was similar in all these cells and unaffected by NGF exposure. Additionally, human NGF and neurotrophin-3 stimulated c-Yes in brain-metastatic 70W cells. The magnitude of c-Yes activation correlated with the degree of invasion of 70 W cells following incubation of these neurotrophins. To further examine NT stimulation of c-Yes in melanoma cells, three additional cell lines were examined. Metastatic TXM-13 and TXM-18 increased c-Yes activity in response to NGF. In contrast, no increase was observed in low-metastatic TXM-40 cells. Together, these data suggest that altered c-Yes expression may play a role in the malignant progression of the human melanocyte towards the brain-metastatic phenotype and that NT enhance the activity of c-Yes in signaling penetration into the matrix of NT-rich stromal microenvironments such as the brain.

Brain Neoplasms↗
PubMed1992

Failure of rectal ornithine decarboxylase to identify adenomatous polyp status.

Rectal mucosal ornithine decarboxylase (ODC) activity has been reported to distinguish between patients with and without adenomatous polyps (AP). In the present investigation, ODC activity has been measured in 28 patients with AP and 34 patients without AP. To assess the intraindividual variation in ODC activity, repeat biopsies were performed on 11 patients. In addition, the effect of postbiopsy sample handling was investigated by storage of samples on either dry or wet ice during transport to the laboratory. The mean rectal mucosal ODC activity in patients with AP was 196.0 +/- 195.5, whereas that in AP negative patients was 182.2 +/- 320.5. The rectal mucosal ODC activity in patients with colorectal cancer was 388.2 +/- 581. Repeat samples in individuals were generally within the same range as the original samples. The method of sample transport did not significantly affect the level of ODC measured in a particular biopsy. Because of high variability in rectal mucosal ODC activity within the population, there was wide overlap in ODC values between those patients with and without AP in an unselected general population. Thus, the measurement of flat rectal mucosal ODC activity is not a good predictor of the presence or absence of AP. Additional studies of the factors affecting mucosal ODC activity are necessary before the potential clinical utility of the method can be realized in the general population.

Aged↗
PubMed1992

Severity of disability and duration of disease in rheumatoid arthritis.

A longitudinal sample of patients with rheumatoid arthritis (RA) from Santa Clara County, CA was analyzed. Severity was measured with the Disability Index from the Health Assessment Questionnaire (HAQ). First, 6 cohorts were created of women and men with 0 to 10, > 10 to 20, and > 20 years of duration of illness in 1981. Experiences of the 6 cohorts were studied from 1981 to 1989. For both sexes, and both samples which alternately included and excluded the deceased, persons with > 20 years of duration experienced faster deterioration than those with < 20 years. Second, multiple regression models were estimated which treated the Disability Index as the dependent variable. In the regression models, the Disability Index worsened more quickly for women than men, for persons with few rather than many years of education, and for older than younger persons. Regression models which excluded an intercept term suggested a unique "S" shaped curve that described the Disability Index and duration relation.

Adult↗
PubMed1990

Thymosin alpha 1 enhancement of human lymphocyte proliferation is not mediated by prostaglandin E2.

Prostaglandins of the E series have been implicated as possible mediators of thymosin alpha 1 (TA-1) effect on mitogen stimulated lymphoproliferation. In the present study human peripheral blood mononuclear cells were stimulated with concanavalin A in the presence of TA-1, prostaglandin E2 and indomethacin individually, or in combination. Both TA-1 and indomethacin significantly enhanced the proliferative response over that seen with mitogen alone (less than 0.001). The magnitude of enhancement observed with indomethacin (20 microM) was considerably less than that of TA-1 and it was abolished with prostaglandin E2. The combination of indomethacin and TA-1 did not alter TA-1 effect and prostaglandin E2 (up to 250 ng/ml) did not abolish thymosin effect. These results suggest that TA-1 and prostaglandin E2 have opposite effects and that thymosin enhancement of mitogen induced proliferation is not mediated by prostaglandin E2.

Concanavalin A↗
PubMed1987

Epstein-Barr virus-transformed B-cell line (DV-1) derived from bone marrow of a patient with severe combined immunodeficiency and immunoblastic lymphoma.

An Epstein-Barr virus-transformed B-cell line derived from a patient with severe combined immunodeficiency who died of a lymphoreticular malignancy has been characterized. The line derived from bone marrow cultures and designated DV-1 shows surface and cytoplasmic IgM and staining with fluorescent monoclonal antibodies against immunoglobulin heavy and light chains mu, delta, and kappa, Dr, and several other B-cell surface antigens. DV-1 secretes IgM kappa and demonstrates monoclonality on analysis of immunoglobulin heavy and light chain gene rearrangement patterns. Incubation with either phytohemagglutinin or pokeweed mitogen failed to cause significant stimulation of proliferation of DV-1 and another EBV-transformed B-cell line derived from an immunologically normal host (LA-350), whereas incubation with Staphylococcus aureus Cowan strain 1 led to significant inhibition of DV-1 and LA-350. Rabbit IgG antibody specific for human immunoglobulin mu-chains produced a dose dependent stimulation of both lines. The responses of DV-1 and LA-350 to mitogens and anti-mu were not as high as those of normal peripheral blood lymphocytes. This spontaneously derived Epstein-Barr virus-transformed B-cell line from a patient with severe combined immunodeficiency demonstrated functional characteristics similar to a B-cell line derived from an immune competent host. While these cells spontaneously incorporate 200 times more thymidine than normal resting peripheral blood lymphocytes, they retain their ability to be modulated by antiimmunoglobulin, and staphylococcal Cowan strain 1, but are unresponsive to the effects of B-cell growth factor.

B-Lymphocytes↗
PubMed1986

Monoclonal anti-actin antibody recognizes a surface molecule on normal and transformed human B lymphocytes: expression varies with phase of cell cycle.

A monoclonal anti-actin antibody, 2C9, was used to study the distribution of an actin-like cell-surface antigen (hereafter termed actin) on a lymphoblastoid cell line LA350 and on human peripheral blood lymphocytes. It was determined that 8-40% of LA350 cells and 3-15% of peripheral blood lymphocytes from healthy donors stain specifically with 2C9, almost exclusively on IgM-positive cells. Treatment of cells with 2C9 prior to incubation caused cell-surface actin to first patch and then to cap. Treatment of cells with nonspecific protease caused a loss of surface actin, with reexpression of the marker after 8-12 hr. The expression of LA350 surface actin also increased with DNA synthesis and was demonstrated to be maximal during late G1/early S phase. Thus, this antigen may be a sensitive marker for activated lymphocytes. These studies contribute to our understanding of the expression and distribution of actin-like membrane proteins that may participate in regulatory signals mediated by anti-actin antibody.

Actins↗
PubMed1986

Malignant osteoclast-like giant cell tumor associated with a uterine leiomyosarcoma.

An unusual case of osteoclast-like giant cell tumor associated with a leiomyosarcoma of the uterus is described. The mononuclear cell component of the giant cell tumor was cytologically malignant and the giant cell tumor was present in a biopsy of vaginal recurrence. The patient expired 17 months after diagnosis with extensive tumor despite surgical and radiation treatment. This is the first report of malignant osteoclast-like giant cell tumor associated with a uterine leiomyosarcoma and only the third report of osteoclast-like giant cell tumor in the uterus.

Aged↗
PubMed1985

Mitogen-like monoclonal anti-actin antibodies.

Monoclonal antibodies (IgM kappa) have been produced to actin isolated electrophoretically from L cell extracts. These monoclonal anti-actin antibodies bind to intact L cells and modulate DNA synthesis and cell proliferation, much like affinity-purified polyclonal rabbit antibody to the same Mr 42,000 actin. In addition, monoclonal antibodies specific for actin from Entamoeba histolytica also bound to and modulated the growth of L cells. A monoclonal antibody directed against a neuroblastoma surface antigen did not produce stimulation of L cells, and the binding activity of anti-actin monoclonal antibody to L cells was removed by absorption with actin covalently coupled to Sepharose. These observations demonstrate the specificity of interaction between the anti-actin monoclonal antibodies and the surface of intact L cells. We conclude that a surface actin-like molecule on the L cell, when bound by specific monoclonal antibody, initiates a stimulatory signal which results in enhanced cellular metabolism.

Absorption↗
PubMed1983

Atrial flutter secondary to hypokalemia.

Electrophysiologic studies support significant hypokalemia as a cause of atrial flutter in a patient without manifest heart disease. Atrial flutter, reproducibly initiated and terminated by rapid atrial pacing during hypokalemia, was not inducible after potassium correction. In an individual with existing atrial conduction disease, hypokalemia may generate both non-uniform atrial refractoriness and atrial premature beats, and it may facilitate the development of atrial flutter as a re-entrant arrhythmia.

Aged↗
PubMed1983

A comparative study of centbucridine and lidocaine in dental extraction.

A randomized double-blind study comparing the efficacy and tolerability of centbucridine (0.5%) with those of lidocaine (2%) as an anaesthetic agent was conducted in the dental outpatient department on patients attending for dental extraction. One hundred and twenty patients were studied. The degree of analgesia attained with centbucridine compared well with that obtained with lidocaine. The compound was well tolerated with no significant changes in the cardiovascular parameters and no serious side-effects.

Adolescent↗