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Featured researches published by Aaron Malkin.


Journal of the American Academy of Child and Adolescent Psychiatry | 1991

Nocturnal Cortisol, Thyroid Stimulating Hormone, and Growth Hormone Secretory Profiles in Depressed Adolescents

Stan Kutcher; Dina Malkin; Jay Silverberg; Peter Marton; Peter C. Williamson; Aaron Malkin; John P. Szalai; Marco Katic

Twelve depressed adolescents and 12 controls matched for age, sex, Tanner stage, time of menstrual cycle (females), weight, and time of year assessed were studied over 3 nights. Measurements for cortisol, thyroid stimulating hormone, and growth hormone were made on serum collected at 10 P.M., 12 midnight, 1 A.M., 2 A.M., 3 A.M., 4 A.M., and 6 A.M. in eight pairs and every 20 minutes from 8 P.M. to 7 A.M. in four pairs. Cortisol secretion did not significantly differentiate the groups. Thyroid stimulating hormone secretion was significantly elevated in the depressed group at one time point. Growth hormone secretion significantly differentiated the two groups at most time points, and the depressed adolescents significantly hypersecreted growth hormone (area under the curve). Implications for the diagnosis, etiology, and treatment of adolescent depression are discussed.


Cancer | 1978

Carcinoembryonic antigen in breast cancer.

Robert E. Myers; Donald J.A. Sutherland; Jw Meakin; John A. Kellen; Dina Malkin; Aaron Malkin

Carcinoembryonic antigen (CEA) levels were determined in 742 postoperative patients with breast cancer. Within this group the percentage of elevated (≥ 4.0 ng/ml) assays increased with UICC clinical stage and was 14.8% (12/81), 23.7% (27/114), 73.1% (190/260) and 20.0% (49/245) for stages I, 11, 111, IV and X (unstagable due to insufficient data) patients. We have now followed the above 482 stages I, II, III and X patients in whom CEA was performed ≤3 months after initial surgery at a time when there was no evidence of residual disease, for an average interval of 255 days from date of diagnosis. At present 16.2% (17/105) of patients with elevated CEA values compared to only 4.8% (18/377) of patients with normal values have developed recurrent disease (p < .0005). There is an association of elevation of CEA postoperatively with different clinical stages of breast cancer. Elevated CEA levels postoperatively are associated with an increased risk of development of recurrent disease in breast cancer patients.


Cancer | 1978

Carcinoembryonic antigen (CEA) and other tumor markers in ovarian and cervical cancer.

Aaron Malkin; John A. Kellen; Gordon M. Lickrish; Raymond S. Bush

Combinations of carcinoembryonic antigen (CEA), gamma glutamyl transpeptidase (GGT), pregnancy‐associated macroglobulin (PAM) and placenta‐like alkaline phosphatase (PLAP) were studied in groups of patients with ovarian and cervical cancer. In ovarian cancer, only CEA and PLAP levels appeared to reflect tumor burden and were complementary in detecting active disease. In cervical cancer, CEA and GGT reflected tumor burden, while PLAP showed just the reverse—the highest degree of positivity being present in minimal disease. PLAP positivity was even more pronounced in patients with cervical dysplasia and carcinoma in situ while CEA and GGT were negative. The data indicate that the use of marker combinations can improve our capacity to detect minimal disease and provide information regarding tumor biology that may not be available by studying individual markers or by other means. It remains to be determined whether the use of tumor markers can influence existing therapy sufficiently to alter the outcome in cancers which are notoriously difficult to treat.


AIDS | 1990

The effect of HIV-1 infection on the lipid fatty acid content in the membrane of cultured lymphocytes

Ami Klein; Louis Mercure; Paul Gordon; Barbara Bruser; Sharon Ramcharitar; Aaron Malkin; Mark A. Wainberg

Elevations in the levels of unsaturated fatty acids (FAs) in membrane lipids lead to an increase in cell membrane fluidity and may also be involved in cell fusion and death through the loss of normal membrane function and integrity. Since the infection of susceptible cells with HIV leads to cell fusion and subsequent loss of viability, the present study was undertaken to see whether HIV infection can alter the relative content of unsaturated FAs in the host cell membrane and to determine whether this change correlates with cell death. Peripheral lymphocytes (PBLs) of a healthy donor and two CD4+ cell lines were chosen: MT-4, which is killed following HIV infection, with significant cell death being observed 5 days postinfection, and H9 which is not killed. Measurements of FA content of the two cell lines and PBLs, either before or at 6, 24, and 48 h after infection, showed a significant rise in the concentration of unsaturated FAs followed by a drop in the concentration of saturated FAs in the MT-4 cell line. With regard to the H9 cell line similar results were obtained at 6 h from infection. However, at 24 and 48 h the concentrations of saturated FAs returned to preinfection levels while the concentrations of unsaturated FAs dropped to levels even lower than those obtained at zero time. No significant changes in FA composition were found with PBLs.


International Journal of Immunopharmacology | 1986

Alteration of lymphocyte reactivities by thyroid hormones

M. Ong; D.G. Malkin; Aaron Malkin

The effects of thyroid hormones (L-T4, L-T3 and rT3) on the proliferative response of rabbit peripheral blood lymphocytes to T-cell mitogens, PHA and Con A, and B cell specific goat anti-rabbit light chain antibodies (Anti-L) were investigated. It was observed that L-T4 potentiated the lymphocyte response to mitogens and Anti-L in a dose-dependent manner: 10(-9) M and 10(-8) M had no effect while 10(-7)-10(-5) M significantly enhanced the lymphocyte response. L-T3 (10(-11)-10(-8) M) had no effect on the lymphocyte response to PHA and Con A. At 10(-7) M, L-T3 inhibited the response to PHA but not Con A. L-T3 (10(-11)-10(-7) M) suppressed the lymphocyte response to Anti-L. The suppression was directly proportional to the L-T3 concentration. rT3 (10(-11)-10(-7) M) inhibited the proliferative response to PHA and Anti-L in a dose-related manner. Its effect on the lymphocyte response to Con A was stimulatory at 10(-11) M but inhibitory at higher concentrations (10(-8) and 10(-7) M). rT3 suppressed the enhancement by L-T4 of the lymphocyte response to the mitogens and Anti-L. The degree of suppression was proportional to its concentration. This data indicated that thyroid hormones can alter the reactivities of lymphocytes. The direction and magnitude of the alteration appear to depend on the concentration of a specific thyroid hormone encountered by the responding cells.


Journal of the American Academy of Child and Adolescent Psychiatry | 1988

Nocturnal Growth Hormone Secretion in Depressed Older Adolescents

Stan Kutcher; Peter Williamson; Jay Silverberg; Peter Marton; Dina Malkin; Aaron Malkin

Abstract A study of nocturnal growth hormone secretion in nine depressed adolescents and nine matched controls showed significantly greater secretory amplitudes at 2400 and 0100 hours in the depressed group. These differences were not related to sleep latency, total amount of slow wave sleep before the first REM period, nocturnal cortisol, or nocturnal free T4 levels. These findings suggest disturbed CNS regulation of nocturnal growth hormone in adolescent depressives.


Clinical and Experimental Immunology | 2008

NADP+ reduction by human lymphocytes.

A. Klein; A. W.‐L. Chan; B. U. Caplan; Aaron Malkin

The hexose monophosphate shunt (HMPS) is known to be responsible for the reduction of NADP+ by lymphocytes. We tried to find other enzymatic systems that might provide the lymphocytes with NADPH. By measuring the absorbance at 340 nm we noted that the addition of NADP+ to a preparation of disrupted lymphocytes resulted in the formation of NADPH at a rate of 4 nmol/106 cells per min. This phenomenon could not be changed by negative feedback inhibition of HMPS, and could not be attributed to the low concentration of glucose, glucose‐6‐phosphate (G‐6‐P) and isocitrate found in the cell preparation (NADP+ ‐dependent isocitratc dehydrogenase in addition to HMPS NADP+ reducing enzymes was found to be present in lymphocytes). Because of the activity of a NADP+ ‐dependent lactate dehydrogenase, pyruvate oxidized the NADPH as it was being formed. Here we demonstrate the presence of an unknown NADP+ reducer in lymphocytes which seems to play an additional role to HMPS in NADP+ reduction by lymphocytes. NADP+‐dependent lactate dehydrogenase may play a role in regulating the NADP+/NADPH ratio.


Surgical Neurology | 1982

The effect of acute spinal cord compression injury on thyroid function in the rat

Charles H. Tator; Richard H.C. van der Jagt; Aaron Malkin

The effect of acute spinal cord injury on thyroid function was studied in rats subjected to severe spinal cord compression at T1. Serum thyroxine (T4), effective thyroxine index (ETI), and thyroid stimulating hormone (TSH) were measured at 1 and 100 minutes at one, three, and seven days after laminectomy and spinal cord injury. Control animals were subjected to laminectomy only. T4 was decreased at 1 minute after laminectomy with or without spinal cord injury, though the animals with cord injury had a much more profound reduction. The effects on TSH at 1 minute were dramatically different: laminectomy alone caused an elevation of TSH, while spinal cord injury produced a marked decline. At the later time intervals both groups showed gradual normalization of T4 and TSH levels, and at seven days there were no significant differences between the groups. Thus, acute spinal cord compression injury produced a major alteration in thyroid function during the acute phase.


Enzyme | 1980

Aldolase isoenzyme patterns during human ontogeny and in lung, kidney and breast cancer.

John A. Kellen; Anna Chan; Brigitte Caplan; Aaron Malkin

Enzyme patterns characteristic of fetal tissue have been noted in some experimental tumor models, particularly in hepatomas. In this study we undertook to determine whether biochemical evidence of a similar reversion could be detected in tumors of other human organs. As marker, we chose to use the aldolase isoenzymes A, B and C, for which distinct adult and fetal tissue patterns have been described. Using monospecific antibodies, we determined the aldolase isoenzyme pattern in a variety of human organs ranging in age from 14 to 40 weeks of gestation, in the 2- to 3-month postnatal period and in adults. In addition, 19 breast cancers, 19 primary lung cancers and 8 kidney cancers were examined. Our studies on breast cancer revealed three apparently distinct groups -- one showing primarily the A isoenzyme type (6 cases), a second containing mainly A with considerable quantities of B and C isoenzymes (9 cases) and a third group (4 cases) which may contain a different isoenzyme altogether since the combined activity of the three known forms was less than 100% in each case. In lung cancer, fetal characteristics could be substantiated since in fetal and adult lung tissue, the isoenzyme pattern is almost identical; 3 out of 19 cases showed substantial quantities of the B isoenzyme. In kidney tumors, a reversion to the A form with an appreciable fraction of the C form was found, which is similar to the fetal pattern.


Clinical Biochemistry | 1985

The presence of glycosylated, biologically active chorionic gonadotropin in human liver.

Aaron Malkin; Marietta Reviczky; John A. Kellen

Whole extracts of normal human liver contain hCG-like material as determined by radioimmunoassay using antibodies to the beta subunit of the hormone. However, the extracts are biologically inactive, when analyzed by the in vitro rat Leydig cell assay for steroidogenesis. When subjected to Concanavalin-A-Sepharose chromatography, the radioimmunoassayable material was entirely lectin-bound. After elution with methyl-alpha-D-glucopyranoside, the lectin-bound fractions now displayed biological activity.

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Ami Klein

University of Toronto

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Ami Klein

University of Toronto

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