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Biomedical subjects

J Choate

Publications and source records attributed to J Choate.

7 recordsLinked to original sources
PubMed2001

Pregnancy and labor increase the capacity of human myometrial cells to secrete parathyroid hormone-related protein.

Parathyroid hormone-related protein (PTHrP), a oncofetal gene product possessing smooth muscle relaxant properties, has been found in rat and human uterine smooth muscle cells (USMC) where it is postulated to regulate myometrial tone and/or blood flow. Studies investigating the gestational regulation of PTHrP in human USMC have not been performed. This study was conducted to determine if pregnancy alters the capacity of USMC to secrete or respond to PTHrP. USMC cultures were established from 8 hysterectomy specimens (H) and 7 non-laboring (NP) and 5 laboring term pregnant uterine biopsies (LP). PTHrP secretion was measured at baseline and in response to TGF-beta1 using a immunoradiometric assay. The USMC response to PTHrP was assessed by incubating cultures with human (1-34)PTHrP and measuring cellular cAMP by radioimmunoassay. We found that cultures from the groups did not differ with respect to basal PTHrP secretion. TGF-beta1, on the other hand, produced dose-dependent increases in secreted PTHrP in each group such that LP>NP>H at 12 hrs and LP>NP and H 24 hrs. Maximal responses were found at 24 hrs in cells treated with 10 ng/ml TGF-beta1 (LP: 2034+/-366 vs NP: 1485+/-427; H: 1250+/-202 fmol/mg). Incubation of cultures with PTHrP produced dose-dependent increases in cAMP production, with 10(-7) M increasing levels by 64%. Neither pregnancy nor labor significantly affected the cAMP response. These findings indicate that the human myometrium has the capacity to increase PTHrP secretion during pregnancy and labor through a TGF-beta-dependent pathway. Such findings are consistent with a role of PTHrP in enhancing uterine blood flow.

Adult↗
PubMed1986

Pregnancy induced with menotropins in a woman with polycystic ovaries, endometrial hyperplasia, and adenocarcinoma.

A 31-year-old woman is described with PCOD associated with endometrial hyperplasia and well-differentiated adenocarcinoma. Conservative treatment with ovulation induction was pursued for a total of 3 1/2 years. After CC treatment failed to achieve conception, treatment with menotropins resulted in a twin pregnancy that aborted spontaneously and a singleton term pregnancy. Hysterectomy was performed 4 1/2 years after the initial diagnosis of well-differentiated endometrial adenocarcinoma was made. Histologic examination of the endometrium showed no progression of the disease. Ovulation induction of patients with polycystic ovaries and well-differentiated and noninvasive endometrial adenocarcinoma may be justified in properly selected cases.

Adenocarcinoma↗
PubMed1984

Platelet activation and cytoskeletal reorganization: high voltage electron microscopic examination of intact and Triton-extracted whole mounts.

The sequential changes in the three-dimensional organization of the filamentous components of human platelets following surface activation were investigated in whole-mount preparations. Examination of intact and Triton-extracted platelets by high voltage electron microscopy provides morphological evidence of increased polymerization of actin into the filamentous form and an increased organization of the cytoskeletal elements after activation. The structure of resting platelets consists of the circumferential band of microtubules and a small number of microfilaments randomly arranged throughout a dense cytoplasmic matrix. Increased spreading is accompanied by cytoskeletal reorganization resulting in the development of distinct ultrastructural zones including the peripheral web, the outer filamentous zone, the "trabecular-like" inner filamentous zone, and the granulomere . These zones are present only in well-spread platelets during the late stages of surface activation and are retained following Triton extraction. Extraction of the less stable cytoplasmic components provides additional information about the underlying structure and filament interactions within each zone.

Actins↗
PubMed1982

Occurrence of anti-retinal ganglion cell antibodies in patients with small cell carcinoma of the lung.

This report describes a patient with small-cell carcinoma of the lung associated with blindness. The serum of this patient was tested for immunoreactivity with retinal sections because there was no evidence of tumor metastasis to the central nervous system and because neuroendocrine cells of the lung share common antigens with retinal neurons. The immunoglobulins in the sera from this patient, from two other patients with small-cell carcinoma, from two patients with multiple sclerosis and from three controls were reacted with 8 micrometers thick sections of retina. Dog, cat and human retinal sections were used. Antihuman immunoglobulins that were conjugated to horseradish peroxidase were used as the second antibody to identify the cells which bound the patients' immunoglobulins. A high titer (1:500) antibody level against retinal ganglion cells was found in the patient with small-cell carcinoma and blindness; the antibody reaction was similar with retina from the three species. The large ganglion cells bound the immunoglobulins of the patients with small-cell carcinoma and blindness while the immunoglobulins from the control and multiple sclerosis subjects did not bind these cells selectively at high dilutions. It remains to be shown whether these antibodies have an etiologic significance in the development of blindness.

Aged↗
PubMedDate not supplied

Changes in acid precipitation-related water chemistry of lakes from southwestern New Brunswick, Canada, 1986-2001.

Between 1986 and 2001, thirty-nine lakes in southwestern New Brunswick in Atlantic Canada were surveyed for acid precipitation-related water quality changes. Most of the study lakes are located on granite bedrock and represent the most acid sensitive lakes in the province. Between 1987 and 1992, hydrogen ion deposition to the lake study area averaged 452 eq ha(-1) yr(-1), compared to 338 eq ha(-1) yr(-1) between 1993 and 2000, a 25% reduction. The lake chemistry data were evaluated by dividing the lakes into four clusters for each survey year based on their acid neutralizing capacity. Twenty percent of the lakes (cluster IV) had an average ANC of 40 microeq L(-1) or greater and maintained an average pH of greater than 6 over the duration of the study period. A pH of 6 or greater is considered a healthy benchmark for maintaining biodiversity. The remaining 31 lakes (clusters I to III) had an average ANC of less than 40 microeq L(-1) and maintained an average pH of less than 6. Other lake chemistry changes included a general decline in lake sulphate and colour over the duration of the survey period, followed by more recent improvements in calcium ion, pH and ANC, and notably higher but declining aluminum levels in lower ANC and pH lakes. Nitrate accounted for 37% of the acid deposition to the study area, however it was not detectable in the lakes. Although acid deposition has declined and these lakes are beginning to show signs of acid recovery, 80% of the study lakes remain acid sensitive having little buffering capacity with low calcium, pH and ANC.

Acid Rain↗