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Biomedical subjects

M Ritter

Publications and source records attributed to M Ritter.

At least 235 records · Page 13Linked to original sources
PubMed1978

Functional and dysfunctional uterine bleeding.

The patient who comes to the physician with abnormal bleeding represents an enormous responsibility. The various causative factors represent defects in numerous physiologic systems. The diagnosis of DUB still requires further investigation of the hormonal imbalance. Only when specific causes are known can the treatment be tailored to the particular patient. Recent scientific advances regarding possible cellular mechanisms for DUB make it mandatory that the primary physician be aware of available tests that may indicate the relative appropriateness of and prognosis for a particular therapy. The treatment is substitutional. If progesterone is missing, therefore,the treatment should replace it. Progesterone may be obtained endogenously by ovulation induction or exogenously by oral or parenteral progestogens.

Adolescent↗
PubMed1975

Mathematical analysis of energy regulatory pattens of normal and diabetic rats.

Analysis of feeding patterns indicated that diabetic (alloxan) hyperphagia is characterized by doubling of meal sizes with no change in feeding frequency. Correlation of meal sizes and intermeal intervals did not provide any systematic relationships for either normal or diabetic rats. When equations of the general form Y = A + Bcos (X) were fit to successive satiety ratios (postmeal interval/meal size), the diabetic rats showed significantly lower A coefficients, reflecting a lower average level of satiety, as well as significantly lower B coefficients, reflecting less systematic variability in the satiating value of food around the average level. It is concluded that the major regulatory deficit in diabetic animals is a chronic reduction in the long-term signal of body nutrient repletion.

Animals↗
PubMedDate not supplied

Circumvention of the tumor membrane barrier to WR-2721 absorption by reduction of drug hydrophilicity.

In attempting to account for the ability of most solid tumors to restrict the absorption of WR-2721, aminopropyl-aminoethylphosphorothioate, we examined a number of drug characteristics which might allow for this restriction, and observed that drug hydrophilicity was a major contributing factor. When the highly hydrophilic WR-2721 was dephosphorylated, the drug became less hydrophilic and could readily cross tumor cell membranes. In addition, conventional radioprotectants, such as cysteine and mercaptoethylamine, were shown to be less hydrophilic than WR-2721 and also to cross tumor membranes readily. Therefore, drug hydrophilicity would appear to be the factor underlying the ability of WR-2721 to selectively protect normal tissues while most other protectors alter the radiation resistance of normal and tumor tissue alike. A red blood cell model for studying this problem in greater detail is described.

Absorption↗
PubMedDate not supplied

Coronary pseudoaneurysm: diagnosis by intravascular ultrasonography.

A pseudoaneurysm after percutaneous coronary angioplasty (PTCA) of the left anterior descending coronary artery is reported in a 52-year-old woman who underwent PTCA for exertional angina and a significant isolated stenosis of the left anterior descending coronary artery. Intravascular ultrasonography during repeat coronary angiography clearly identified a localized coronary dilation at the PTCA site in conventional coronary angiography as a pseudoaneurysm that was confirmed during surgery.

Aneurysm, False↗
PubMedDate not supplied

Preservation of fertility and ovarian function and minimizing chemotherapy-induced gonadotoxicity in young women.

BACKGROUND: After the improved long-term survival in young women with lymphoma and leukemia undergoing chemotherapy, the preservation of future fertility has been the focus of recent interest. AREAS OF REVIEW: Three major topics are reviewed. They include the following: (1) the role of chemotherapy in the treatment of malignant and nonmalignant disease in young women, the types of chemotherapy and their gonadal effects (differing between ovaries and testes) in both human and other species, and the reasons for differences in the outcomes of various studies; (2) the human experience with GnRH-agonist therapy for minimizing chemotherapy-associated gonadotoxicity; and (3) inhibin measurements in young women treated by chemotherapy and in perimenopausal patients and those with impending premature ovarian failure (POF). Whereas egg retrieval for in vitro fertilization (IVF) and embryo cryopreservation is a valid assisted reproductive technology (ART) for married couples, it may be unacceptable for the young single woman. The investigational endeavors of ovarian cryopreservation awaits the clinical experience of in vitro maturation of thawed primordial follicles, their IVF, and embryo transfer. Although promising, this experience is not yet available. Moreover, the risk of possible reimplantation of malignant stem cells with the thawed cryopreserved ovary has been raised after animal observations. Therefore, until these innovative endeavors prove successful, and in parallel with them, an attempt was made to minimize the gonadotoxic effect of chemotherapy by the cotreatment with a GnRH agonistic analogue (GnRH-a) to induce a temporary prepubertal milieu, because prepubertal ovaries were found more resistant to alkylating agents' effect than the ovaries of older women. To characterize the correlation with ovarian function after gonadotoxic chemotherapy for Hodgkin or non-Hodgkin lymphoma in young women, the immunoreactive inhibin-A concentrations in the sera of these patients were measured before, during, and after the gonadotoxic chemotherapy. CONCLUSIONS: The GnRH-a cotreatment should be considered in every woman in the reproductive age receiving chemotherapy, in addition to ART and the investigational attempts of ovarian cryopreservation for future in vitro maturation or reimplantation. If these preliminary data are confirmed in a larger group of patients, inhibin-A concentrations may serve as a prognostic factor for predicting the resumption of ovarian function in addition to the levels of FSH, LH, and estradiol.

Antineoplastic Agents↗