Differences in the absorption, metabolism and biliary excretion of a diastereomeric pair of alphavbeta3-antagonists in rat: limited role of P-glycoprotein.

1. The study investigated mechanisms underlying the pharmacokinetic differences of two zwitterionic diastereomers ((3S)-3-[(3R or 3S)-2-oxo-3-[3-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)propyl]pyrrolidin-1-yl]-3-quinolin-3-ylpropanoic acid) with different lipophilicities using a combination of in vivo and in vitro approaches. 2. In rat, both isomers possessed comparable plasma clearances (CL). However, the more lipophilic diastereomer I exhibited a higher metabolic clearance (>2-fold higher than II), whereas the hydrophilic zwitterion II exhibited a higher biliary clearance (approximately 5-fold higher than I). Following oral administration, the bioavailability (F) of I (17%) was much higher than that of II (1%). 3. Consistent with these in vivo observations and the expectation based on their lipophilicity differences, the metabolism in rat liver microsomes was faster and the permeability in Caco-2 and LLC-PK1 cells and in situ rat intestinal loop was better for I than for II. 4. Only the absorption of the more lipophilic diastereomer I was subjected to an efflux system in the Caco-2 and in situ rat intestinal loop models. I was a good substrate for P-glycoprotein (P-gp) in both the human MDR1 and mouse mdr1a transfected cell lines, and in the wild-type mdr1a (-/-) mouse when compared with the P-gp-deficient mdr1a (-/-) mouse. Concomitant administration of I with verapamil in rat caused significant increases in oral AUC, F and Cmax of I without affecting its CL, further supporting the effect of P-gp in limiting the intestinal absorption of I in vivo in this animal model. 5. Since the findings that the lipophilic diastereomer I, but not II, was a good P-gp substrate were not in line with the observations that I was excreted to bile much slower than II and that I was absorbed better than II, the results suggested that P-gp played a minor role to the observed differences in the biliary excretion and intestinal absorption of the diastereomers I and II in rat.

In vitro and in vivo evaluation of dihydropyrimidinone C-5 amides as potent and selective alpha(1A) receptor antagonists for the treatment of benign prostatic hyperplasia.

alpha(1) Adrenergic receptors mediate both vascular and lower urinary tract tone, and alpha(1) receptor antagonists such as terazosin (1b) are used to treat both hypertension and benign prostatic hyperplasia (BPH). Recently, three different subtypes of this receptor have been identified, with the alpha(1A) receptor being most prevalent in lower urinary tract tissue. This paper explores 4-aryldihydropyrimidinones attached to an aminopropyl-4-arylpiperidine via a C-5 amide as selective alpha(1A) receptor subtype antagonists. In receptor binding assays, these types of compounds generally display K(i) values for the alpha(1a) receptor subtype <1 nM while being greater than 100-fold selective versus the alpha(1b) and alpha(1d) receptor subtypes. Many of these compounds were also evaluated in vivo and found to be more potent than terazosin in both a rat model of prostate tone and a dog model of intra-urethral pressure without significantly affecting blood pressure. While many of the compounds tested displayed poor pharmacokinetics, compound 48 was found to have adequate bioavailability (>20%) and half-life (>6 h) in both rats and dogs. Due to its selectivity for the alpha(1a) over the alpha(1b) and alpha(1d) receptors as well as its favorable pharmacokinetic profile, 48 has the potential to relieve the symptoms of BPH without eliciting effects on the cardiovascular system.

Further evidence of a decorin-collagen interaction in the disruption of cervical collagen fibers during rat gestation.

OBJECTIVE: Our purpose was to determine the histologic distribution and expression of decorin in rat cervix throughout the course of rat gestation and to correlate the findings with the known progression of collagen fiber disruption and cellular turnover in this tissue. STUDY DESIGN: Cervices from pregnant animals at 5, 11, 18, and 21 days were studied. A proteoglycan of low molecular weight, decorin, was detected by sensitive and specific immunohistochemical analysis with a biotin-avidin horseradish peroxidase method. RESULTS: Decorin was not detected on day 5. By day 11 moderate decorin staining was detected in the subepithelial layer and in the deep stroma. Decorin staining progressed to a strong expression in the subepithelial layer and to a moderate expression in the deep stroma on day 18. On day 21 (term in rat) the staining was fairly homogeneous throughout the connective tissue stroma. CONCLUSION: These findings clearly demonstrate that decorin expression increased progressively throughout pregnancy and are consistent with the hypothesis that an excess of decorin near term is capable of initiating a decorin-collagen interaction that leads to collagen fibril disruption and decreased cervical tensile strength.

Cell death and proliferation and its relation to collagen degradation in uterine involution of rat.

Collagen concentration, procollagenase localization, and their association with cell proliferation and apoptosis during postpartum involution, were investigated biochemically and histochemically in postpartum day 1, 3, 5, and 7 rat uterine tissues. In control animals, uterine wet weight, soluble protein, and collagen decreased rapidly during days 1 to 3 postpartum, and the DNA concentration in the uterine horn rapidly decreased, as noted by others. Simultaneously, both apoptosis and cell proliferation were observed in these tissues. These processes were highest in smooth muscle cells on day 3 postpartum. Procollagenase was found in the cell cytoplasm through days 1 to 3 postpartum, was highest on the third day postpartum, and appeared to gradually diminish by day 5 postpartum. Disorganization of collagen fibers was observed, under polarized microscopy by a strong birefringence of collagen fibers of the circular smooth muscle cell layers. However, this disorganization of the uterine collagen diminished progressively from day 3 to day 7. Treatment with estradiol or a combination of estradiol and progesterone suppressed cellular turnover and attenuated the changes in DNA, total amino acids, and collagen on day 3 postpartum. In this study, cellular turnover and biochemical and morphological changes appeared to be closely associated. Gonadal steroid hormones appear to influence these changes and retard uterine involution. This study suggests that a dynamic turnover of the cellular population takes place during uterine involution. It is possible that other factors, in addition to steroid hormones, contribute to uterine involution. It is to be postulated that these factors either are themselves decreased or, alternatively, may increase the inhibition of other unknown factors by an indirect mechanism.

Proliferation and apoptosis of fibroblasts and smooth muscle cells in rat uterine cervix throughout gestation and the effect of the antiprogesterone onapristone.

OBJECTIVE: The purpose of this study was to determine the relative percentages of apoptosis and proliferation in fibroblasts and cervical smooth muscles throughout gestation and the effect of an antiprogesterone on these processes. STUDY DESIGN: Rats were studied at days 5, 15, 18, and 21 and immediately postpartum (day 22). Apoptosis and proliferation as detected by specific immunohistochemistry quantitative morphometric analysis was performed. Onapristone, an antiprogesterone, was used to study effects of hormonal change on these processes in 16- and 19-day timed-pregnant rats. RESULTS: Proliferation of fibroblasts and smooth muscle cells was highest in early pregnancy and decreased progressively, whereas apoptosis increased progressively in later pregnancy. Onapristone inhibited apoptosis. CONCLUSION: Changes in cervical cellular turnover are initiated early in gestation and are under hormonal influence. Antiprogesterone inhibits cell death at days 16 and 19 of gestation.

Reaction of residents to a teaching collaborative practice.

Using the team concept, certified nurse-midwives, nurse practitioners, and physician assistants help educate physicians in an obstetrics and gynecology residency program and help to create a balance between education and service. This program is well received by the physicians in graduate medical education, and the majority indicate they will work within a collaborative model of practice.

Medicaid managed care partnerships to improve perinatal outcomes.

New York State's Prenatal Care Assistance Program, and enhanced care program based on public health principles, is in the process of being transformed into Medicaid managed care. The program described in this article, namely, a Medicaid managed care health maintenance organization and its interaction with one hospital's care of women, especially pregnant women, serves to illustrate how traditional public health values and managed care principles may be linked. This linkage is a starting point to developing a community's involvement in its own health, although it is too early from our experience to note a lasting effect on improved pregnancy outcomes.

Analyzing strategies for developing a prenatal health care outreach program to reduce social and cultural barriers.

Beginning in March, 1994, a multi-cultural, interdisciplinary team of health care providers at Rochester General Hospital in Rochester, New York, planned and implemented a prenatal outreach program in partnership with the Rochester YWCA. The purpose of the project is to increase access to obstetric and gynecological services for low-income African-Americans, Hispanic, and white women. The processes involved in developing an outreach intervention program, Opening Doors, are described and the conflicts that surfaced during the initial stages of program development are analyzed. The problems which occurred can be attributed to role boundary conflict and differences in philosophy regarding ethnicity and health behavior. Through interviews with the anthropologist on the management team and some changes in the overall structure of the program administration, resolution of the conflicts became possible.

Learning from the community about barriers to health care.

One of the major challenges facing obstetrician-gynecologists, especially those serving populations that are diverse in culture and circumstances, is to identify and address the barriers that keep women from seeking timely preventive and prenatal health care. The Department of Obstetrics and Gynecology at Rochester General Hospital held a community focus groups to learn more about women's attitudes toward health care. In addition to economic issues, such as lack of insurance and an inability to pay, the organizers found that many of the factors that prevent or discourage women from seeking health care involve issues of communication and understanding. Many women wanted what they perceived to be additional services. In reality, many of the things desired involved changes in doctor-patient interactions rather than the addition of any new service, and could be addressed with relative ease and minimal cost. Providing staff members with training in cultural sensitivity and encouraging them to develop a real awareness of patient circumstances are first steps that can lead to better communication between provider and patient and to the development of mutual trust. Other factors, such as the fear of incarceration or of losing one's children if health care is sought, present more serious challenges. Providers of care to high-risk, impoverished populations need to develop strong links to mental health, substance abuse, and family preservation services that allow them to intervene with troubled women and their families with services that are alternatives to incarceration and punitive actions.

Collagen changes in rat cervix in pregnancy--polarized light microscopic and electron microscopic studies.

The structural arrangement of collagen fibers in cervical ripening was studied in normal pregnant rats by picrosirius red staining and polarized light microscopy. The macromolecular arrangement of collagen fibers in the cervices of nonpregnant controls and in firm and rigid cervices of rats in early pregnancy (1-10 days of gestation) were optically anisotropic and had birefringence and a positive sign of elongation when examined by polarized light microscopy. The findings indicated that the structure of these collagen fibers was assembled from well-packed parallel collagen molecules. The direction of fibrous formation was arranged with regularity. In contrast, most of the collagen fibers in the soft cervices were optically isotropic. The fibers were fragmented and had a structure with discontinuous birefringence. Disarray and disorientation of the collagen fibers was found in the soft cervices. These collagen fibers changed their direction of formation. The disorganization of these collagen fibers might have a major impact on weakening the tensile strength of the cervix. Thus, we conclude that the processes of rearrangement of collagen fibers might be an important process in the cervical ripening. Electron microscopic studies suggest that in the focal hydrolytic processes of collagen and other matrix components degradation by lysosomal and phagosomal vesicles were associated with atrophic smooth muscle cells and fibroblasts of the cervices. Hydrolases released from lysosomes from these apoptotic cells may presumably be one of the processes in the remodeling of collagen structure.

Epidemiology of uterine leiomyomas. With an etiologic hypothesis.

OBJECTIVE: The few previous epidemiologic studies of uterine myomas have relied on clinical evaluation to select controls, but we previously showed that myomas may be present in more than 75% of such uteri. STUDY DESIGN: We therefore attempted to evaluate risk factors using age-matched controls whose uteri were serially sectioned to exclude the presence of myomas. RESULTS: The small study size precluded a meaningful evaluation of most parameters but tended to confirm the negative association of myomas with cigarette smoking (P = .07). CONCLUSION: Using monoclonal smooth muscle proliferation in human atherosclerotic plaques as a model, we suggest that excessive injury to and repair of the endometrial lining of the uterus may promote monoclonal expansion of smooth muscle cell populations in the uterine wall (i.e., myomas). This theory is largely compatible with the estrogen hypothesis, but fundamental principles of tumorigenesis and previous epidemiologic data on myomas suggest that nutritional factors should be scrutinized as possible initiators (DNA-damaging substances) in the pathogenesis of uterine myomas.

Anatomy and physiology of cervical ripening.

The uterine cervix is a unique organ composed predominately of the extracellular matrix proteins, collagen, elastin, and glycosaminoglycans. During pregnancy and labor, this organ is metabolically active, which is rare in adult tissue. The metabolism is under reproductive hormonal control and is more complex than previously appreciated. Smooth muscle cells, which comprise 10-15% of cervical tissue, undergo programmed cell death and play a role in cervical softening. Apoptosis is a genetically timed event and could explain the species-specific length of gestation. Further research in the next several years will reveal more completely the exciting process of cervical ripening. Only when this phenomenon is understood will rational therapy for preterm labor and post-term pregnancy with an unripe cervix be available. Specific defects in cervical ripening will then be diagnosed and treated. For example, if apoptosis is shown to play an important role in the process of cervical ripening, it could be inhibited. Conversely, it could be induced in the unripe cervix. If we would look for it, we would find that it is probably occurring today in the clinical use of cervical ripening agents. The most important contributor to cervical softening, however, is a rearrangement and realignment of the collagen, elastin, and smooth muscle cells, which occurs due to mechanical forces and to a rearrangement of the collagen that occurs as the content of glycosaminoglycans varies in the cervix with time. One form of dermatan sulfate, decorin, may help to separate the collagen fibrils and then open them up. This rearrangement also involves fiber shortening below the critical length for tensile strength, allowing for extensibility of the cervix. Because of its orientation in the cervix, elastin contributes to the ratchet-like mechanism of dilatation. Finally, the cervix undergoes change in two phases--softening, which involves collagen realignment, and dilatation. The proteolytic enzymes in the cervix degrade cross-linked, newly synthesized collagen, and they help activate other enzymes in a cascade. However, the predominate anatomic and physiologic change in ripening is the rearrangement of collagen.

Use of everted intestinal rings for in vitro examination of oral absorption potential.

The ability to predict in vivo oral absorption potential based on ex vivo screening in an everted intestinal ring model was examined. In vitro drug accumulation in cross sectional rings of everted rat jejunum was determined with 12 compounds whose in vivo absorptions (as distinct from bioavailabilities) are well characterized. The compounds examined ranged from well- to poorly-absorbed and included compounds absorbed by active and passive mechanisms. The effects of drug concentration, pH, cosolvents, and tissue origin site on drug accumulation were determined. Light microscopic observation indicated that the mucosal tissue remained intact up to 3 h after the intestine was excised. Accumulations of two nonabsorbable markers were also determined as measures of tissue integrity. A strong correlation (slope = 23 pmol/mg of tissue weight per percent oral absorption, r2 = 0.9430 by linear regression analysis) of in vitro uptake into everted rings from a 10 mM drug solution versus the known in vivo bioavailability for each compound was observed. These results indicated that under appropriate conditions, in vitro uptake of drug by the everted intestinal ring model closely paralleled known in vivo bioavailability and was relatively independent of pH, cosolvent, and tissue origin.

Interspecies differences in systemic drug availability following subcutaneous pulsatile administration in cattle, sheep, dogs, and rats.

Rats, dogs, sheep, and cattle were implanted subcutaneously with stainless-steel tissue cages. Bolus injections of cefoxitin and ivermectin were administered to the interiors of the tissue cages 11, 32, and 60 days after implantation to simulate pulsatile drug release from an implanted device. Plasma drug levels were determined for 6 h for cefoxitin and up to 8 days for ivermectin. Tissue cages were retrieved 3 and 6 months after implantation for macroscopic and microscopic examination. In dogs and rats, plasma levels of both drugs following administrations to the tissue cages were significantly lower than those following subcutaneous injection, suggesting that the tissue growth around and in the cages posed a barrier to systemic drug availability in those species. In cattle and sheep, the tissue cages and associated tissue did not inhibit systemic availability of either drug as compared with routine subcutaneous administration.

Apoptosis in the cervix of pregnant rats in association with cervical softening.

Cervical ripening in gestation occurs spontaneously in a timely but species-specific fashion as if it were genetically programmed. This study shows that the numbers of dying smooth muscle cells in the cervix increased along with cervical softening in pregnant rats from day 12 of gestation to day 21. The morphological characteristics of the chromatin cleavage in apoptosis are identified. Internucleosomal DNA fragments in the DNA preparations as well as the ladder pattern of double-stranded DNA observed on gel electrophoresis are observed. The deletion and decrease of the cell population in the cervices was demonstrated by a decrease of total DNA in these tissues. The interesting possibility is raised that programmed smooth muscle cell death in the cervix may be involved in the processes of the cervical ripening.

An analysis of the reasons for Japan's low infant mortality rate.

Japan's infant mortality rate in 1991 was four per 1,000, the lowest in the world. Contributing factors are the universal use of the Boshi Kenko Techo (maternal-child health handbook) and universal access to care. Most births occur to women aged 25-29 years and there are few unmarried mothers. Ninety-nine and seven-tenths percent of births are attended by qualified professionals either in hospitals or private clinics, with an average stay of one week postpartum. Abortion is available when contraceptives fail. There are government subsidies for medical, obstetric, and pediatric complications. Japanese citizens are highly literate and seek out medical advice, and their society is organized to support children. Efficient systems of community support, public health education, and excellent medical care encompass events from conception to school age.