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C J Connell

Publications and source records attributed to C J Connell.

12 recordsLinked to original sources
PubMed2001

Multivitamin use and colon cancer mortality in the Cancer Prevention Study II cohort (United States).

OBJECTIVE: Multivitamins contain several nutrients, including folic acid, which are hypothesized to reduce colon cancer risk. Previous epidemiologic studies have suggested that effects of multivitamins containing substantial amounts of folic acid (introduced in 1973) may not be evident until 15 or more years since first use. METHODS: We examined the association between daily multivitamin use and colon cancer mortality among 806,397 US men and women in the Cancer Prevention Study II cohort who completed a questionnaire at enrollment in 1982 and were followed for mortality through 1998. RESULTS: After multivariate adjustment, multivitamin use at enrollment showed little association with colon cancer mortality. After 15 years since first use of a multivitamin potentially containing folic acid, we observed slightly decreased risk of colon cancer mortality (rate ratio (RR) = 0.89, 95% confidence interval (CI) 0.80-0.99). Consistent with previous reports, this association was stronger among participants consuming two or more alcoholic drinks per day (RR = 0.71, 95% CI 0.56-0.91). CONCLUSION: Our results are consistent with a modest reduction in colon cancer mortality associated with use of folic acid-containing multivitamins among moderate to heavy alcohol users.

Adult↗
PubMed2001

Vitamin C and vitamin E supplement use and colorectal cancer mortality in a large American Cancer Society cohort.

Some recent epidemiological studies have suggested that use of vitamin C or vitamin E supplements, both of which are important antioxidants, may substantially reduce the risk of colon or colorectal cancer. We examined the association between colorectal cancer mortality and use of individual vitamin C and E supplements in the American Cancer Society's Cancer Prevention Study II cohort. We used proportional hazards modeling to estimate rate ratios among 711,891 men and women in the United States who completed a self-administered questionnaire at study enrollment in 1982, had no history of cancer, and were followed for mortality through 1996. During the 14 years of follow-up, 4404 deaths from colorectal cancer occurred. After adjustment for multiple colorectal cancer risk factors, regular use of vitamin C or E supplements, even long-term use, was not associated with colorectal cancer mortality. The combined-sex rate ratios were 0.89 [95% confidence interval (CI), 0.73-1.09] for 10 or more years of vitamin C use and 1.08 (95% CI, 0.85-1.38) for 10 or more years of vitamin E use. In subgroup analyses, use of vitamin C supplements for 10 or more years was associated with decreased risk of colorectal cancer mortality before age 65 years (rate ratio = 0.48; 95% CI, 0.28-0.81) and decreased risk of rectal cancer mortality at any age (rate ratio = 0.40; 95% CI, 0.20-0.80). Our results do not support a substantial effect of vitamin C or E supplement use on overall colorectal cancer mortality.

Adult↗
PubMed1985

A morphological study of the epididymides of control and estradiol-treated prepubertal dogs.

Treatment of laboratory beagles with 400 micrograms of estradiol benzoate every fourth day from 5 to 20 wk of age severely alters the gross and microscopic morphology of the epididymis. Both stroma and epithelium are affected by estradiol treatment. The peritubular cells of treated animals appear to be fibroblasts separated by broad expanses of collagen, while the control peritubular cells resemble smooth muscle cells separated by small amounts of collagen. The single epithelial cell type present in the treated pup is low columnar and relatively undifferentiated in appearance. These cells appear to be synthetically active based on the accumulation of material within the lumen. The junctions of the epithelial cells of treated animals are occluding, but those of the control are not. The epithelium of control epididymides is composed of columnar principal cells in the caput epididymidis, and principal cells and basal cells in the pseudostratified epithelium of the corpus and cauda epididymidis. The epididymis of the intact, prepubertal dog is responsive to increased estrogen. The presence of estrogen and progesterone receptors (Jones and Connell, 1982) as well as androgen receptors (Younes et al., 1979) suggests that estrogens, progestins, and androgens all may play an essential role in the normal differentiation of the prepubertal epididymis. This is the first description of the ultrastructure of the epididymis of the 20-wk-old dog and the first description of the effect of chronic estrogen treatment on the ultrastructure of the epididymis of the intact prepubertal dog. We propose that the prepubertal dog epididymis is an excellent model system for the study of the hormonal control of epididymal differentiation and development.

Animals↗
PubMed1978

A freeze-fracture and lanthanum tracer study of the complex junction between Sertoli cells of the canine testis.

What appear to be true septate junctions by all techniques currently available for the cytological identification of intercellular junctions are part of a complex junction that interconnects the Sertoli cells of the canine testis. In the seminiferous epithelium, septate junctions are located basal to belts of tight junctions. In thin sections, septate junctions appear as double, parallel, transverse connections or septa spanning an approximately 90-A intercellular space between adjacent Sertoli cells. In en face sections of lanthanum-aldehyde-perfused specimens, the septa themselves exclude lanthanum and appear as electron-lucent lines arranged in a series of double, parallel rows on a background of electron-dense lanthanum. In freeze-fracture replicas this vertebrate septate junction appears as double, parallel rows of individual or fused particles which conform to the distribution of the intercellular septa. Septate junctions can be clearly distinguished from tight junctions as tight junctions prevent the movement of lanthanum tracer toward the lumen, appear as single rows of individual or fused particles in interlacing patterns within freeze-fracture replicas, and are seen as areas of close membrane apposition in thin sections. Both the septate junction and the tight junction are associated with specializations of the Sertoli cell cytoplasm. This is the first demonstration in a vertebrate tissue of a true septate junction.

Animals↗
PubMed1978

Cellular interrelationships in the fetal rabbit testis.

The types and patterns of arrangement of membrane interrelationships in the fetal rabbit testis were studied, using coordinated freeze-fracture, lanthanum tracer and standard transmission electron microscopic techniques. The testicular cords contain a mixture of large spherical germ cells and oval to elongated Sertoli cells. Desmosomes are present between germ cells and Sertoli cells and between adjacent Sertoli cells. Tight junctional specializations of the type found between Sertoli cells in the adult are not seen. In freeze-fracture replicas, short strands of particles of two different size populations are found on the surfaces of Sertoli cells. Similar short strands of particles are present on the membranes of peritubular myoid cells. In lanthanum preparations, the tracer passes freely between peritubular cells and through intercellular spaces within the seminiferous cords, indicating lack of a barrier to its passage throughout the testicular tissue. Prominent macular gap junctions similar to those found between adult Leydig cells are readily observed on the surfaces of fetal Leydig cells. The presence of gap junctions in the fetal testis may be important in coordinating the active testosterone production which occurs during this period of development.

Animals↗
PubMed1977

The effect of HCG on pinocytosis iwthin the canine inter-sertoli cell tight junction. A preliminary report.

The role of tight junctions in permeability barriers is now well established. Other roles for this junction have been postulated but have not been demonstrated. In both adult and prepubertal dogs, stimulation with human chorionic gonadotropin (hCG) results in an increased number of pinocytotic vesicles on the membrane faces enclosed by tight junctions within the inter-Sertoli cell junctions of the testis. It is suggested that these membranous regions, protected from the normal flow of intercellular fluids, may act as regions of selective intercellular exchange.

Animals↗
PubMed1976

A scanning electron microscope study of the interstitial tissue of the canine testis.

Scanning electron microscopy (SEM) is a potent tool that is especially valuable in interpreting the three-dimensional relationships of cells within tissues. This type of information is obtainable from thin sections in transmission electron microscopy (TEM) only by reconstructions of serial sections. The arrangement of the interstitial cells of the testis in relation to the capillaries and lymphatic channels, in particular, is easier to visualize in SEM than in TEM. Cytoplasmic constituents, as well as cell surface modifications, are demonstrable by this technique. The presence of droplets, presumably lipid droplets, both within and on the Leydig cells and the lymphatic endothelial cells, is quite evident. Other cytoplasmic structures are also apparent. For example, the possible functional significance of "openings" that are seen by SEM on the septa that surround lipid droplets is discussed relative to the appearance of the same area as seen in thin sections or in freeze-fracture replicas. SEM should become a very useful method for studying cytological and morphological alterations that occur in testicular tissue that is subjected to physical or chemical manipulation.

Animals↗
PubMed1973

Structure and infectivity of picornaviral RNA encapsidated by cowpea chlorotic mottle virus protein.

Poliovirus and Mengo virus RNA were shown to associate efficiently with cowpea chlorotic mottle virus protein to form pseudovirions. The sedimentation coefficient for the pseudovirions was similar to that of poliovirus, and electron microscope observations showed the Mengo pseudovirions to be similar in size to Mengo virus. Such pseudovirions were infectious and were more resistant to ribonuclease than viral RNA; however, under our assay conditions, their infectivity was about equal to that of viral RNA.

Animals↗