Fast turnaround multiresidue screen for pesticides in produce.

A rapid multiresidue screen for 110 pesticides was applied to 5628 produce samples. Samples were extracted, analyzed, and evaluated within 6 1/2 h of receipt. Analyses were confirmed within a 24 h period on those samples in which a potential residue was found above the U.S. Environmental Protection Agency's tolerance level. A thorough yet quick chromatographic interpretation program is also described.

Sertoli cell function varies along the seminiferous tubule: the proportion and response of transferrin secretors differ between stage-associated tubule segments.

Recent studies from our laboratory demonstrated clearly that only a portion of all Sertoli cells secrete transferrin (TF). These findings raised the possibility that differences in the functional type of Sertoli cells from one location to another may account in part for the stage-related variation in TF release along the seminiferous tubule. In order to address this, Sertoli cells derived from tubule segments corresponding to stages III-V, VII, IX-XI, and XIII of the seminiferous epithelial cycle were subjected to reverse hemolytic plaque assays to determine whether the proportion of TF cells present in those segments were similar or different. We found 21.4 +/- 1.8%, 20.3 +/- 2.0%, 48.3 +/- 2.5%, and 49.2 +/- 3.2% of all cells secreted TF in III-V, VII, IX-XI, and XIII staged segments, respectively. Results obtained from immunocytochemical staining of cells from different sections agreed well with those obtained with plaque assays, indicating that we had detected most, if not all, TF cells in these cultures. In additional experiments, we found that cultured cells from stage III-V and VII responded to FSH or isoproterenol with a large increase in the rate of TF plaque formation, whereas cells from IX-XI and XIII segments appeared to be unaffected. In contrast, bovine fibroblast growth factor caused a marked increase in the rate of TF plaque formation with IX-XI cells and only a slight increase with cells from III-V staged segments. Thus, the manner in which Sertoli cells respond to several modulatory agents appears not only to be stage-dependent, but also to be specific to the agent in question. When taken together, our observations demonstrate that cultured TF secretors obtained from different staged segments of the seminiferous tubule differ in proportion and responsiveness. These findings, when viewed in light of reports of a constant number of Sertoli cells along the seminiferous tubule, suggest that Sertoli cells may acquire and lose the ability to secrete TF or respond to modulation as the seminiferous cycle progresses.

Clinical manifestations of hormonal changes in the menstrual cycle.

The human female reproductive cycle is the result of repeated interactions--giving positive and negative feedback--of pituitary gonadotropic hormones and ovarian sex steroid hormones. If any of the pituitary or ovarian hormones becomes tonically elevated or suppressed, ovulation will cease. The charge to the clinician in evaluating disorders of ovulation is to determine which hormone(s) is tonically elevated or suppressed. Sex steroid hormones exert effects on their target tissues that can be observed directly. These changes aid the clinician in evaluating disorders of ovulation and establishing which hormone(s) is tonically elevated or suppressed. Changes in thermoregulation can be detected by the basal body temperature record. Changes in the vagina can be detected by cytologic examination. Changes in the endometrium can be observed by obtaining a biopsy specimen for histologic examination. Premenstrual molimina suggest to the woman and her clinician that ovulation has occurred. Utilization of these changes in clinical practice aids the clinician in making a specific diagnosis of the cause of anovulation and in developing a treatment plan. Moreover, when the woman is aware of these clinical changes, it makes her a more involved participant in her health care.