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S Monroe

Publications and source records attributed to S Monroe.

At least 37 records · Page 2Linked to original sources
PubMed1990

Taste responses in the parabrachial pons of ovariectomized rats.

Since the early 1970s it has been known that female rats prefer higher concentrations of sweet stimuli compared with males. Recent data have revealed that electrophysiological responses to sweet tastes recorded in the parabrachial nucleus of the pons (PbN), the second relay in the neural pathway for taste, are larger in diestrus female rats compared with those in males. Because it has been shown that ovariectomized rats have lowered preferences for saccharin compared with intact females, it is possible to predict that responses to sweet stimuli in the PbN of ovariectomized rats might be smaller than those in intact females. To investigate this hypothesis, electrophysiological responses to representatives of the 4 basic taste qualities, i.e., salty, sour, sweet and bitter, were recorded in the PbN of ovariectomized rats. Gustatory stimuli included NaCl (0.1 M), HCl (0.01 M), sucrose (0.5 M), quinineHCl (0.01 M) and Na-saccharin (0.004 M). Comparison of taste responses of 49 PbN units in ovariectomized rats with those in the PbN of intact female and male rats showed that responses to sweet stimuli were of comparable magnitude to those in female rats but elevated compared with those in male rats. However, responses of PbN units to quinine appeared to be larger in ovariectomized rats compared with those in the PbN of both intact female and male rats. These results suggest that decreased saccharin preference in ovariectomized rats may reflect a greater sensitivity to the bitter components of the taste of saccharin. Moreover, these data provide evidence that taste responses in the PbN are influenced by both the activational and organizational actions of ovarian hormones.

Animals↗
PubMed1989

Taste responses in the parabrachial pons of male, female and pregnant rats.

Sex-related and pregnancy-related variations in taste preferences have long been known to exist in humans as well as animals. However, the neurophysiological underpinnings of these variations have not yet been described. In an effort to discover whether differences in hormonal state are reflected in the neural processing within the gustatory system, electrophysiological responses to representatives of the 4 basic taste qualities were recorded in the parabrachial nucleus of the pons (PbN) of male, diestrous female and pregnant rats. Results revealed that PbN units in female and pregnant rats showed larger responses to sweet stimuli than units in male rats. Also, a greater proportion of units in female and pregnant rats were classified as sweet-best compared with units in males. This result may correlate with the greater preference for sweet stimuli in female rats compared with males that has been reported in the behavioral literature. Analysis of response profiles with multidimensional scaling techniques showed that units that responded best to a given stimulus were placed near that stimulus for units from males, but not for units from female and pregnant rats. Hierarchical cluster analysis of response profiles suggested 3 clusters of units within each group of PbN units. Response profiles within clusters showed different types of units in male, female and pregnant rats. Collectively, these data suggest that ovarian hormones may act to alter the central processing of gustatory information. Evidence for both activational and organizational effects of ovarian hormones on the gustatory system is discussed.

Action Potentials↗
PubMed1987

Chemoendocrine therapy with prolonged estrogen priming in advanced breast cancer: endocrine pharmacokinetics and toxicity.

Recent efforts to improve response rates in advanced breast cancer have used short, alternating courses of antiestrogen therapy followed by estrogen priming to cytokinetically enhance tumor cell sensitivity to antimetabolites. Based on recent in vitro and in vivo studies, we have introduced a chemoendocrine regimen that uses prolonged courses of estrogen priming. The present protocol consists of alternating monthly cycles of tamoxifen (TAM) and estradiol during which sequential (24-hr) methotrexate, 5-fluorouracil, and leucovorin are administered at 2-week intervals. Twenty-five patients with metastatic breast cancer received greater than 80 endocrine cycles and greater than 300 courses of chemotherapy by this protocol; two-thirds of these patients had previously failed other endocrine or chemotherapy regimens. Most patients experienced grade 1 or 2 myelosuppression or gastrointestinal symptoms during at least one treatment cycle; however, overall toxicity was considered to be mild and therapy was very well tolerated. Serum levels of estradiol, estrone, TAM, and TAM metabolites were measured during all phases of the endocrine cycle in five patients on chronic therapy. Concentrations of TAM and its more abundant metabolite, N-desmethyltamoxifen (N-desTAM), rose twofold during antiestrogen therapy and fell during estrogen priming, with mean levels persisting greater than 100 ng/ml throughout the priming interval. Mean estradiol (E2) and estrone (E1) levels rose during priming and were sustained fivefold and tenfold above the basal postmenopausal levels measured during antiestrogen treatment. Calculating the serum molar ratios of [TAM + N-desTAM]/[E2 + E1] during each phase of the treatment cycle confirmed that estrogen priming was achieved pharmacologically by this endocrine schedule. Clinical remissions were observed in this small patient sample with seven of 18 patients achieving either complete (28%) or partial (11%) responses, and an additional 39% obtaining disease stabilization. Further clinical study is necessary to evaluate the optimal response rate of this regimen and to determine whether cyclic estrogen priming by this schedule results in enhanced tumor cell proliferation in vivo.

Adult↗
PubMed1986

Rate of protamine administration: its effect on heparin reversal and antithrombin recovery after coronary artery surgery.

Patients received a calculated dose of protamine at two different rates (5 min and 30 min) after coronary artery surgery to determine the relationship of the rate of protamine administration with the adequacy of heparin reversal and the rate of return of antithrombin III (AT III) activity. Plasma heparin concentrations and AT III activities were measured at specific times both during and for 3 days after cardiac surgery. Both rates of protamine administration resulted in clinically acceptable clotting, return of the activated coagulation time to normal, and zero heparin concentration after 24 hr. Two hours after protamine administration, patients who received rapidly administered protamine had prolonged coagulation compared to the other group. Normal AT III activity returned the second postoperative day. These results imply that normal postoperative coagulation occurs when protamine is administered over 30 min without a bolus, and that blood is potentially hypercoagulable immediately after heparin reversal because of depressed AT III activity.

Aged↗
PubMed1985

Early gestation: correlation of HCG levels and sonographic identification.

Previous reports have indicated that an intrauterine gestational sac is not usually detected when the maternal serum human chorionic gonadotropin (HCG) is less than 6000 mIU/ml. In order to evaluate this observation, maternal serum HCG concentrations were correlated with sonographic uterine findings in 49 patients with normal early intrauterine pregnancies. Of 37 patients in whom a gestational sac was seen, simultaneous HCG levels were 1800 mIU/ml or more in 36 cases and 357 mlU/ml in one case. In 12 cases in which a gestational sac was not detected, the serum HCG levels were 1400 mIU/ml or less. Thirteen patients had HCG levels of less than 6000 mlU/ml. A linear relation was found between gestational sac size and the exponential rise of HCG levels in early pregnancy (p less than 0.001). Of the 13 patients in whom HCG levels were less than 6000 mIU/ml, the gestational sac measured 10 mm or less in each case. Currently, a gestational sac is always seen when the HCG level is greater than 1800 mIU/ml. Comparison of serum HCG levels with sonographic detection of the gestational sac seems to be a useful method of evaluating early pregnancy.

Amnion↗