Search PubMed⌕ Search

Biomedical subjects

M Morris

Publications and source records attributed to M Morris.

At least 271 records · Page 15Linked to original sources
PubMed1993

Phase resetting of the human circadian pacemaker with use of a single pulse of bright light.

Since the initial studies reporting that light can alter the phase position of the human circadian system, there has been increasing interest in the use of bright light as a tool for manipulating the phase position of the circadian pacemaker. Exposure protocols typically require subjects to receive 2-5 h of exposure over several circadian cycles. As a consequence, bright light treatment can involve a considerable time investment. However, recent studies indicate that a single pulse of bright light can produce significant phase shifts in the circadian pacemaker. If a single pulse of bright light can produce significant phase-shifting effects, multiple-pulse designs may be unnecessary. This study examined the phase-shifting effects of a single 4-h pulse of bright light (12,000 lux) in 14 male and one female subject aged between 19-45 years. With use of a "constant routine" to estimate circadian phase, a single 4-h pulse of light produced significant shifts in the phase of the core temperature rhythm. The timing of the exposure, relative to the core temperature rhythm, determined the degree and direction of the phase shift. Exposure immediately prior to habitual bedtime produced a mean phase delay in the core temperature of 2.39 h (SD = 1.37 h). In contrast, exposure immediately following habitual wake-up produced a mean phase advance of 1.49 h (SD = 2.06 h). In addition, the magnitude of the shift increased the closer the light pulse was to the individual's estimated endogenous core temperature minimum. There was, however, considerable interindividual variability in this relationship.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Hormonal and electrolyte responses to acute isohemic volume expansion in unanesthetized rats.

This study was undertaken to explore the time course of the metabolic response to isohemic blood volume expansion (30%) in normotensive, unanesthetized Sprague-Dawley rats. Whole blood, drawn from a femoral artery catheter of conscious donor rats, was infused into the jugular vein of recipient rats. Blood samples were drawn from a carotid artery of recipient rats at time points beginning immediately post-volume expansion (IPVE) up through 5 days post-volume expansion (PVE). To characterize the attendant compensatory mechanisms, the plasma concentrations of electrolytes and fluid regulatory hormones were determined. Hematocrit began to raise IPVE and was significantly elevated above control IPVE 20, 30, 40, 60, and 90 min, and 2, 4, 6, 8, 12, and 24 hr PVE. Consistent with our current understanding of the hormonal response to excess volume, atrial natriuretic factor was significantly increased above the prevolume expansion (control) values 0-30 min PVE. Surprisingly, plasma aldosterone levels were significantly increased above control at 20 and 30 min and 6 hr PVE, whereas plasma renin activity was significantly decreased 30-40 min PVE. Plasma sodium was not changed from control values except for a significant increase at 6 hr post-volume expansion. Plasma potassium, osmolality, and arginine vasopressin levels were not altered by the volume expansion. These studies delineate the physiologic time scheme operative in the regulation of fluid volume during acute ischemic volume expansion.

Aldosterone↗
PubMed1993

Speaking proficiency after primary tracheoesophageal puncture.

Nineteen patients who had undergone total laryngectomy with primary tracheoesophageal puncture underwent comprehensive testing of speaking proficiency. All patients learned to use tracheoesophageal speech in the immediate postoperative period. Overall, their speech was judged as highly intelligible in both objective and subjective testing when assessed by a panel of naive judges. Eighty per cent of all patients were easily understood on the telephone by a naive listener. During conversational speech, quantitative parameters such as vocal amplitude and fundamental frequency were similar to normal speakers. However they demonstrated limitations in vocal range and in peak amplitude when singing or shouting. The ability to produce high quality tracheoesophageal speech from the immediate postoperative period improves quality of life and expedites the overall rehabilitation after total laryngectomy.

Aged↗
PubMed1993

The sleep-evoked decrease of body temperature.

The circadian rhythm of deep body temperature consists of both an endogenous component and evoked components resulting from exogenous influences. Previous studies of the sleep-evoked effect have failed to control confounding influences, so that the effect of sleep per se has not been established. In the present study, eight good sleepers had their rectal temperatures recorded for 24 hours in each of two laboratory conditions employing a constant routine to control exogenous influences. Sleep was allowed at night in one condition. Following sleep onset, body temperature dropped more rapidly and remained lower than when wakefulness continued over the same time, resulting in a mean sleep-evoked decrease of 0.31 +/- 0.09 degree C. Fourier regression analysis showed a significant 24-hour (circadian) temperature rhythm, together with a 12-hour harmonic rhythm, in each condition. Circadian rhythm parameters were also altered by the sleep-evoked (or masking) effect, with the amplitude increased and the mean decreased when subjects slept at night in the constant routine. It was suggested that a constant routine methodology be used in studies of circadian rhythm differences and that Fourier regression be used in preference to simple cosine curve fitting to give a better approximation of the temperature rhythm.

Adult↗
PubMed1993

Selecting an information system.

Use of new technology can improve productivity without compromising staff nurse time at the bedside. At Borgess Medical Center an interdisciplinary committee co-chaired by nurses analyzed the information system and documentation procedures and developed a plan approved by administration. This resulted in establishment of both a sophisticated point-of-care system and an ongoing patient care informatics committee to further coordinate automation throughout the hospital.

Computers↗
PubMed1992

Excitotoxin paraventricular nucleus lesions: stress and endocrine reactivity and oxytocin mRNA levels.

Electrolytic lesion of the paraventricular nucleus (PVN) of the hypothalamus blocks the tachycardia response to stress. The current study examined the effects of chemical lesion of PVN parvocellular neurons on the cardiovascular and endocrine responses to stress and on the content of hypothalamic oxytocin (OT) mRNA levels. Acute footshock stress increased heart rate in both ibotenic acid lesion and control groups of animals; however, the tachycardia was significantly lower in animals with a PVN lesion than the controls. Lesion of the PVN also attenuated the increase in plasma OT induced by stress, 4-fold in the lesion group versus 20-fold for the controls. There was not a generalized decrease in hormonal responsiveness since the OT response to an osmotic challenge was exaggerated in the lesion group. There was no difference between the groups in the arterial pressure and vasopressin responses to acute stress. Neurotoxin lesions of the PVN also resulted in significant depletions of VP and OT in all levels of the spinal cord and decreased OT levels in the dorsal brainstem. Ibotenic acid lesions of the PVN resulted in no significant changes in OT mRNA in the PVN, SON and PP. In addition, the 48-h dehydration resulted in a significant increase in plasma OT and OT mRNA in the PVN. These data indicate that the parvocellular neurons of the PVN play a role in integration of cardiovascular and endocrine responses to both stressful and osmotic stimuli and provide further evidence that parvocellular OT and VP neurons project to the brainstem and spinal cord.

Animals↗
PubMed1992

Basal and stimulated plasma atrial natriuretic peptide (ANP) concentrations and cardiac ANP contents in old and young rats.

To investigate the ability of the ageing heart to release atrial natriuretic peptide (ANP) we compared the response of awake, trained, chronically catheterized old (20-21 months) and young (4 months) rats to an acute, hypertonic saline challenge. There were no differences between young and old rats in basal plasma concentration of sodium (PNa; old: 141 +/- 3 meq/l; young: 143 +/- 3 meq/l) or ANP (old: 61 +/- 5 pg/ml; young: 67 +/- 12 pg/ml). Five minutes after acute saline challenge, PNa rose in both groups (old: 146 +/- 2 meq/l; young 149 +/- 1 meq/l) and approximately 3-fold increases in plasma ANP levels (182 +/- 24 pg/ml; young: 179 +/- 42 pg/ml). Hearts of old and young rats were assayed for atrial and ventricular ANP content. Atrial ANP levels were similar in old and young rats (13.5 +/- 3.6 vs. 24.9 +/- 8.7 micrograms/g atrial tissue), whereas ventricular ANP content was approximately 4-fold higher in old vs. young rats (153.7 +/- 39.3 vs. 47.5 +/- 6.4 ng/g ventricular tissue). Thus, the ageing rat heart responds equally as well as the young rat to an acute NaCl challenge.

Aging↗
PubMed1992

Minimally invasive vulvar carcinoma: an indication for conservative surgical therapy.

It has been proposed that squamous carcinoma of the vulva with 1 mm or less of stromal invasion can be treated with local resection without inguinal node dissection. A retrospective review of 255 cases of stages I and II vulvar carcinoma demonstrated 24 cases of minimally invasive carcinoma. All cases were subjected to detailed chart review and pathologic confirmation. Mean age at diagnosis was 60 years. Seven patients had a preoperative diagnosis of preinvasive disease, ten had stage I disease, and seven had stage II disease. Fifteen cases had associated vulvar carcinoma in situ. Treatment consisted of local excision in 2 patients, radical wide excision in 11, hemivulvectomy in 5, and radical vulvectomy in 6. Eleven patients had either unilateral or bilateral inguinal node dissection. Five-year life-table survival was 89%. Four patients (17%) developed recurrent dysplasia and four (17%) developed invasive recurrences. One invasive recurrence was in an inguinal node in a patient previously treated with a hemivulvectomy and negative ipsilateral superficial node dissection. Univariate analysis revealed no statistically significant associations between recurrence and age, symptom duration, margin status, location, FIGO stage, or coexisting VIN. Large areas of coexisting dysplasia and variable gross appearance make meaningful application of FIGO staging criteria difficult in lesions with minimal focal invasion. Wide excision or radical wide excision of lesions with "high-risk" VIN or those showing less than or equal to 1 mm of stromal invasion on biopsy is adequate therapy. If final pathologic review demonstrates deeper invasion, a selective lymph node dissection can be performed as a second procedure. Careful surveillance with liberal use of colposcopy and biopsies is indicated in these patients.

Adult↗
PubMed1992

The effect of prolonged cisplatin-based chemotherapy on progression-free survival in patients with optimal epithelial ovarian cancer: "maintenance" therapy reconsidered.

From 1978 until 1988, 116 patients with epithelial ovarian cancer were entered onto one of three consecutive prospective clinical trials involving cisplatin-based combination chemotherapy. They had the following characteristics: (1) stage III or IV disease, (2) grade 2 or 3 tumors, and (3) optimally debulked tumors (residual disease < or = 2 cm). The purpose of the study was to investigate the influence of duration of chemotherapy on survival. The treatment plans were as follows: Trial 1, 12 cycles of cisplatin/melphalan (43 patients); Trial 2, 12 cycles of cisplatin/cyclophosphamide (24 patients); and Trial 3, 6 cycles of cisplatin/cyclophosphamide (49 patients). The total dose of cisplatin was 60 mg/m2 in the first trial and 50 mg/m2 in the second and third trials. Median survival times for the three groups were 58, 29, and 35 months, respectively (NS). Median progression-free survival (PFS) times were 37, 23, and 15 months, respectively (P = 0.0008). Combining patients from the first two trials, the median PFS for patients receiving 12 planned cycles of chemotherapy was 30 months versus 15 months for patients receiving 6 planned cycles (P = 0.0004). Using a forward stepwise Cox proportional hazard model, the use of 12 cycles of therapy and melphalan predicted increased PFS (P = 0.0001 and P = 0.0002, respectively). In view of these results, the lack of published data supporting the superiority of 6 over 12 cycles of chemotherapy, and the rather recent availability of less toxic maintenance therapy (i.e., carboplatin), we believe that a multiinstitutional trial comparing the 6-cycle regimen with more prolonged chemotherapy is justifiable.

Adult↗
PubMed1992

Treatment of small cell carcinoma of the cervix with cisplatin, doxorubicin, and etoposide.

Between July 1986 and February 1991, 10 patients with small cell carcinoma of the cervix were prospectively treated with combination chemotherapy using cisplatin (50 mg/m2) and doxorubicin (50 mg/m2) on Day 1 and etoposide (75 mg/m2) on Days 1-3. All patients underwent an extensive pretreatment metastatic survey and had histologic confirmation of small cell carcinoma prior to entry in the study. Seven patients had stage Ib, 1 stage IIa, and 2 stage IIb. Nine patients received chemotherapy at primary presentation and 1 was treated for recurrent disease. In 6 cases, chemotherapy was given and then followed by radiation therapy. Three patients received chemotherapy following radical hysterectomy and 1 was treated for persistent disease after radiation therapy. Patients received a median of four courses of chemotherapy (range 2-6). Neutropenia was the dose-limiting toxicity with 9 of 10 patients requiring a dose reduction. There was no instance of neutropenic sepsis or other major toxicity. Seven patients had measurable disease at the start of therapy. Three of these patients had a complete clinical response, 1 had a partial response, 2 had stable disease, and 1 had progressive disease (response rate = 57%). The median survival was 28 months. At the time of this report, 4 of 6 patients with stage Ib cancers given primary treatment on this regimen remained free of disease (with 28 months the median follow-up). Our pilot study indicates that this chemotherapy regimen has activity in small cell carcinoma of the cervix and should be further evaluated as an adjuvant to surgery or radiation in patients with early stage disease.

Adult↗
PubMed1992

Uterine papillary serous carcinoma (UPSC) treated with cisplatin, doxorubicin, and cyclophosphamide (PAC).

Uterine papillary serous carcinoma (UPSC) is an aggressive malignancy that accounts for a disproportionate number of intraabdominal failures among endometrial carcinoma patients. The histologic appearance and tendency toward intraabdominal spread resemble those of papillary serous adenocarcinoma of the ovary. Because approximately 70% of untreated ovarian carcinoma patients respond to platinum-based chemotherapy, it has been suggested that UPSC patients might respond to similar treatment regimens. Twenty patients with UPSC were treated with cisplatin, doxorubicin (Adriamycin), cyclophosphamide (PAC) chemotherapy between January 1982 and December 1989. They included 9 patients with advanced primary disease, 5 with recurrence, and 6 who received PAC as adjuvant therapy. Patients received a mean of five cycles of PAC. Only 2 of 11 patients with measurable disease greater than 2 cm achieved complete clinical responses of 12 and 31 months duration; there were no partial responses. Actuarial 5-year survival for all patients was 23%. The mean progression-free interval was 9 months. Patients with clinical stages I or II disease had a higher survival rate than those with stage III or IV disease (P = 0.003). Survival did not correlate with depth of myometrial invasion (P = 0.81) or size of residual tumor following initial surgery (P = 0.16). Estrogen or progesterone receptors were detected in 10 of 11 tumors tested. Seven of 9 patients tested had elevated serum levels of CA-125 (greater than 35 U/ml). Correlation between CA-125 value and clinical course was demonstrated in 3 of 5 patients who had serial measurements. Of all patients, 3 are currently alive; 1 has documented disease. Moderate to severe toxicity was seen in 14 patients (70%). There was one possible treatment-related death from cardiomyopathy. UPSC, despite its histologic and clinical similarities to ovarian carcinoma, was relatively resistant to PAC chemotherapy in this mixed group of patients.

Adult↗
PubMed1992

Superficially invasive squamous cell carcinoma of the cervix.

The microscopic pathologic features of early invasive squamous cell cervical carcinoma are used as determinants for the treatment of these lesions. This study is a retrospective review of 180 patients with squamous cell cervical carcinoma with invasion to a depth of 5 mm or less. Invasion of less than or equal to 1 mm, greater than 1 but less than or equal to 3 mm, greater than 3 but less than or equal to 5 mm was noted in 37, 84, and 59 patients, respectively. The median follow-up was 6.5 years. Four (2.2%) patients developed carcinoma in situ of the vagina and four (2.2%) patients progressed to invasive squamous carcinoma. Pelvic lymph node metastases were rare (1%). No patient has died from recurrent disease. Analysis of numerous clinical and pathological variables identified no risk factors for recurrence. Most (54/68) patients with tumor invading beyond 3 mm or with tumor demonstrating vascular invasion were treated by traditional "radical" methods. This limited a meaningful analysis of the risk of conservative treatment. The reliability of using the existing definitions of microinvasive disease for the guidance of treatment remains controversial. Further clarification may be rendered only with prospective clinical-pathologic studies performed by cooperative groups.

Adult↗
PubMed1992

Bulky endocervical carcinoma: a 23-year experience.

Between 1962 and 1985, 371 patients had initial treatment for bulky endocervical carcinomas of the uterine cervix at The University of Texas M.D. Anderson Cancer Center. All patients had concentric expansion of the cervix by tumors that measured at least 6 cm in greatest transverse diameter. Of the 361 patients treated with curative intent, 211 (57%) had FIGO Stage I disease that was believed to be confined to the uterus, 59 (16%) had FIGO Stage IIA disease, and 101 patients (27%) had FIGO Stage IIB disease. Median follow-up time of surviving patients was 130 months. Actuarial survival rates of 361 patients treated with curative intent were 54% and 48% at 5 and 10 years, respectively. The actuarial pelvic disease control rate was 76% at 10 years. Patients whose tumors were less than 8 cm in maximum diameter (279 patients) had a better survival rate than those with tumors greater than or equal to 8 cm in diameter (92 patients) (p less than 0.01). Of the 282 patients who underwent lymphangiography, survival rate was significantly better for those with negative studies than it was for the 113 patients (40%) with positive or suspicious studies (p less than 0.01). There was no correlation between FIGO stage and survival rate (p = 0.64) or pelvic control rate (p = 0.59). Of patients treated with curative intent, treatment was by radiation alone (RT) in 244 (68%) or by radiation followed by hysterectomy (RT+S) in 117 (32%). Although there has been an overall shift in policy away from the use of adjuvant hysterectomy during the past decade, many patient selection factors also influenced the choice of treatment during the study years, resulting in a significantly higher proportion of patients with adverse prognostic features in the RT group. Patients chosen for treatment with RT alone had a greater likelihood of having tumors greater than or equal to 8 cm (p = 0.03), FIGO stage IIB (p less than 0.01), positive lymphangiogram (p = 0.02), and persistent palpable parametrial disease after external radiotherapy (p less than 0.01). Patients treated with RT alone also had a lower overall survival rate at 10 years than patients treated with RT+S (45% vs 64%, p less than 0.01). Although multivariate analysis suggested that treatment had an independent influence upon survival rate, it was difficult to draw firm conclusions about the value of adjuvant surgery because of the numerous biases in patient selection, some of which may have been difficult to quantify.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗