The use of harmonic analysis of the strain response in Pb(Mg(1/3)Nb(2/3)) O3-based ceramics to calculate electrostrictive coefficients.

The electromechanical response of ceramics has long been described with Landau Devonshire phenomenology, wherein the strain response is linked to a polynomial expansion in electric field or dielectric displacement. Consequently, the electromechanical response has been modeled with a variety of basis functions. However, these models have failed to accommodate hysteresis and the harmonic response that arises with saturation phenomena. In addition, no quantitative criterion has been used to truncate the expansion. By implementing a discrete Fourier transform in conjunction with Devonshire phenomenology, these three problems can be overcome as demonstrated with a dielectrically aged, lead magnesium niobate relaxor ferroelectric well above its Tmax, i.e., operating in the electrostrictive regime.

The use of colonic irrigation to control fecal incontinence in dogs with colostomies.

OBJECTIVE: To determine if once-daily colonic irrigation results in fecal continence for a 24-hour period in dogs with colostomies and if colonic volume increased in response to the irrigation. STUDY DESIGN: A prospective controlled experimental study. ANIMALS: Four intact male and one intact female mixed breed dogs. MATERIALS: All dogs received left end-on paralumbar colostomies. Four dogs received once-daily colonic irrigation for 8 weeks, whereas the control dog did not. Daily fecal weights were recorded for the length of the study in all dogs. Barium enema studies and volumetric studies were used to determine colonic volumes. RESULTS: Daily fecal weights were significantly decreased in treatment dogs compared with the control dog. Colonic volume increased in irrigated dogs in response to daily irrigation over the 8 week period of the study. CONCLUSIONS: Colonic irrigation resulted in significantly decreased fecal production over a 24-hour period. Therefore management of dogs with colostomies would be more practical and cost effective. It did not result in complete fecal continence in this study. Further clinical studies are indicated to determine if longer periods of irrigation would result in complete continence.

Diagnosis and treatment of pediatric maxillofacial infections.

Infections of the head and neck are very common in children. Determination of the primary etiologic site and organisms responsible for the infection can be difficult, because of the close proximity of the skin, teeth, salivary glands, sinuses, and eustachian tubes. The bacterial flora and site of origin of an infection may vary and should be determined so that the most effective treatment regime can be initiated.

Blood lead levels in children in south central Los Angeles.

We retrospectively reviewed 3 679 pediatric records from King/Drew Medical Center, south central Los Angeles, between 1991 and 1994. Blood lead levels of children were followed to age 18 y. Patients were not referred specifically for lead poisoning. The sample was primarily Latino. Geometric mean blood lead peaked at 6.7 micrograms/dl (0.32 mumol/l) between 2 and 3 y of age. There was a downward secular trend and a seasonal trend. Males had higher lead levels than females. Children who lived in several zipcode areas, in which the lowest family incomes were reported, had higher lead levels. More Latino children had higher lead levels than African American children. Latino children (i.e., 20.2%) who were 1-5 y of age had blood lead levels that were > or = 10 micrograms/dl. Young Latino children in this zone of Los Angeles may be at increased risk for lead exposure.

Validity and reliability of the Constipation Assessment Scale.

Constipation is a significant problem in patients receiving neurotoxic chemotherapeutic agents, narcotic analgesics, antidepressants, tranquilizers, and muscle relaxants. Increasingly, as acute care moves into the community, nurses will need valid and reliable methods of assessing constipation in individuals with cancer. The purpose of this project was to study the validity and reliability of the Constipation Assessment Scale, a new tool designed to assess the presence and severity of constipation. The sample consisted of two groups: a control group of 32 working adults and a patient group of 32 adults at risk for constipation because of treatment with Vinca alkaloids or morphine. Consenting subjects were asked to complete the eight-item Constipation Assessment Scale (CAS). A significant difference in intensity of symptoms between the two groups (t = 6.32, p less than 0.0001) demonstrates the ability of the CAS to differentiate between subjects with and without constipation and thus provides evidence of construct validity of the scale. Further analysis of scores of the two subgroups in the patient group (subjects receiving morphine vs. Vinca alkaloids) revealed a significant difference (t = 2.54, p less than 0.01) in symptom intensity. This latter finding supports the ability of the CAS to differentiate between moderate and severe symptom intensity. Subjects completed the CAS in approximately 2 min. To study the test-retest reliability of the scale, a group of 16 apparently healthy working adults were asked to fill out the CAS twice with a 1-h delay. The two sets of scores were correlated (r = 0.98).(ABSTRACT TRUNCATED AT 250 WORDS)

A simplified technique for nasoendotracheal tube immobilization.

A simplified technique for immobilization of a nasoendotracheal tube is described in which a wide strap of open cell, hypoallergenic, foam-backed fabric is secured to the patient's head with a Velcro fastener.

A comparison of radiographic treatment methods for evaluation of the orbit.

The use of conventional radiography, complex motion tomography, and computed tomography for evaluation of eight patients with orbital floor fractures indicates that CT scans in an axial plane with coronal and sagittal reformations offer the best radiographic evaluation of the orbit.

Postoperative nutritional support in oral and maxillofacial surgery.

The patient sustaining maxillofacial trauma, disease or deformity presents with unique nutritional problems, especially during the postoperative period. By providing a nutritionally adequate diet in the preoperative and immediate postoperative period and during convalescence, complications can be reduced and healing improved. This paper details the nutritional requirements for patients and the indications for, and complications from, total parenteral nutrition and enteral nutritional support.

Bilateral lung abscess associated with a severe masticator space infection.

The clinician should be constantly aware of the danger of aspiration in cases of prolonged sepsis with profuse suppuration. In such cases, it might be wiser to establish dependent extraoral drainage, rather than relying solely on intraoral means. The chances of aspirating septic material and the resultant occurrence of pulmonary abscesses will be lessened.

Pulsatile secretion of gonadotropins and prolactin in male marathon runners. Relation to the endogenous opiate system.

We tested the hypothesis that sustained, strenuous physical training alters the neuroendocrine regulation of pulsatile gonadotropin and/or prolactin secretion in men. Blood was sampled at 20-minute intervals over 8 hours in five endurance-trained men after a 10-15 mile run in the middle of the active training season, and in 11 nonendurance trained normal controls. In these two groups, basal patterns of physiologically pulsatile secretion of LH, FSH, and prolactin (PRL) were not significantly different in relation to the following parameters: mean serum concentration of each of the three hormones (N = 25 samples); areas under the hormone concentration vs. time curves; fractional, incremental, and absolute pulse amplitudes; and pulse frequency, or periodicity. To test for enhanced suppressive effects of endogenous opiates in trained male marathon runners, subjects were administered the potent opiate-receptor antagonist, naltrexone (1 mg/kg). This antagonist significantly stimulated pulsatile LH secretion by increasing mean serum LH values from 10.94 to 13.58 mIU/ml (P = 0.007); area under the LH concentration vs. time curve increased from 5370 to 6510 mIU/ml X 8 hours (P = 0.05) and, pulse frequency rose from 2.8 to 4.9 pulses/8 hours (P = 0.006). Naltrexone also enhanced pulse frequency of FSH secretion from 3.4 to 5.4 pulses/8 hours (P = 0.009), but did not alter serum prolactin concentrations. None of these responses differed significantly from those in normal sedentary controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Do alpha-adrenergic mechanisms regulate spontaneous or opiate-modulated pulsatile luteinizing hormone secretion in man?

Brain noradrenergic mechanisms participate in the excitatory control of episodic LH release in many experimental animals, including the nonhuman primate. In addition, augmentation of pulsatile LH release in the rodent in response to opiate receptor antagonists is dependent upon intact central noradrenergic pathways. The applicability of these tenets to humans is not known. We tested the excitatory influence of brain noradrenergic systems on pulsatile LH secretion in normal men by administering phenoxybenzamine (an irreversible, preferentially postsynaptic, alpha 1-receptor blocker) or alpha-methyldopa (an inhibitor of brain adrenergic transmission). Five normal men underwent repetitive (every 20 min) venous sampling for 8 h to characterize episodic LH release quantitatively under basal conditions and after the administration of naltrexone, a potent opiate receptor antagonist which stimulates puslatile LH release. Subjects received saline, phenoxybenzamine (1 mg/kg, iv, over 90 min), or alpha-methyldopa (250 mg, orally, every 6 h). The following parameters of spontaneous episodic LH secretion were not altered after phenoxybenzamine or alpha-methyldopa administration: mean and integrated serum LH concentrations, LH pulse frequency, LH pulse amplitude (percentage or milliinternational units per ml increment), and absolute peak serum LH values. In addition, the administration of adrenergic inhibitors did not impede the capacity of naltrexone to significantly augment pulsatile LH secretion in these subjects. We conclude that in the doses used, phenoxybenzamine and alpha-methyldopa do not alter spontaneous or opiate-modulated episodic LH release in normal men.