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Biomedical subjects

P Stein

Publications and source records attributed to P Stein.

At least 55 records · Page 3Linked to original sources
PubMed1995

Effects of hormone replacement therapy on weight, body composition, fat distribution, and food intake in early postmenopausal women: a prospective study.

OBJECTIVE: To evaluate the effects of hormone replacement therapy (HRT) on body weight and composition, fat distribution, and food intake in women entering the climacteric. DESIGN: Prospective clinical study. SETTING: Outpatient menopause clinic at a tertiary medical center. PARTICIPANTS: Sixty-three early postmenopausal women (44 to 54 years old) were prospectively studied for 1 year. They consisted of two groups: group A, 34 subjects who initiated continuous estrogen and progestin treatment (daily oral conjugated estrogen 0.625 mg and medroxyprogesterone acetate 2.5 mg), and group B, 29 women who refused hormonal therapy and served as controls. The age, menopausal status, initial anthropometric measurements (weight, body mass index [BMI], fat mass, and waist-to-hip girth ratio), and daily food intake (total caloric intake and food composition) were similar in both groups. INTERVENTIONS: Anthropometric measurements were performed before commencement of HRT use and after 12 months. MAIN OUTCOME MEASURES: Anthropometric measurements included BMI, waist-to-hip girth ratio, and body composition (the percentage of body fat and water) estimated by means of infrared interactance. Daily food intake was also recorded. RESULTS: The body weight and fat mass increased significantly in both the treatment (73.22 +/- 2.01 [mean +/- SE] to 75.57 +/- 1.12 kg) and the control group (71.45 +/- 3.11 to 73.51 +/- 1.23 kg). However, a significant shift from gynoid to android fat distribution was observed only in the control group (waist-to-hip ratio shifted from 0.80 +/- 0.01 to 0.85 +/- 0.01), whereas no significant change was observed in the treatment group (0.81 +/- 0.01 to 0.82 +/- 0.01). Caloric and macronutrient intake did not change in either group. CONCLUSIONS: These results indicate that continuous daily estrogen and progestin replacement therapy neither prevents nor increases early postmenopausal weight gain and fat accumulation. However, it does minimize the shift from gynoid to android fat distribution.

Adult↗
PubMed1995

Perioperative orientation.

Orientation to the operating room is lengthy, complex, and challenging for everyone involved in its process. To assure success, everyone involved needs to be clear about expectations, goals, and ability to meet the challenges that perioperative patients require. Various teaching methods exist for direct learning activities. They are the most successful when they match the learner's needs and learning style. Critical thinking ability should also be stressed as the orientee learns to apply theory to real life situations.

Inservice Training↗
PubMed1994

Pericentrin, a highly conserved centrosome protein involved in microtubule organization.

Antisera from scleroderma patients that react widely with centrosomes in plants and animals were used to isolate cDNAs encoding a novel centrosomal protein. The nucleotide sequence is consistent with a 7 kb mRNA and contains an open reading frame encoding a protein with a putative large coiled-coil domain flanked by noncoiled ends. Antisera recognize a 220 kd protein and stain centrosomes and acentriolar microtubule-organizing centers, where the protein is localized to the pericentriolar material (hence, the name pericentrin). Anti-pericentrin antibodies disrupt mitotic and meiotic divisions in vivo and block microtubule aster formation in Xenopus extracts, but do not block gamma-tubulin assembly or microtubule nucleation from mature centrosomes. These results suggest that pericentrin is a conserved integral component of the filamentous matrix of the centrosome involved in the initial establishment of organized microtubule arrays.

Amino Acid Sequence↗
PubMed1994

Perioperative considerations of vascular access for dialysis.

Perioperative nurses can be advocates for dialysis patients by being knowledgeable about various access routes, advantages and disadvantages of each, and associated nursing care. The longevity of vascular access devices depends on avoiding infection and blood clot formation. Perioperative nurses need to assess the knowledge level of the dialysis patient before surgical intervention in any situation.

Arteriovenous Shunt, Surgical↗
PubMed1994

Fibroblast behavior in vitro is unaltered by products of staphylococci cultured from silicone implants.

Our previous clinical study supported the concept that capsular contracture is associated with subclinical infection of silicone implants. If bacterial presence, indeed, contributes to capsular contracture, then fibroblast behavior might be expected to change in the presence of bacteria by-products. Therefore, study of possible alteration of fibroblast behavior by bacteria products was undertaken using an in vitro model with cultured dermal fibroblasts. Coagulase-negative staphylococci from silicone mammary and penile implants were isolated and their phenotypic features were characterized. All represented nonbiofilm-producing strains. Products of isolate cultures were noncytotoxic and did not alter matrix reorganization (collagen gel contraction model) or collagen production by fibroblasts. Isolates from either mammary or penile implants exerted similar effects.

Breast↗
PubMed1994

Extended duration of vertical position might impair bone metabolism.

Bone-remodelling is markedly influenced by vectors of gravitational forces. Sleep-deprivation, common during military training, involves a change in the normal balance between horizontal and vertical forces enacting on the skeleton. Stress fractures are likewise prevalent among army recruits. In order to investigate the impact of sleep-deprivation on bone-metabolism, three groups of young, healthy volunteers were selected to exercise the following: 63 h of sleeplessness (17 participants, group A); vertical sleep in a seated position for three consecutive nights (9 participants, group B); controls who slept 6 h a night horizontally (14 participants, group C). During periods of wakefulness, all participants were kept in an upright position. Twenty-four hours' urine collection was strictly observed from two days prior to the experiment until two days after it (1 week). Changes in levels of the most characteristic bone-metabolites, calcium and hydroxyproline indicate an increased bone-resorption in the two experimental groups, but not in controls. The calcium excreted in the fasting urine peaked significantly at 72 h after the beginning of the experiment (+ 170% in group A; + 68% in group B, relative to the basal level). Qualitatively, similar results were obtained with hydroxyproline. On an individual basis, approximately 40% of the participants in either group responded by exceeding urinary-calcium elevation. A comparison of pre-test bone-density between responders and non-responders, reveals a significantly lower bone-density (-5%) in calcium and hydroxyproline excretors. These results suggest a pre-disposition to bone-resorption associated with responsiveness to changes in the balance between gravitational forces.

Adolescent↗
PubMed1994

Aseptic technique: covering all the bases.

An activity was developed which combines standards of practice, JCAHO indicators and a critical aspect of care. Included was development of an inservice on aseptic technique, a unique feature of which was a "practicum." Staff enjoyed the self-directed learning process.

Asepsis↗
PubMed1993

The anorectal angle is not a reliable parameter on defaecating proctography.

Proctography is a standard method of investigating anorectal disorders. The parameters derived from this X-ray include the anorectal angle. The reproducibility of this measurement was assessed in 43 defaecating proctograms viewed by four observers on two separate occasions. Measurements were made at rest and during defaecation straining. Significant intra- and inter-observer variation was found. The anorectal angle is an inaccurate measurement, and should be interpreted with caution.

Anal Canal↗
PubMed1993

Where are we?

Explore the source record for details and available documents.

Humans↗
PubMed1993

Effect of a gonadotropin-releasing hormone agonist on luteinizing hormone receptors and steroidogenesis in ovarian cells.

OBJECTIVE: To examine the effect of a gonadotropin-releasing hormone agonist (GnRH-a), leuprolide acetate (LA), on human chorionic gonadotropin/luteinizing hormone (LH) receptors content and progesterone (P) and estradiol (E2) production in cultured granulosa or luteal cells. DESIGN: Prospective. SETTING: Private Fertility Clinic and National Research Institute. PATIENTS: Twenty patients undergoing in vitro fertilization or gamete intrafallopian transfer programs. RESULTS: Human chorionic gonadotropin/LH receptors in human granulosa cells increased after 48 hours of culture, and LA inhibited such effect. Leuprolide acetate, 1 ng/mL, in the cultures produced an increase in P production. On the contrary, LA inhibited E2 production. Additionally, the in vivo effect of LA (2 micrograms/rat per 7 days) was studied in corpus luteum of superovulated rats. Luteal cells from LA-treated rats in culture produced lower P than the controls but showed an increase in aromatase activity. Luteal LH receptors declined after 48 hours of culture with LA. CONCLUSION: The high doses of gonadotropin necessary to induce ovarian hyperstimulation when GnRH-a is administered could be related with an inhibitory effect of these agonists on LH receptors and aromatase activity.

Animals↗
PubMed1992

Structure-function relationships in the low-affinity mutant haemoglobin Aalborg (Gly74 (E18)beta----Arg).

Haemoglobin Aalborg (Gly74 (E18)beta----Arg) has a reduced oxygen affinity, in both the absence and the presence of organic phosphates; it has a raised affinity for organic phosphates, and it is moderately unstable. By contrast, haemoglobin Shepherds Bush (Gly74 (E18)beta----Asp) has an increased oxygen affinity in both the absence and the presence of organic phosphates, a diminished affinity for organic phosphates and is also unstable. We have determined the crystal structure of deoxyhaemoglobin Aalborg at 2.8 A resolution and compared it to the structures of deoxy- and oxyhaemoglobin A and of deoxyhaemoglobin Shepherds Bush. The guanidinium group of Arg74(E18)beta protrudes from the haem pocket and donates hydrogen bonds to the E and F helices. The carboxylate group of Asp74(E18)beta forms a hydrogen bond only with residue EF6 and is partially buried, which may be why haemoglobin Shepherds Bush appears to be more unstable than haemoglobin Aalborg. To discover why the latter has a low oxygen affinity, we superimposed the B, G and H helices of haemoglobin A, whose conformation is known to be unaffected by ligand binding, on those of haemoglobin Aalborg. This also brought helices E and the haems into superposition, but revealed a shift of the F helix of deoxyhaemoglobin Aalborg towards the EF-corner. This shift is opposite to that which occurs on ligand binding and on transition to the quaternary oxy-structure, and is linked to an increased tilt of the proximal histidine residue away from the haem axis. Since the relative positions of helices E and F and of the haem group are thought to be the main determinants of the changes in oxygen affinity, the shift of helix F may account for the reduced oxygen affinity of haemoglobin Aalborg. The shift may be due to a combination of steric and electrostatic effects introduced by the arginine residue's side-chain. The effects of the arginine and aspartate substitutions at position E18 beta on the 2,3-diphosphoglycerate affinity are equal and opposite. They can be quantitatively accounted for by the electrostatic attraction or repulsion by the oppositely charged side-chains.

Amino Acid Sequence↗
PubMed1992

Subclinical infection of the silicone breast implant surface as a possible cause of capsular contracture.

In order to reexamine the possible association between bacterial presence and capsular contracture, 55 silicone devices (mammary implants or tissue expanders) were cultured at the time of their removal from 40 patients. Special culture techniques were used in an attempt to recover bacteria adhering to the smooth-surfaced implant and encased in glycocalyx biofilm. Bacteria were detected on 56% (15 of 27) of implants surrounded by contracted capsules and on 18% (5 of 28) of those without capsular contracture (p less than 0.05). Only three implants tested positive using routine plating techniques. The predominant isolate was Staphylococcus epidermidis. The concept that capsular contracture is associated with subclinical infection of silicone implants is supported by this study. With changes in the microbiological technique, bacterial recovery and growth occurs at a frequency greater than previously thought.

Adult↗
PubMed1992

Effect of a NADPH generating system on the steroidogenic response in rat luteal cells.

The effect of a NADPH generating system (NADPH-GS) on the function of rat luteal cells was studied. Cells were obtained from pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) primed immature rats and further incubated with a NADPH-GS. This system produced an increase in progesterone production and maximal stimulation was achieved at 1 mM NADP+ (10- to 15-fold). This effect was enhanced by addition of luteinizing hormone (LH 0.25 nM) to the incubation medium. On the contrary, insulin (2 nM) inhibited the effect observed with the NADPH-GS. The conversion of progesterone into 20 alpha-hydroxy-progesterone was not responsible for the changes observed. To analyze the site of NADPH action, pregnenolone and progesterone were measured using two inhibitors of steroid biosynthesis; aminoglutethimide and cyanoketone. The results confirm the specific site of action of NADPH at the mitochondrial conversion of cholesterol to pregnenolone. The effect of NADPH-GS was also observed in cultured purified luteal cells suggesting that the action of NADPH could be mediated by a free entry of the cofactor across the luteal cell plasma membrane. It can be concluded that the addition of NADPH improves the luteal cell incubation conditions and contributes to understanding the regulatory action of LH and insulin on the ovarian steroidogenic process.

Animals↗