A redox-regulated tyrosine phosphorylation cascade in rat spermatozoa

Rat spermatozoa from both the caput and cauda epididymidis were shown to generate superoxide anion (O2-.) both spontaneously and following stimulation with NAD(P)H. Caput spermatozoa gave a significantly greater O2- response to NADPH stimulation than caudal cells, whereas in both cell types the responses to exogenous NADPH and NADH were approximately equivalent. Analysis of H2O2 production revealed that this oxidant was generated only by caudal epididymal cells and only in these cells did the stimulation of reactive oxygen species (ROS) production with NADPH lead to an increase in tyrosine phosphorylation. Stimulation of ROS production with NADPH increased intracellular cyclic adenosine monophosphate (cAMP) levels in both caput and caudal epididymal cells, but only in caudal cells did cAMP stimulate tyrosine phosphorylation, in keeping with the NADPH results. On the basis of these findings we propose that tyrosine phosphorylation in rat spermatozoa is driven by ROS acting via 2 different but complementary mechanisms; O2-. stimulates tyrosine kinase activity indirectly through the elevation of intracellular cAMP while H2O2 acts directly on the kinase/phosphatase system, stimulating the former and inhibiting the latter. Zinc was examined as a potential regulator of this signal transduction cascade and was shown to suppress tyrosine phosphorylation in caput cells but to promote this activity in caudal spermatozoa, possibly through an inhibitory effect on tyrosine phosphatase activity. These results reveal the maturation of a redox-regulated, cAMP-mediated, signal transduction cascade during epididymal transit in the rat that is sensitive to zinc and plays a key role in the control of tyrosine phosphorylation events associated with capacitation.

Robotic enzyme amplification: a comparison of some kinetic properties of bovine liver, Candida utilis and Proteus sp. glutamic dehydrogenases

NADP(H)-specific Bakers yeast glucose 6-phosphate dehydrogenase (BYG6PDH) was paired, in turn, with each of three different source glutamate dehydrogenases (GDHs): NAD(P)-specific bovine liver (BLGDH), NADP-specific Candida utilis (CUGDH) and NADP-specific Proteus sp. (PSGDH) to constitute three enzyme cycling systems; (i) BYG6PDH/BLGDH; (ii) BYG6PDH/CUGDH; and (iii) BYG6PDH/PSGDH. When incorporated into an enzymatic cycling/amplification system for NAD kinase and run on a centrifugal fast analyzer (CFA), the microbial source enzyme CUGDH gave rise to a seven-fold greater amplification rate [21.5 x 10(3) cycles-1 (cph)] relative to that realized (3 x 10(3) cph) using the BYG6PDH/BLGDH cycling pair previously reported. Either of these cycling systems can be used as a flexible and general-purpose module for robotic amplification and data collection of NADP(H) linked enzymes as a user's requirements dictate. Although the BYG6PDH/PSGDH cycling pair produced a respectable cycling rate (14.4 x 10(3) cph), for reasons discussed the PSGDH enzyme was not considered a suitable replacement for BLGDH in an NADP(H) cycling system.

Impact of epididymal maturation on the tyrosine phosphorylation patterns exhibited by rat spermatozoa

As mammalian spermatozoa migrate through the epididymis, they acquire functionality characterized by the potential to express coordinated movement and the competence to undergo capacitation. The mechanisms by which spermatozoa gain the ability to capacitate during epididymal transit are poorly understood. The purpose of this study was to investigate the impact of epididymal maturation on the signal transduction pathways regulating tyrosine phosphorylation, because this process is thought to be central to the attainment of a capacitated state and expression of hyperactivated motility. Western blot and immunocytochemical analyses demonstrated that epididymal maturation in vivo is associated with a progressive loss of phosphotyrosine residues from the sperm head. As cells pass from the caput to the cauda epididymis, tyrosine phosphorylation becomes confined to a narrow band at the posterior margin of the acrosomal vesicle. Epididymal maturation of rat spermatozoa was also associated with an acquired competence to respond to high levels of intracellular cAMP by phosphorylating tyrosine residues on the sperm tail. Immature caput spermatozoa were incapable of exhibiting this response, despite the apparent availability of cAMP and protein kinase A. These findings help to clarify the biochemical changes associated with the functional maturation of spermatozoa during epididymal transit.

Preschool language outcomes of children with history of bronchopulmonary dysplasia and very low birth weight

A prospective follow-up of very low birth weight (VLBW) infants with and without bronchopulmonary dysplasia (BPD) and term control infants was conducted. The effects of BPD and VLBW on speech-language development and specific language impairment at 3 years of age were investigated, controlling for the effects of sociodemographic and other medical risk factors. Groups were compared on cognitive and speech-language outcomes using the Battelle Language and Bayley Mental Scales of Infant Development. Children with a history of BPD had lower receptive language skills than VLBW children without BPD, who in turn had lower receptive skills than term children. Children with a history of BPD also had lower expressive skills than the two comparison groups, whereas VLBW children without BPD did not differ in expressive language from term children. When IQ score was controlled, children with BPD demonstrated specific language impairment in receptive language. The presence of patent ductus arteriosis (PDA) was the best predictor of language deficits and the combined occurrence of PDA and BPD resulted in differentially lower language scores. Neurologic complications, low socioeconomic status, and minority race were also significant predictors of language delay. The findings emphasize the importance of considering both medical and sociodemographic factors in evaluating the risk of VLBW infants for poorer speech-language outcomes.

Arginine supplementation is well tolerated but does not enhance mitogen-induced lymphocyte proliferation in elderly nursing home residents with pressure ulcers

BACKGROUND

Immune function declines with age, increasing risk for infection and delaying wound healing. Arginine enhances immune function and healing of standardized wounds in healthy elderly persons. The purpose of this study was to determine what level of arginine supplementation was orally and metabolically tolerated and effective in enhancing immune function in elderly persons with pressure ulcers.

METHODS

Residents with one or more pressure ulcers were recruited from two local nursing homes. Subjects were randomized to receive 0 g (n = 10; age, 82 +/- 3 years), 8.5 g (n = 11; 81 +/- 3 years), or 17 g (n = 11; 87 +/- 2 years) of supplemental arginine each day for 4 weeks. Oral tolerance, ie, absence of nausea, vomiting, abdominal distention, or diarrhea, was assessed daily. Metabolic tolerance was assessed weekly by evaluating serum electrolytes. Lymphocyte proliferation to phytohemagglutinin and interleukin 2 production were measured at baseline and after 4 weeks of supplementation as indicators of immune function.

RESULTS

Supplemental arginine significantly increased plasma arginine levels and was orally and metabolically tolerated with no complaints of abdominal distress or no clinically relevant changes in electrolyte levels among groups. Lymphocyte proliferation and interleukin 2 production were significantly different between nursing homes. When data from nursing homes were considered individually, arginine supplementation did not enhance the proliferative response. In subjects from nursing home 2 only, there was a 38% and 75% decrease (p < .05) in lymphocyte proliferation with 8.5 and 17 g of supplemental arginine, respectively. Interleukin 2 production was no different among supplementation groups.

CONCLUSIONS

Pharmacologic doses of arginine were well tolerated but did not enhance lymphocyte proliferation or interleukin 2 production in nursing home residents with pressure ulcers. CLINICAL RELEVANCY: Enteral formulas supplemented with pharmacologic levels of arginine are frequently administered to elderly persons. This study demonstrates that the very old can tolerate these nitrogen loads if baseline renal function is normal and fluid intake is encouraged. Further research needs to be completed investigating the effect of arginine supplementation on immune function in this population before recommending arginine use.

Evaluating the predictive value of osteoarthritis diagnoses in an administrative database

OBJECTIVE

To assess the positive and negative predictive values of osteoarthritis (OA) diagnoses contained in an administrative database.

METHODS

We identified all members (> or =18 years of age) of a Massachusetts health maintenance organization with documentation of at least one health care encounter associated with an OA diagnosis during the period 1994-1996. From this population, we randomly selected 350 subjects. In addition, we randomly selected 250 enrollees (proportionally by the age and sex of the 350 subjects) who did not have a health care encounter associated with an OA diagnosis. Trained nurse reviewers abstracted OA-related clinical, laboratory, and radiologic data from the medical records of both study groups (all but 1 chart was available for review). Pairs of physician reviewers evaluated the abstracted information for both groups of subjects and rated the evidence for the presence of OA according to 3 levels: definite, possible, and unlikely.

RESULTS

Among the group of patients with an administrative diagnosis of OA, 215 (62%) were rated as having definite OA, 36 (10%) possible OA, and 98 (28%) unlikely OA, according to information contained in the medical record. The positive predictive value of an OA diagnosis was 62%. In those without an administrative OA diagnosis, 44 (18%) were assigned a rating of definite OA. The negative predictive value of the absence of an administrative OA diagnosis was 78%.

CONCLUSION

Use of administrative data in epidemiologic and health services research on OA may lead to both case misclassification and under ascertainment.

Arginine enhances In vivo immune responses in young, adult and aged mice

Arginine supplementation enhances in vitro lymphocyte proliferation in healthy adult humans and in rodent models. Studies examining the effect of arginine supplementation on in vivo immune responses are lacking. The purpose of this study was to determine whether arginine supplementation could enhance in vivo immune responses in adult mice and reverse known age-associated alterations in immune function of young and aged mice. Mice (1, 10 and 33 mo old) were fed a 2% arginine or an isonitrogenous diet for 2 wk. Delayed-type hypersensitivity to 2,4-dinitrofluorobenzene-challenged ears and changes in popliteal lymph node weights to injected sheep red blood cells were measured. The mean percentage of increase in ear thickness in challenged vs. unchallenged ears was 27, 35 and 24% with arginine supplementation and 7, 12 and 0% with the isonitrogenous diet in the 1-, 10- and 33-mo-old mice, respectively (P </= 0.05 for each age). Across all ages, the mean differences in popliteal lymph node weights were 1.9 +/- 0.3 vs. 1.0 +/- 0.3 mg with the arginine and isonitrogenous diets, respectively (P </= 0. 05). Only the 33-mo-old mice fed the isonitrogenous diet did not respond to this immune challenge. These findings suggest that arginine supplementation may enhance in vivo immune responses and/or reverse age-associated changes.

AANA journal course: update for nurse anesthetists--refrigerated anesthesia-related medications

Medications have strength, expiration date, and storage conditions printed on the medication bottle or package. Some anesthesia medications require refrigeration to maintain the stated strength and safety until the expiration date. These medications may expire in days rather than years when left at room temperature in anesthesia carts or emergency boxes. The following AANA Journal course discusses anesthesia-related medications that require refrigeration and how long potency and safety is maintained out of the refrigerator and provides a chart for future referral.

WAP-TAg transgenic mice and the study of dysregulated cell survival, proliferation, and mutation during breast carcinogenesis

Understanding the process of carcinogenesis is key to developing therapies which might interrupt or reverse tumor onset and progression. Cell growth and death signals are dependent not only upon molecular mechanisms within a cell but also upon external stimuli such as hormones, cell - cell signaling, and extracellular matrix. Mouse models can be used to dissect these complex processes, to identify key signaling pathways operating at different stages of tumorigenesis, and to test the strength of specific interventions. In the WAP-TAg mouse model, carcinogenesis is initiated by expression of the Simian Virus 40 T antigen (TAg). TAg expression is triggered by hormonal stimulation, either during estrus or pregnancy. Breast adenocarcinomas (ranging from well to poorly differentiated) develop in 100% of the female mice by approximately 8 - 9 months of age. Three distinct stages of tumorigenesis are easily identified: an initial proliferation, hyperplasia, and adenocarcinoma. The mean time to first palpable tumor in mice which undergo at least one pregnancy is 6 months. The tumorigenic process is marked by a competition between proliferation and apoptosis and is characterized by cellular acquisition of genetic mutations and increased stromal fibrosis. Protein levels of cell cycle control genes cyclin D1, cdk2, and E2F-1 are increased in these adenocarcinomas. c-Fos protein levels are slightly increased in these cancers, while c-Jun levels do not change. Hormonal exposure alters progression. Estrogen plays a role during the early stages of oncogenesis although the growth of the resulting adenocarcinomas is estrogen-independent. Transient hormonal stimulation by glucocorticoids that temporarily increases the rate of cell proliferation results in tetraploidy, premature appearance of irreversible hyperplasia, and early tumor development. Tumor appearance also can be accelerated through over expression of the cell survival protein, Bcl-2. Bcl-2 over expression not only reduces apoptosis during the initial proliferative process but also decreases the total rate of cell proliferation. This block in cell proliferation is lost selectively as the cells transition to adenocarcinoma. The WAP-TAg model can be utilized to investigate how the basic processes of cell proliferation, apoptosis, DNA mutation, and DNA repair are modified by external and internal signals during mammary oncogenesis.

Hydroxyurea and sodium phenylbutyrate therapy in thalassemia intermedia

Hydroxyurea (HU) and sodium phenylbutyrate (SPB) have been shown to increase fetal hemoglobin (Hb F) levels in patients with thalassemia intermedia. The reported effects of these agents in increasing total Hb, however, have been inconsistent and there have been no studies on the combination of these medications. We describe the clinical response, as determined by increases in total Hb and decreased transfusion needs, in five patients with thalassemia intermedia treated with HU alone or in combination with SPB. All of the patients responded with increased levels of Hb F, but the responses in total Hb varied. Of the five patients, two had a marked response in total Hb in excess of 3 g/dl, two responded modestly with an increase in total Hb of 1-2 g/dl, and one did not respond. Prolonged responses were achieved with low doses of HU (3-10 mg/kg/day) and higher doses were associated with mild reversible hematologic or hepatic toxicity and no further increases in Hb. Sodium phenylbutyrate was added to treatment with HU in two patients, but failed to produce an increase in total Hb despite increasing Hb F levels. Of the four patients who responded to HU with an increase in total Hb, all reported symptomatic improvement and three have not required further transfusions. We conclude that low-dose HU therapy in patients with thalassemia intermedia may increase total Hb levels sufficiently to eliminate the need for transfusions. We, therefore, recommend a trial of HU for thalassemia intermedia patients in whom chronic transfusion therapy is being contemplated.

Donepezil use in managed Medicare: effect on health care costs and utilization

Donepezil is one of the first effective and well-tolerated medications approved for the treatment of Alzheimer's disease (AD). This study examined the impact of donepezil on the costs of AD in a multisite managed care organization between January 1, 1996, and March 31, 1998. A pretreatment/posttreatment study was conducted using retrospective medical and prescription claims data for 70 individuals with AD and related dementias who were prescribed donepezil. The outcomes of interest were costs during the pretreatment and posttreatment phases, which were categorized as medical, prescription, and combined costs. Per diem costs were adjusted for differences in the duration of follow-up. We found that median per diem medical costs were $1.22 lower in the posttreatment phase than in the pretreatment phase (P = 0.02). Moreover, posttreatment costs were reduced in 6 of 7 service settings, with median per diem savings of $0.77 in outpatient care (P = 0.002) and $0.65 in office visits (P < 0.001). In the posttreatment phase, the median per diem costs for prescriptions and all claims combined were higher by $2.59 (P < 0.001) and $2.11 (P = 0.04), respectively. Donepezil treatment was associated with a decrease in medical costs, particularly in the outpatient components of health care. However, overall costs were increased due to the higher costs of medication. Further pharmacoeconomic studies are needed to determine the exact impact of acetylcholinesterase-inhibitor therapy on the overall costs of care for individuals with dementia.

Cost of Alzheimer's disease and related dementia in managed-medicare

BACKGROUND

Managed care organizations (MCOs) will have increased responsibility for the care of large numbers of persons with dementia. There are, however, few studies that inform about decisions of healthcare utilization and expenditures for individuals with dementia in managed care.

OBJECTIVES

To examine in a large MCO whether people diagnosed with dementia have higher healthcare utilization and costs than enrollees without dementia.

DESIGN

A retrospective study of medical and prescription claims.

SETTING

An MCO covering more than 80,000 Medicare enrollees in four geographical locales between January 1, 1996, and March 31, 1998.

SUBJECTS

There were 677 paired cases with and without dementia. Controls were selected randomly and matched to cases on age, gender, and region.

MEASUREMENTS

Summed total costs and number of claims accrued during the study period, as well as a breakdown of costs and claims with respect to place of service, were annualized and adjusted for age, gender, and comorbid conditions. Costs and claims were broken down by place of service.

RESULTS

Dementia prevalence was 0.83%. Mean total costs were 1.5 times higher for patients with dementia relative to controls ($13,487 vs $9,276, P < .001) when annualized and adjusted for level of comorbidity. Almost 75% of the higher costs among cases were linked to inpatient expenses.

CONCLUSIONS

Higher costs for individuals with dementia and disproportionate inpatient costs in this MCO parallel patterns among Medicare enrollees in fee-for-service. The high prevalence of dementia among the oldest old coupled with the high costs of dementia care create very significant clinical and financial incentives for managed care plans to improve the care of members suffering from dementia.

Gain of Bcl-2 is more potent than bax loss in regulating mammary epithelial cell survival in vivo

The impact of gain of Bcl-2 function on mammary epithelial cell survival was compared with loss of Bax function during the two stages of mammary gland involution. Bcl-2 gain of function reduced apoptosis 50% during the first stage and increased cell survival 70% during the second stage. Complete loss of Bax reduced apoptosis by 20% during the first stage without second stage effect. Partial loss of Bax was ineffective but increased cell survival 2.4-fold when combined with Bcl-2 gain. Gain of Bcl-2 function is more potent than loss of Bax function in regulating mammary epithelial cell survival in vivo.

Psychiatric training for family doctors: what do GP registrars want and can a brief course provide this?

CONTEXT

About 40% of British General Practitioners (GPs) train formally in a psychiatric post as part of their general practice training, but such training may not fully meet the needs of future GPs. A specific course in psychiatry for family doctors has run in Manchester for more than a decade.

METHOD

Semi-structured interviews conducted with GP registrars before attending the Manchester course in psychiatry with questionnaire follow-up afterwards to ascertain (a) the training 'wants' of GP registrars and (b) whether the course was providing them.

RESULTS

GP registrars most frequently wanted training in communication skills, how to access the resources that are available to GPs, the detection of psychiatric illness, drug treatment and the management of aggression. The course was successful in satisfying the first three but failed in the last two. There was trend for those who attended Manchester Medical School, which scored significantly higher on number of topics covered at undergraduate level, to perceive a greater need for training than those who attended other medical schools. However, there was no evidence to link self-perception of greater need with having already worked in general practice during postgraduate training.

CONCLUSIONS

More attention needs to be paid to how to address the specific mental health skills training requirements of GP registrars both within the attachment in psychiatry and during the practice year. Preliminary research is required to devise teaching packages before they are entirely satisfactory for GP education.

Thrombogenesis in myocardial infarction and related syndromes: the role of molecular markers in diagnosis and management

Anticoagulant therapy has undergone some major developments in recent years. Conventional drugs that produce anticoagulant effects such as heparin and oral anticoagulants are no longer considered the only candidates for the anticoagulant/antithrombotic management of patients. Recombinant hirudin, glycoproteins IIb/IIIa targeting antibodies, synthetic peptides such as Hirulog and efegatran are being tested for their efficacy. These drugs produce their effects at different sites. To monitor their overall effects on the hemostatic system, molecular markers offer a practical and reliable approach. Markers of thrombin generation are useful for the monitoring of antithrombin drugs whereas, the efficacy of antiplatelet drugs can be assessed by monitoring the platelet release products. Furthermore, polytherapy using several anticoagulant and antithrombotic drugs in combination has been considered. In these situations, the use of molecular markers may also prove to be invaluable. The introduction of simple technology such as the test strip or particle agglutination methods may be available for the measurement of many of these markers in the near future. This will be useful for ready availability and reduced cost for individual marker testing. Furthermore, this type of technology can be used at bedside, off-site, and in doctor's offices. It is clear that the molecular marker profiling provides useful information on the nature of pathophysiology of a given thrombotic disorder. However, for practical use, a cost-effective and simpler assay-based approach will enhance their use, and these tests will be readily accepted at the laboratory and clinical levels.

Readmissions to drug abuse treatment and HIV risk behavior

The objectives of the study were (a) to investigate the characteristics of drug abuse treatment clients who return to treatment and (b) among those with readmissions, to describe changes over time in risk behavior for human immunodeficiency virus (HIV) infection and to identify factors associated with behavior change. Data were derived from a multisite HIV surveillance program in a single community; the program used a unique identifier to link HIV test results and behavioral information from multiple contacts. During a 30-month period, 1994 clients were admitted to three satellite facilities of a single treatment agency: detoxification, long-term residential, and outpatient. Of these clients, 574 (29%) had one or more readmissions to the same or a different facility during the 24 months following the index admission. Drug injectors, those tested for HIV, and those living in the community were more likely to be readmitted to treatment. There was little overall change in HIV risk behavior between the index admission and the readmission furthest in time from the index admission. Clients whose index visit was at the residential facility were more likely to reduce their injection risk behavior than those admitted to the other facilities. Clients readmitted to either the residential or the outpatient facility were more likely to have reduced their injection risk behavior than those readmitted to detoxification. Treatment facility was not associated with sexual risk behavior change. Men were more likely than women to reduce their high-risk sexual behaviors. The results underscore the need for treatment programs to make HIV testing readily available to their clients and to make special efforts to assist female clients to reduce their HIV risk.