Constitutive activation of TCR signaling molecules in IL-2-independent Herpesvirus saimiri-transformed T cells

Both human T cell leukemia virus type I and simian Herpesvirus saimiri (HVS) transform human T cells in vitro. Although IL-2-independent growth in human T cell leukemia virus type I-transformed T cells is associated with constitutive phosphorylation of JAK/STAT kinases, we now demonstrate that different mechanisms may be responsible for the ability of HVS-transformed T cells to proliferate in the absence of exogenous cytokines. The IL-2 independence of an HVS-transformed cell line correlated with constitutive activation of protein tyrosine kinases known to be induced following TCR engagement. Thus, in these cells we observed increased phosphotransferase activity of Lck as well as constitutive tyrosine phosphorylation of the TCR-associated ZAP-70 kinase and expression of the related Syk protein tyrosine kinase. While Syk is generally not expressed in activated T cells, its introduction has been shown to enhance TCR responsiveness. These results suggest that distinct signal transduction cascades can participate in the transition of T cells to IL-2 independence.

Comfort and incidence of abnormal serum sodium, BUN, creatinine and osmolality in dehydration of terminal illness

This prospective clinical study was undertaken to evaluate the effect of spontaneous food/fluid intake on serum sodium and comfort levels in a population of terminal patients (n = 31) receiving clysis or intravenous hydration. The median and mode of serum sodium were within normal limits and 56 percent of the patients were eunatremic. There was no statistically significant difference in comfort scores between predehydration and dehydration phases, and 85 percent had an optimal comfort score. A statistically significant difference was found (p < 0.5) between mean daily comfort scores of those with normal sodium versus those with abnormal sodium; those with hypernatremia were lower but still in the top third comfort levels. Because the sodium was tested using a Chem7, we also were able to calculate the BUN, creatinine, and osmolality. These are presented and compared to other study results. The findings of this study reinforce the belief that fluid depletion in dying patients results in relatively benign symptoms, that serum sodium levels are not always altered with limited intake and that comfort levels can be maintained when the serum sodium is abnormal.

Failure of intravenous ribavirin in the treatment of invasive adenovirus infection following allogeneic bone marrow transplantation: a case report

We report a case of fatal adenovirus infection in a 37-year-old female who underwent allogeneic bone marrow transplantation (BMT) for acute myelogenous leukaemia (AML). Post BMT she developed acute grade II graft-vs.-host disease (aGVHD) requiring high-dose steroids and anti-thymocyte globulin. Additionally, her clinical course was complicated with adenovirus-associated haemorrhagic cystitis and viraemia. Intravenous ribavirin was obtained and administered for 5 days without success; the patient's mental status deteriorated rapidly and she died on day 69 post-transplant. Radiological imaging revealed diffuse cortical necrosis. At autopsy adenovirus was identified in her bladder, kidneys and lungs.

Differential affinity labeling of the two subunits of the homodimeric animal fatty acid synthase allows isolation of heterodimers consisting of subunits that have been independently modified

To explore the domain interactions that are required for catalytic activity of the multifunctional, homodimeric fatty acid synthase (FAS), we have formulated a strategy that allows isolation of modified dimers containing independently mutated subunits. Either a hexahistidine or a FLAG octapeptide tag was incorporated into the FAS at either the amino terminus, within an internal noncatalytic domain, or at the carboxyl terminus. The presence of the tags had no effect on the activity of the wild-type FAS. His-tagged dimers were mixed with FLAG-tagged dimers, and the subunits were randomized to produce a mixture of His-tagged homodimers, FLAG-tagged homodimers, and doubly tagged heterodimers. The doubly tagged heterodimers could be purified to homogeneity by chromatography on an anti-FLAG immunoaffinity column followed by a metal ion chelating column. This procedure for isolation of FAS heterodimers was utilized to determine whether the two centers for fatty acid synthesis in the FAS dimer can function independently of each other. Doubly tagged heterodimers, consisting of one wild-type subunit and one subunit in which the thioesterase activity had been eliminated, either by mutation or by treatment with phenylmethanesulfonyl fluoride, have 50% of the wild-type thioesterase activity and, in the presence of substrates, accumulate a long chain fatty acyl moiety on the modified subunit, thus blocking further substrate turnover at this center. Nevertheless, the ability of the heterodimer to synthesize fatty acids is also 50% of the wild-type FAS, demonstrating that an individual center for fatty acid synthesis has the same activity when paired with either a functional or nonfunctional catalytic center.

The malonyl/acetyltransferase and beta-ketoacyl synthase domains of the animal fatty acid synthase can cooperate with the acyl carrier protein domain of either subunit

The active form of the animal fatty acid synthase (FAS) is a dimer of identical multifunctional polypeptides, each containing seven discrete functional domains, that cooperate to form two centers for palmitate synthesis. To assess the importance of domain cooperation across the subunit interface in the reaction mechanism, we have utilized a strategy based on complementation analysis in vitro of modified FASs carrying critical mutations in specific catalytic domains. Homodimeric FASs carrying the same mutation(s) in both subunits are unable to synthesize fatty acids. As predicted by the current head-to-tail model for the animal FAS, heterodimeric FASs formed between the acyl carrier protein (ACP) mutant and either the beta-ketoacyl synthase (KS) or malonyl/acetyltransferase (MAT) are active in palmitate synthesis, confirming that the KS and MAT domains can cooperate with the ACP domain of the opposite subunit. Contrary to this model however, heterodimeric FASs formed between the KS and MAT mutants, between a MAT, ACP double mutant, and a KS mutant, and between a KS, ACP double mutant, and a MAT mutant are also active in palmitate synthesis, indicating that the MAT and KS domains can also cooperate with the ACP domain of the same subunit. The results of this study reveal an unanticipated element of redundancy in the FAS reaction mechanism in that the amino-terminal KS and MAT domains can make functional contact with the penultimate carboxy-terminal ACP domain of either subunit. A revised model for the FAS is proposed in which the substrate loading and condensation reactions can be catalyzed either by one of the two subunits or by cooperation between domains across the subunit interface.

Abrogation of Smad3 and Smad2 or of Smad4 gene expression positively regulates murine embryonic lung branching morphogenesis in culture

Smad genes are recently identified intracellular effectors for receptor signaling in the BMP/activin/TGF-beta pathway. Since TGF-beta ligands are known to inhibit embryonic lung branching morphogenesis, we tested the hypothesis that Smad genes negatively regulate lung organogenesis. Antisense oligodeoxynucleotides were designed to attenuate Smad3 and Smad2 gene expression in embryonic (E11) mouse lungs over 4 days in culture. Endogenous Smad3 and Smad2 mRNA levels were suppressed by 97 and 91%, respectively, in cultured embryonic lungs when antisense oligodeoxynucleotide (40 microM) to Smad was added, compared to scrambled and sense sequence controls. The corresponding Smad3 and Smad2 protein amounts were also decreased respectively by 86 and 90% in lungs treated with Smad3 and Smad2 antisense oligodeoxynucleotide. Phenotypically, Smad antisense oligodeoxynucleotides resulted in a concentration-dependent increase in lung branching: embryonic lung branching was stimulated by up to 53% in culture with 40 microM antisense oligodeoxynucleotide, whereas both scrambled and sense controls showed no stimulatory effect. Thus, inhibition of endogenous Smad3 and Smad2 gene expression resulted in stimulation of embryonic lung branching similar to that caused by inhibition of TGF-beta type II receptor expression and signaling (J. Zhao et al., 1996, Dev. Biol. 180, 242-257). Abrogation of Smad4 (DPC4), the downstream mediator of Smad3 and Smad2 proteins, with antisense oligodeoxynucleotide, also resulted in increased branching morphogenesis. Furthermore, while TGF-beta alone inhibited lung branching morphogenesis in culture, addition of exogenous TGF-beta 1 could not overcome the stimulatory effect on lung branching of Smad antisense oligodeoxynucleotide treatment. By immunohistochemistry, Smad proteins were localized mainly to the epithelial cells lining the branching distal airways, indicating that Smad genes could regulate lung morphogenesis through mesoderm-endoderm interaction. Our results demonstrate, for the first time, that abrogation of Smad2 and Smad3 or of Smad4 gene expression stimulated early mouse embryonic lung branching morphogenesis in culture, possibly through reversing the negative influence of endogenous TGF-beta signaling upon lung branching morphogenesis.

Postmodernity and a hypertensive patient: rescuing value from nihilism

Much of postmodern philosophy questions the assumptions of Modernity, that period in the history of the Western world since the Enlightment. These assumptions are that truth is discoverable through human reason; that certain knowledge is possible; and furthermore, that such knowledge will provide a basis for the ineluctable progress of Mankind. The Enlightenment project is underwritten by the conviction that knowledge gained through the scientific method is secure. In so far as biomedicine inherits these assumptions it becomes fair game for postmodern deconstruction. Today, perhaps more than ever, plural values compete, and contradictory approaches to health, for instance, garner support and acquire supremacy through consumer choice and media manipulation rather than evidence-based science. Many doctors feel a tension between meeting the needs of the patient face to face, and working towards the broader health needs of the public at large. But if the very foundations of medical science are questioned, by patients, or by doctors themselves, wherein lies the value of their work? This paper examines the issues that the anti-foundationalist thrust of postmodernism raises, in the light of a case of mild hypertension. The strict application of medical protocol, derived from a nomothetic, statistical perspective, seems unlikely to furnish value in the treatment of an individual. The anything goes, consumerist approach, however, fares no better. The author argues that whilst value cannot depend on any rationally predetermined parameters, it can be rescued, and emerges from the process of the meeting with the patient.

Evaluating dental office ergonomic. Risk factors and hazards

Concerns about ergonomic risk factors have been growing among health care and other workers. The authors undertook a study to determine the presence of certain ergonomic risk factors in typical tasks performed by dentists and dental hygienists. They further investigated--by means of electromyography and goniometry--the force, frequency and duration of the task. The study suggests that when a task's duration, force and frequency are accounted for, scaling, polishing, flossing and probing activities do not represent exposure to high ergonomic risk.

Large-scale temporal gene expression mapping of central nervous system development

We used reverse transcription-coupled PCR to produce a high-resolution temporal map of fluctuations in mRNA expression of 112 genes during rat central nervous system development, focusing on the cervical spinal cord. The data provide a temporal gene expression "fingerprint" of spinal cord development based on major families of inter- and intracellular signaling genes. By using distance matrices for the pair-wise comparison of these 112 temporal gene expression patterns as the basis for a cluster analysis, we found five basic "waves" of expression that characterize distinct phases of development. The results suggest functional relationships among the genes fluctuating in parallel. We found that genes belonging to distinct functional classes and gene families clearly map to particular expression profiles. The concepts and data analysis discussed herein may be useful in objectively identifying coherent patterns and sequences of events in the complex genetic signaling network of development. Functional genomics approaches such as this may have applications in the elucidation of complex developmental and degenerative disorders.

How to pass the MRCP (UK) examination--ask a successful candidate!

Recently successful MRCP (UK) candidates were asked to rate the value of clinical experience, reading, practice with past or simulated examination papers and commercially organised courses as preparation for parts 1 and 2 of the examination. With respect to part 1, practice with past and simulated papers was unanimously felt to be of crucial importance with examination-focused reading helpful. Clinical experience was deemed irrelevant and commercially organised courses a matter of individual choice. For part 2, clinical experience was felt to be of fundamental importance but needed to be practised in an 'examination atmosphere'. Both general reading and practice with past and simulated papers were judged helpful and commercially organised courses were perceived to be of more value than for part 1. Trainees should be advised to seek advice on examination preparation from both 'authoritative sources' and their recently successful colleagues.

Production of a Polyhydroxyalkanoate Biopolymer in Insect Cells with a Modified Eucaryotic Fatty Acid Synthase

[This corrects the article on p. 2540 in vol. 62, PMID: 8779593.].

Characterization of the interthiol acyltransferase reaction catalyzed by the beta-ketoacyl synthase domain of the animal fatty acid synthase

The enzyme activity responsible for translocation of saturated acyl chains from the 4'-phosphopantetheine of the acyl carrier protein to the active site cysteine of the beta-ketoacyl synthase in the animal fatty acid synthase has been identified. An enzyme assay was devised that allows uncoupling of the interthiol transfer step from the condensation reaction. Experiments with various fatty acid synthase mutants indicate clearly that catalysis of the transfer of saturated acyl moieties from the 4'-phosphopantetheine thiol to the active site cysteine thiol, Cys-161, is an inherent property of the beta-ketoacyl synthase domain. Catalytic efficiency of the interthiol transferase increases from C2 to C12 and decreases with increasing chain-lengths beyond C12. Malonyl, beta-hydroxybutyryl, and crotonyl thioesters are not substrates for the transferase, whereas the beta-ketobutyryl moiety is a poor substrate. These features of the substrate specificity are exactly as predicted for a transferase that fulfills the proposed role in the fatty acid synthase reaction sequence and indicate that this activity plays an important role in determining the overall specificity of the beta-ketoacyl synthase reaction.

A comparison of duplex scanning and continuous wave Doppler in the assessment of primary and uncomplicated varicose veins

OBJECTIVES

To compare the findings of continuous wave Doppler (CWD) with duplex ultrasound in the assessment of primary and uncomplicated varicose veins, and to determine how their relative roles might be best applied.

MATERIALS AND METHODS

One hundred consecutive limbs were studied in 73 patients with primary (no previous surgery) and uncomplicated (no significant skin change) varicose veins. CWD was employed by a single observer; followed by duplex scanning performed "blind" and independently.

RESULTS

There were 87 limbs with long saphenous incompetence on duplex; all but four of which were correctly identified by CWD, by which technique there were no false positives. (Sensitivity 95%, specificity 100%.) There were 21 limbs with short saphenous incompetence on duplex, all but two of which were recognised on CWD. However, CWD incorrectly diagnosed reflux at the saphenopopliteal junction in five limbs (false positives) with what was, in fact, segmental reflux in the long saphenous trunk on duplex (sensitivity 90%, specificity 93%.) This would have led to inappropriate exploration of the saphenopopliteal junction had surgery proceeded without checking with duplex.

CONCLUSIONS

CWD is adequate for long saphenous incompetence. All "reflux" demonstrated on CWD in the popliteal fossa (about 25% of cases) should be checked by duplex. If this policy had been followed, all the patients in this study would have undergone the correct procedure. The only "errors" would have been missing coexistent short saphenous incompetence in two limbs undergoing appropriate long saphenous exploration.

Use of herbal products, coffee or black tea, and over-the-counter medications as self-treatments among adults with asthma

BACKGROUND

There are few data on the use of alternative therapies in adult asthma and their impact on health outcomes.

OBJECTIVE

The objective of this study was to study the prevalence and morbidity of asthma self-treatment with herbs, coffee or black tea, and over-the-counter (OTC) medications containing ephedrine or epinephrine.

METHODS

We carried out a cross-sectional analysis of interview data for 601 adults with asthma recruited from a random sample of pulmonary and allergy specialists. We estimated the 12-month prevalence of reported use of herbal products, coffee or black tea, or OTC products to self-treat asthma and their association with emergency department visits and hospitalization.

RESULTS

Herbal asthma self-treatment was reported by 46 (8%; 95% confidence interval [CI] 6% to 10%); coffee or black tea self-treatment by 36 (6%; 95% CI 4% to 8%), epinephrine or ephedrine OTC use by 36 (6%; 95% CI 4% to 8%), and any of the three practices by 98 subjects (16%; 95% CI 13% to 19%). Adjusting for demographic and illness covariates, herbal use (odds ratio [OR] 2.5; 95% CI 1.1 to 5.6) and coffee or black tea use (OR 3.1; 95% CI 1.2 to 7.8) were associated with asthma hospitalization; OTC use was not (OR 0.8; 95% CI 0.3 to 2.5).

CONCLUSIONS

Even among adults with access to specialty care for asthma, self-treatment with nonprescription products was common and was associated with increased risk of reported hospitalization. This association does not appear to be accounted for by illness severity or other disease covariates. It may reflect delay in utilization of more efficacious treatments.

Pulmonary and allergy subspecialty care in adults with asthma. Treatment, use of services, and health outcomes

To study the relationship between physician subspecialty practice type and health measures in patients with adult asthma, we prospectively studied 601 adults with asthma. The subjects were recruited from a random sample of board-certified pulmonary or allergy internal medicine subspecialists practicing in northern California; 539 patients (90%) were restudied after 18 months. Structured telephone interviews were used to elicit demographics, clinical variables, and measures of asthma severity, asthma-specific quality of life, and physical function status. At baseline and follow-up, 283 subjects (53%) reported their principal asthma care provider type as a pulmonary specialist throughout and 150 (28%) as an allergy specialist throughout, 53 (10%) switched provider type during follow-up, and 53 (10%) reported that their principal asthma care physician was from neither subspecialist group. Taking into account illness severity and other demographic and clinical covariates, the group whose principal asthma care came from an allergy subspecialist was more likely than the pulmonary specialist-care group to report possessing a peak expiratory flow rate meter (odds ratio [OR], 2.8; 95% confidence interval [CI], 1.8 to 4.6) and less likely to be receiving high-dose inhaled steroids (OR, 0.3; 95% CI, 0.1 to 0.6). Taking into account demographic and clinical covariates, allergists' care was related to worse subject-reported asthma-specific quality of life (P = 0.02), but not to statistically increased risk of hospitalization, decreased physical function, or an increased number of reported health-related restricted-activity days. We observed subject-reported specialist variation in management and health outcomes among adults with asthma not accounted for by differing disease severity or other clinical and demographic variables.

Bridging the gap between inpatient and outpatient providers using organizational elements of assertive community treatment

Even among comprehensive local public mental health systems, there remain large gaps in continuity of care following discharge from inpatient settings. The authors describe a modification of the assertive community treatment (ACT) program model that links inpatients to ongoing community-based care, and provide preliminary evidence of its effectiveness as a component in a rationally organized comprehensive system of care. Given the recent trend toward managed Medicaid arrangements, there will be increased pressure to reduce clients' length of stay in ACT programs. State mental health authorities are cautioned to resist allowing managed care contractors to radically change the conditions under which ACT programs operate until there is greater evidence of the effectiveness of alternative approaches.

Histomorphological and immunohistochemical evaluation of joint changes in a model of osteoarthritis induced by lateral meniscectomy in sheep

OBJECTIVE

To evaluate the histomorphological and immunohistochemical changes induced in cartilages of ovine stifle (knee) joints 6 months after unilateral lateral meniscectomy.

METHODS

Osteochondral sections were obtained from 8 distinct regions of knee joints of 6 adult Merino wethers that 6 months earlier had undergone lateral meniscectomy. Joint regions of 6 age matched sheep housed under identical conditions were used for controls. Serial sections were stained with toluidine blue or immunolocalized with monoclonal antibodies (Mab) 3B3(-), 7D4, and 5B10, which recognize epitopes on proteoglycans.

RESULTS

In control joints the cartilage from the region of the tibial plateau not protected by the meniscus had significantly (p < 0.005) more structural abnormalities than other joint regions. After meniscectomy, only cartilages in the lateral femorotibial compartment showed histomorphological changes consistent with osteoarthritis (OA). The nature and severity of the lesions differed between the topographical regions within the joint. The most severe were found on the lateral femoral condyles and tibial plateaus. Reactivity with Mab 3B3(-), 7D4, and 5B10 was increased only in the lateral compartment cartilages, and was stronger in mild rather than moderate OA.

CONCLUSION

Six month lateral meniscectomy in sheep produces histomorphological and immunohistochemical cartilage changes analogous to those described for early human OA and in other animal models. The severity and type of lesions obtained were dependent on the topographical joint location, but were most evident in cartilages from the lateral compartment.