[Is it necessary to operate quickly in patients with significant left main coronary stenosis?]

Although coronary bypass surgery is performed rapidly in the majority of cases of left main coronary stenosis to prevent cardiovascular complications, there is no reported consensus in the literature about the ideal interval between diagnostic coronary angiography and surgery. The aim of this multicenter study was to make an inventory of the serious vascular cardiovascular events which occurred between coronary angiography and surgery to determine possible predictive factors for complications and thereby identify a high risk subgroup requiring immediate revascularisation. The population comprised 283 patients with significant left main coronary disease, out of a total of 8,205 patients who underwent coronary angiography in the university hospitals of Angers, Brest, Nantes, Poitiers and Rennes. A surgical indication was retained in 216 patients. The choice of the operation date depended on clinical data in the presence of an acute coronary syndrome, patients remaining in the intensive care unit and undergoing revascularisation rapidly. Serious cardiac events (death, myocardial infarction, refractory unstable angina and left ventricular failure) occurring while waiting for surgery were rare, observed in only 6.5% of patients. Recent myocardial infarction and, to a lesser degree, unstable angina and/or left ventricular systolic dysfunction, were predictive of serious cardiac complications before surgery. The severity of the left main coronary disease and the association of right coronary disease did not increase the risk of serious cardiac events in the preoperative period. The low incidence of complications demonstrates that this strategy enables patients to wait for surgery with an acceptable risk without having to operate all patients with left main coronary disease as an emergency.

Northern exposure

The operators of Alaska's Alyeska pipeline have often claimed an outstanding record in preventing accidents and environmental damage. This article highlights that, contrary to these claims, Alyeska's operations have brought with them a life-threatening gamble with Alaska's fragile environment. The authors document how the operators of Alyeska have misled the public about the company's real safety record, while at the same time preventing employees from speaking out. As the oil companies consolidate globally, territorial entities such as Alaska can literally assume the character of an oil province.

Community integration and life satisfaction after traumatic brain injury: long-term findings

OBJECTIVE

This study examines the relationship of the degree of community integration to the life satisfaction of persons with traumatic brain injury (TBI).

METHOD

The responses to two self-administered questionnaires measuring aspects of community integration and life satisfaction were studied for 30 persons with TBI who were 26 to 60 years of age.

RESULTS

A significant relationship (rho = .37, p < .05) was found between life satisfaction and social integration (a component of community integration). No significant association was found between the total community integration score and life satisfaction.

CONCLUSION

The results suggest the need for rehabilitation programs to provide long-term assistance with community-based social integration as well as more effective treatment strategies to develop these skills in persons with TBI.

The novel alpha 2-adrenoceptor agonist [3H]mivazerol binds to non-adrenergic binding sites in human striatum membranes that are distinct from imidazoline receptors

The alpha 2 adrenergic agonist [3H]mivazerol labelled two populations of binding sites in membranes from the human striatum. Forty per cent of the sites labelled by 3 nM [3H]mivazerol corresponded to alpha 2 adrenergic receptors as they displayed a high affinity for (-)-adrenaline and for rauwolscine. The remaining binding was displaced by mivazerol with a pIC50 of 6.5 +/- 0.1. These sites displayed higher affinity for dexmedetomidine (pIC50 = 7.1 +/- 0.1), but much lower affinity for clonidine (pIC50 < 5.0) and for idazoxan (pIC50 = 5.1 +/- 0.1). Mivazerol also showed low affinity for the [3H]clonidine-labelled I1 imidazoline receptors and for the [3H]idazoxan-labelled I2 receptors (pIC50 = 5.1 and 3.9, respectively). These results suggest that the non-adrenergic [3H]mivazerol binding sites are distinct from the imidazoline receptors in the human striatum.

The effect of anticipatory discharge orders on length of hospital stay in staff pediatric patients

Effective discharge planning should serve to reduce length of stay (LOS) and lower readmission rates. A combined prospective/retrospective study was undertaken to assess the effectiveness of anticipated discharge order forms in decreasing LOS for staff pediatric patients. Resident physicians provided advance notice of the planned discharge date to nursing staff and patient family members. Patient selection was random, and the data were collected prospectively. These subjects were matched with patients for whom the order form was not used, and the data was collected retrospectively. Matching variables included: diagnosis, age, gender, race, and method of payment. There were 103 matched pairs. LOS was collapsed into low and high categories. There was a significant difference when comparing subject groups (chi 2 = 8.5; P = 0.005). Whereas only 14% of experimental patients were categorized as high LOS, 32% of control patients were classified as such. Physician prediction of discharge date helped decrease patient LOS.

Longitudinal Assessment of Stroke Survivors' Handicap

Proxy agreement for telephone administration of the Craig Handicap Assessment and Reporting Technique (CHART) to community-living individuals 18 months poststroke and their caregivers was assessed and compared to in-person interview of the same sample 1 year earlier. Proxy agreement was adequate for a summary score and for all but one of the dimensions (social integration), replicating prior findings. Physical independence, mobility, and occupation dimensions were intercorrelated. Scores for these dimensions at 6 months poststroke predicted later scores. The study contributes to the validity of the CHART, especially the physical independence, mobility, and occupation dimensions.

Telephone and in-person proxy agreement between stroke patients and caregivers for the functional independence measure

This study examined patient/proxy agreement for telephone administration of the Functional Independence Measure (FIM) to a sample of 25 community-living stroke patients 18 mo post-stroke and their caregivers. Patients had all received in-patient rehabilitation for stroke. Because use of the FIM is increasing for follow-up purposes, it is important to document whether it is appropriate to administer a telephone version to proxy caregivers in situations in which patients cannot answer for themselves. Proxy agreement results were then compared with those obtained for in-person administration of the FIM to the same sample 1 yr earlier. Overall, proxy agreement for telephone administration was excellent for total scores (intraclass correlation was 0.91) and the physical dimension (0.94) and lower for the cognitive dimension (0.52), closely paralleling results obtained for the earlier in-person administration. Reasons for lower agreement on the cognitive dimension are discussed.

[Mutagenesis of the human histamine H1 receptor and design of new antihistamine agents]

The binding cavity of histamine and histamine antagonists is explored using site directed mutagenesis of the human histamine H1 receptor and the amino acids involved in ligand binding are identified. Whereas Asp107 and Phe199 are important for both agonists and antagonists, two additional amino acids (Asn198 and Trp103) are required for efficient histamine binding. The binding site of antagonists is best defined as resulting from a strong ionic bond to Asp107, an orthogonal interaction between one of the aromatic rings with Phe199, and probably a hydrophobic interaction between the second aromatic ring and the lipophilic amino acids of the upper part of TMIV and TMV. This is consistent with structure-activity data of most described antagonists.

The novel antiepileptic drug levetiracetam (ucb L059) appears to act via a specific binding site in CNS membranes

Levetiracetam ((S)-alpha-ethyl-2-oxo-pyrrolidine acetamide, ucb L059) is a novel potential antiepileptic agent presently in clinical development with unknown mechanism of action. The finding that its anticonvulsant activity is highly stereoselective (Gower et al., 1992) led us to investigate the presence of specific binding sites for [3H]levetiracetam in rat central nervous system (CNS). Binding assays, performed on crude membranes, revealed the existence of a reversible, saturable and stereoselective specific binding site. Results obtained in hippocampal membranes suggest that [3H]levetiracetam labels a single class of binding sites (nH = 0.92 +/- 0.06) with modest affinity (Kd = 780 +/- 115 nM) and with a high binding capacity (Bmax = 9.1 +/- 1.2 pmol/mg protein). Similar Kd and Bmax values were obtained in other brain regions (cortex, cerebellum and striatum). ucb L060, the (R) enantiomer of levetiracetam, displayed about 1000 times less affinity for these sites. The binding of [3H]levetiracetam is confined to the synaptic plasma membranes in the central nervous system since no specific binding was observed in a range of peripheral tissues including heart, kidneys, spleen, pancreas, adrenals, lungs and liver. The commonly used antiepileptic drugs carbamazepine, phenytoin, valproate, phenobarbital and clonazepam, as well as the convulsant agent t-butylbicyclophosphorothionate (TBPS), picrotoxin and bicuculline did not displace [3H]levetiracetam binding. However, ethosuximide (pKi = 3.5 +/- 0.1), pentobarbital (pKi = 3.8 +/- 0.1), pentylenetetrazole (pKi = 4.1 +/- 0.1) and bemegride (pKi = 5.0 +/- 0.1) competed with [3H]levetiracetam with pKi values comparable to active drug concentrations observed in vivo. Structurally related compounds, including piracetam and aniracetam, also displaced [3H]levetiracetam binding. (S) Stereoisomer homologues of levetiracetam demonstrated a rank order of affinity for [3H]levetiracetam binding in correlation with their anticonvulsant activity in the audiogenic mouse test (r2 = 0.84, n = 12, P < 0.0001). These results support a possible role of this binding site in the anticonvulsant activity of levetiracetam and substantiate the singular pharmacological profile of this compound. This site remains however to be further characterised.

Sebaceous carcinoma

Sebaceous carcinoma is a rare, aggressive, malignant tumor derived from the adnexal epithelium of sebaceous glands. It may arise in ocular or extraocular sites and exhibits such a variety of histologic growth patterns and diverse clinical presentations that the diagnosis is often delayed for months to years. We discuss incidence as well as clinical, histologic, diagnostic, prognostic, and management issues of this aggressive neoplasm.

The role of dermabrasion and chemical peels in the treatment of patients with xeroderma pigmentosum

We describe our experience with two patients with xeroderma pigmentosum who underwent periodic trichloroacetic acid chemical peels. One also received a full-face dermabrasion. The effect of chemical peeling was more transient than dermabrasion but was associated with less morbidity. Both chemical peeling and dermabrasion provided a prophylactic effect against the development of skin malignancies; the latter had a more pronounced effect.

Pilot histologic and ultrastructural study of the effects of medium-depth chemical facial peels on dermal collagen in patients with actinically damaged skin

BACKGROUND

Chemical peels are employed for a variety of benign and premalignant skin disorders.

OBJECTIVE

We compared clinical and histologic features with ultrastructural changes that occur after medium-depth chemical facial peel.

METHODS

Three men with actinically damaged facial skin underwent a single 35% trichloroacetic acid peel. Biopsy specimens were taken before the peel, and 2 weeks and 3 months after the peel, for histologic examination, electron microscopy, and gel electrophoresis to assess total collagen type I content.

RESULTS

Clinical resolution of actinic damage corresponded with restoration of epidermal polarity. Collagen type I was markedly increased after the peel. Characteristic ultrastructural features of skin after peeling include markedly decreased epidermal intracytoplasmic vacuoles, decreased elastic fibers, and increased activated fibroblasts.

CONCLUSION

Electron microscopic studies after a medium-depth chemical peel of photodamaged skin reveal more profound changes than those seen histologically.

Pharmacological and functional characterisation of the wild-type and site-directed mutants of the human H1 histamine receptor stably expressed in CHO cells

A cDNA clone for the human histamine H1 receptor was isolated from a lung cDNA library and stably expressed in CHO cells. The recombinant receptor protein present in the cell membranes, displayed the functional and binding characteristics of histamine H1 receptors. Mutation of Ser155 to Ala in the fourth transmembrane domain did not significantly change the affinity of the receptor for histamine and H1 antagonists. However, mutation of the fifth transmembrane Asn198 to Ala resulted in a dramatic decrease of the affinity for histamine binding, and for the histamine-induced polyphosphoinositides breakdown, whereas the affinity towards antagonists was not significantly modified. In addition, mutation of another fifth transmembrane amino acid, Thr194 to Ala also diminished, but to a lesser extent, the affinity for histamine. These data led us to propose a molecular model for histamine interaction with the human H1 receptor. In this model, the amide moiety of Asn198 and the hydroxyl group of Thr194 are involved in hydrogen bonding with the nitrogen atoms of the imidazole ring of histamine. Moreover, mutation of Thr194 to Ala demonstrated that this residue is responsible for the discrimination between enantiomers of cetirizine.

Stable expression of human H1-histamine-receptor cDNA in Chinese hamster ovary cells. Pharmacological characterisation of the protein, tissue distribution of messenger RNA and chromosomal localisation of the gene

A cDNA clone for the histamine H1 receptor was isolated from a human lung cDNA library; it encoded a protein of 487 amino acids which showed characteristic features of G-protein-coupled receptors. The percentages of identity of the deduced amino acid sequence with bovine, rat and guinea pig H1 histamine receptors were 82.6%, 79.4% and 73.3%, respectively, whereas these percentages decreased to 74.6%, 66% and 56.7% for the amino acid sequence of the third intracellular loop. The human H1-receptor cDNA was transfected into Chinese hamster ovary cells (CHO) via an eukaryotic expression vector; the receptor protein present on cell membranes specifically bound [3H]mepyramine with a Kd of 3.7 nM. The binding was displaced by H1-histamine-receptor antagonists and histamine. Northern blot analysis indicated the presence of two histamine H1 receptor mRNAs of 3.5 kb and 4.1 kb in various human tissues and an additional mRNA of 4.8 kb restricted to the human brain. Finally, by means of somatic cell hybrids segregating either human or rat chromosomes, the gene for histamine H1 receptor was found to reside on human chromosome 3 and rat chromosome 4.

The paramedian scalp reduction with posterior Z-plasty. A technique to minimize the "slot" defect

BACKGROUND

One consistent and undesired sequela resulting from scalp reductions has been the "slot" or "trough" defect, referring to the scar following the final reduction. Attempts to correct this have not been entirely satisfactory.

OBJECTIVE

To present an approach to minimize the "slot" defect that consists of staged modified paramedian scalp reductions combined with a large posterior Z-plasty during the final reduction.

METHODS

A paramedian crescent-shaped ellipse was marked onto the patient's scalp parallel and adjacent to the existing fringe hair. Subsequent reductions were performed in a similar manner approximately 2 months apart. The final reduction consisted of mobilization and transposition of the large flaps used in the posterior Z-plasty.

RESULTS

Patients who underwent the staged modified paramedian reductions combined with a posterior Z-plasty had significant minimization and adequate camouflage of the undesirable "slot."

CONCLUSION

Combining a large posterior Z-plasty with a paramedian reduction minimizes the slot defect.

Bretylium tosylate binds preferentially to muscarinic receptors labelled with [3H]oxotremorine M (SH or 'high affinity' receptors) in rat heart and brain cortex

Bretylium tosylate is an antiarrhythmic agent. In guinea pig atria it showed the properties of a competitive muscarinic (cholinergic) antagonist and could distinguish between two muscarinic receptor classes or states in cardiac membranes. We decided to further investigate its binding properties at muscarinic cholinergic receptors of the rat heart and brain (cortex), keeping in mind the recently discovered heterogeneity of muscarinic receptor protein. Bretylium tosylate recognized two receptor classes or states in the heart with Ki values of 0.9 and 11 microM. All cardiac membrane receptors showed a homogeneous (11 microM) Ki value for the drug in the presence of GTP in the incubation medium, or after in vivo pretreatment with islet activating protein (IAP). Bretylium tosylate was able (but only at a high concentration, 1 mM) to slow the dissociation kinetics of the tracer, which suggests that it also bound to an allosteric site on the muscarinic receptor, or that it affected the receptor environment. In the brain cortex, as in the heart, bretylium tosylate displayed a high affinity for receptors labelled with the agonist [3H]oxotremorine M (Ki value: 0.8 microM for the SH-or cardiac-type high-affinity receptors), and a 8- to 10-fold lower affinity for cortex M and L receptors. These data suggest that the antagonist bretylium tosylate had binding properties in rat cardiac membranes analogous to those of the partial agonist pilocarpine and that it interacted with a single type of receptor.

Characterization of muscarinic receptors: type M2 (subtype B) on neuro-2A neuroblastoma cells

The binding of the nonselective muscarinic antagonist, [3H]N-methylscopolamine (NMS) to a mouse neuroblastoma cell line (Neuro-2A) and its coupling to the inhibition of adenylate cyclase were characterized. Specific [3H]NMS binding to membrane preparations was rapid, saturable, and of high affinity. Saturation experiments revealed a single class of binding sites for the radioligand. Competition experiments with the muscarinic drugs pirenzepine, AF DX 116, dicyclomine and atropine revealed that the muscarinic receptors present on these cells are predominantly of a single class, subtype B (M2). In addition, agonist binding demonstrated existence of a GTP-sensitive high affinity binding state of the receptors. Coupling of these muscarinic receptors to the adenylate cyclase system was investigated using the muscarinic agonist carbachol which was able to inhibit the prostaglandin (PGE1)-stimulated activation of adenylate cyclase. The agonist carbachol did not stimulate the formation of IP3 above basal levels, which indicated that the receptors are not coupled to phosphatidylinositol metabolism. In conclusion, we show that possessing predominantly one subtype of muscarinic receptor, the Neuro-2A cells provide a useful model for the investigation of the heterogeneity of muscarinic receptors and the relationship of subtype to the coupling of different effectors.

Muscarinic receptor heterogeneity in rat central nervous system. II. Brain receptors labeled by [3H]oxotremorine-M correspond to heterogeneous M2 receptors with very high affinity for agonists

We compared the binding characteristics of muscarinic receptors labeled by [3H]oxotremorine-M ([3H]oxo-M) in homogenates of brain cortex and heart from rat. In both tissues [3H]oxo-M bound, with the same KD (6.5 nM), to a fraction of the receptors labeled by [3H]-N-methylscopolamine ([3H]NMS). This [3H]oxo-M receptor population represented, respectively, 15-20% and 35-40% of the total number of [3H]NMS receptors in cortex and heart. The three unlabeled agonists oxotremorine, carbamylcholine, and pilocarpine, when tested in competition with [3H]oxo-M, displayed a homogeneous super high affinity toward [3H]oxo-M-labeled receptors, and were unable to discriminate between brain and heart receptors labeled by [3H]oxo-M. By contrast, selective muscarinic antagonists showed some selectivity for either brain or heart [3H]oxo-M-labeled receptors. We analyzed competition curves between [3H]oxo-M and secoverine, pirenzepine, AF-DX 116, dicyclomine, or gallamine, assuming the existence of one or two receptor subclasses. Heart muscarinic receptors labeled by [3H]oxo-M were homogeneous M2 receptors of the C type with very low affinity for pirenzepine (Ki = 400 nM). Brain [3H]oxo-M-labeled receptors were heterogeneous receptors, with 30% (the B type) having a higher affinity for dicyclomine and a lower affinity for AF-DX 116 and gallamine than cardiac receptors, whereas the remaining 70% (the C type) showed "cardiac-like" binding properties. Both [3H]oxo-M-labeled subtypes in cortex homogenates had a low affinity for pirenzepine, indicating that [3H]oxo-M labeled only B and C (M2) receptors in this tissue. GTP inhibited completely [3H]oxo-M binding in heart homogenates with an IC50 at 300 nM. In cortex homogenates, GTP showed the same potency, but its efficacy was much lower (with only 30% maximal inhibition). [3H]oxo-M dissociation kinetics were monophasic in heart homogenates and biphasic in cortex homogenates. [3H]oxo-M dissociation from both tissues was slowed by gallamine and d-tubocurarine and accelerated by GTP. We found no correlation between B versus C [3H]oxo-M receptors, GTP-sensitive versus GTP-insensitive receptors, and rapidly versus slowly dissociating receptors, suggesting that [3H] oxo-M labeled a large variety of muscarinic receptor-regulatory protein complexes, all having an SH affinity for agonists.

Muscarinic receptor heterogeneity in rat central nervous system. I. Binding of four selective antagonists to three muscarinic receptor subclasses: a comparison with M2 cardiac muscarinic receptors of the C type

We previously observed that [3H]NMS recognizes three types of muscarinic receptors in rat brain (one M1 subclass with high affinity for pirenzepine, and two M2 subclasses with low affinities for pirenzepine), based on distinct affinity and kinetic constants of [3H]NMS for these three subclasses. In this work, we investigated the binding of four selective antagonists to these three (the M1 and two M2) subclasses. We were able to demonstrate that cardiac-like M2 receptors with low affinity for pirenzepine and low affinity for N-methylscopolamine were present not only in cerebellum (as previously shown; see introduction) but also in cortex, striatum, and hippocampus, and the two M2 receptor subclasses were discriminated by dicyclomine, 4-DAMP, and gallamine, as well as by AF-DX 116 and [3H]NMS. Our findings also suggested that the biphasic association and dissociation kinetics of [3H]NMS observed in various brain regions reflect sequential binding to the different receptors.