Differential nicotinic acetylcholine receptor subunit expression in the human hippocampus

Neuronal nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels composed of alpha and beta subunits with specific structural, functional and pharmacological properties. In this study the distribution of alpha3, alpha4, alpha7, beta2 and beta4 nAChR subunits in the human hippocampus was investigated using immunohistochemistry. Most pyramidal neurons, pre-alpha cells of the entorhinal cortex and dentate granule cells were immunoreactive for all subunits. Small islands of alpha7 immunoreactive cells were present in the outer presubiculum. alpha4 and beta2, and alpha3, alpha4 and beta2 immunoreactive fibre tracts were present in the stratum radiatum and subiculum, respectively, suggesting nAChRs may play a role in modulating inputs to the hippocampus via Schaffer collaterals and along the perforant pathway. Some astrocytes were immunoreactive for alpha3, alpha7 and beta4 subunits. Immunoreactivity to all subunits was noted in association with blood vessels. These results indicate the involvement of multiple nAChR subtypes in the modulation of both neuronal and non-neuronal functions in the human hippocampus.

Multi-scale spatial analysis of human alveolar echinococcosis risk in China

Risk factors for the transmission of Echinococcus multilocularis to humans operate at a range of spatial scales. Over a large area, such as China, regional scale risk is correlated with variation in climatic conditions because of its effect on the spatial distribution of landscapes that can support E. multilocularis transmission in wildlife hosts and the probability of egg survival. At a local scale of a few kilometres, or tens of kilometres, transmission risk is related to the spatial proximity of human populations and landscapes with active transmission. At the patch scale, when considering individual villages or households, human behavioural factors are important and for individuals genetic and immunological factors play a role. Satellite remote sensing can provide landscape information at a range of spatial scales and provide a spatial framework within which to examine transmission patterns. This paper reviews the application of remotely sensed data and spatial data analysis to develop a better understanding of disease transmission and shows how such data have been used to examine human alveolar echinococcosis infection patterns, at a range of spatial scales, in an endemic area in central China.

Human brain nicotinic receptors, their distribution and participation in neuropsychiatric disorders

Mapping of nicotinic acetylcholine receptor (nAChR) subtypes and subunits in human brain is far from complete, however it is clear that multiple subunits are present (including alpha3, alpha4, alpha5, alpha6 and alpha7, beta2, alpha3 and beta4) and that these receptors are not solely distributed on neurones, but also on cerebral vasculature and astrocytes. It is important to elucidate subunit composition of receptors associated with different cell types and pathways within the human CNS in terms of potential nicotinic therapy for a range of both developmental and age-related disorders in which nAChR attenuation occurs. Reductions in nAChRs are reported in Alzheimer's and Parkinson's diseases, dementia with Lewy bodies, schizophrenia and autism, but may not be associated with reduced cortical cholinergic innervation observed in vascular dementia or occur at an early stage in Down's syndrome. Changes in nAChR expression in neuropsychiatric disorders appear to be brain region and subtype specific and have been shown in some instances to be associated with pathology and symptomatology. It is likely that deficits in alpha4-containing receptors predominate in cortical areas in Alzheimer's disease and autism, whereas reduction of alpha7 receptors may be more important in schizophrenia. Changes in astrocytic and vascular nAChR expression in neurodegenerative diseases should also be considered. Studies using both animal models and human autopsy tissue suggest that nAChRs can play a role in neuroprotection against age-related pathology. It is possible that the development of nAChR subtype specific drugs may lead to advances in therapy for both age-related and psychiatric disorders.

Solution of Kramers' problem for a moderately to heavily damped elastic string

We obtain the nucleation rate of critical droplets for an elastic string moving in a double-well potential and subject to noise and damping forces. We obtain this rate for a class of potentials that includes both the asymmetric straight phi(4) and the straight phi(6) potentials. The frequencies of small oscillations about the critical droplet are obtained from a Heun equation. We solve the Fokker-Planck equation for the phase-space probability density by projecting onto the eigenfunction basis. We present a comparison with simulations for the case of the asymmetric straight phi(4) potential.

Laparoscopic Heller myotomy improves esophageal emptying and the symptoms of achalasia

HYPOTHESIS

Laparoscopic Heller esophageal myotomy improves esophageal clearance and symptoms of achalasia in the early and late postoperative periods.

DESIGN

We followed up 98 consecutive patients attending a referral center between February 1, 1994, and July 1, 2000, who underwent laparoscopic myotomy. Operative time, complications, and length of stay were recorded. Postoperative outcomes were assessed using Van Trappen symptom scores (1 indicates no symptoms; 2, symptoms occurring less than once a week; 3, symptoms occurring more than once weekly; and 4, persistent symptoms) and scintigraphic esophageal transit studies.

RESULTS

Of 98 patients, 91 underwent anterior fundoplication. There were no open conversions and 1 mucosal perforation, which was closed laparoscopically without complications. Mean operative times and postoperative days were 3.2 hours and 4.3 days, respectively, in the first 32 patients and 1.7 hours and 2.3 days, respectively, in the last 32 patients (P<.001). Postoperative complications included pneumothorax (4% of patients), atelectasis (5%), and delayed gastric emptying (1%). Seventy-five percent of patients gained weight after surgery. At longest follow-up, 91% of patients were satisfied with the outcome of the procedure. Mean Van Trappen scores for dysphagia improved from 4.0 in the preoperative period to 1.2 at early and late follow-up (P<.001). Fluid retention at 10 minutes in the upright position was 47% in the preoperative period and improved at early and late follow-up to 21% and 20%, respectively (P<.001).

CONCLUSIONS

Laparoscopic Heller myotomy can safely reverse the symptoms of achalasia and improve esophageal transit. These benefits, realized during the early postoperative period, were maintained at longest follow-up.

The hemodynamic effects of inhaled nitric oxide and endogenous nitric oxide synthesis blockade in newborn piglets during infusion of heat-killed group B streptococci

OBJECTIVE

To determine the effects of therapy with inhaled nitric oxide (NO) gas and partial or complete blockade of endogenous NO synthesis with N(omega)nitro-L-arginine (L-NA) on the hemodynamic responses to group B streptococci infusion in newborn piglets.

DESIGN

Randomized, acute intervention study.

SETTING

Animal research laboratory.

SUBJECTS

Twenty-five anesthetized piglets younger than 3 days of age divided into five groups.

INTERVENTIONS

Heat-killed group B streptococci (GBS) were infused systemically until a 50% increase in pulmonary artery pressure (PAP) was obtained, and the infusion was continued for another 2 hrs. The five groups were designed as follows: group 1, sepsis control: continuous GBS infusion, with two brief trials (10 mins) of inhaled NO given after the initial development of pulmonary hypertension and again 2 hrs later; group 2, continuous inhaled NO: NO was given at 40 ppm for 2 hrs during GBS infusion; group 3, high-dose L-NA pretreatment: 10 mg/kg L-NA bolus followed by 1 mg/kg/min before, and continuing throughout, GBS infusion; group 4, high-dose L-NA: same dose as in group 3, but given after the start of the GBS infusion with continuous inhaled NO at 40 ppm; and group 5, low-dose L-NA: 3 mg/kg bolus given after start of GBS infusion with continuous inhaled NO at 40 ppm.

MEASUREMENTS AND MAIN RESULTS

The sepsis controls, group 1, had an increase in PAP, which took 15-45 mins to develop, from a mean of 3.4 (SD 0.7) to 5.9 (1.9) kPa (p < .05), at which time the cardiac index had decreased from 169 (28) to 146 (46) mL/kg/min (p < .05). Brief inhaled NO during the early phase decreased PAP to normal. Two hours later, PAP had increased to 6.1 (0.2) kPa and cardiac index had decreased to 88 (31) mL/kg/min. Inhaled NO after 2 hrs decreased PAP to 3.2 (0.5) kPa and increased cardiac index to 106 (44) ml/kg/min (p < .05). Continuous inhaled NO (group 2) ameliorated the deterioration in cardiac index, which at 2 hrs was 140 (30) mL/kg/min (significantly greater than in the sepsis controls) (p < .05). The L-NA-pretreated animals (group 3) had a greater increase in PAP and pulmonary vascular resistance index when GBS infusion was started. PAP increased from 3.0 (0.7) to 7.3 (1.5) kPa within 15 mins, and cardiac index simultaneously decreased to 68 (20) mL/kg/min. Cardiac index subsequently rapidly deteriorated to 48 (21) mL/kg/min, and only one of five animals survived for 2 hrs. Group 4 animals also developed a rapid deterioration in cardiac output, and only two of five survived for 2 hrs. Group 5 animals had results indistinguishable from group 2 animals.

CONCLUSION

Pulmonary hypertension and shock resulting from GBS infusion in newborn piglets are much worse if endogenous NO production is completely inhibited. Continuous inhaled NO with or without low-dose L-NA inhibits the decrease in cardiac output.

Thoracoscopic versus laparoscopic modified Heller Myotomy for achalasia: efficacy and safety in 87 patients

BACKGROUND

The ideal treatment for achalasia permanently eliminates the dysfunctional lower esophageal sphincter, relieving dysphagia and regurgitation; prevents gastroesophageal reflux; and has an acceptable morbidity rate. Controversy exists concerning whether the thoracoscopic Heller Myotomy (THM) or laparoscopic Heller myotomy (LHM) technique is the best approach to a modified Heller myotomy for achalasia.

STUDY DESIGN

We performed a retrospective comparison of the patient characteristics, operative results, postoperative symptoms, and the learning curves for the procedures of 24 patients undergoing THM and 63 patients undergoing LHM between 1991 and 1998.

RESULTS

Preoperative patient variables in each group revealed similar distributions for age, gender, and prevalence of previous pneumatic dilation. Mean operating room (OR) times were 4.3 hours (range 2.9 to 5.6 hours) for THM and 3.0 hours (range 1.5 to 6.5 hours) for LHM (p = 0.01). Three esophageal perforations occurred in the THM group and two in the LHM group. Conversion to an open procedure took place in five THM operations (21%) and one LHM operation (2%) (p = 0.005). There were no postoperative esophageal leaks. Mean postoperative length of stay (LOS) for THM was 6.1 days (range 1 to 17 days) and for LHM was 4.0 days (range 1 to 12 days) (p = 0.03). Learning-curve analysis of the first 24 LHM patients compared with the most recent 24 revealed greater OR time in the first 24 mean 3.6 hours, (range 2.0 to 6.5 hours) versus mean 2.3 hours, (range 1.5 to 3.7 hours; p = 0.01), and greater LOS mean 5.5 days, (range 3 to 12 days) versus mean 3.1 days, (range 1 to 8 days; p < 0.01). One esophageal perforation occurred in each subgroup. A similar analysis in the first 12 THM patients compared with the most recent 12 revealed no significant improvement in OR times or LOS. Three esophageal perforations occurred in the latter subgroup only. All patients had preoperative daily dysphagia to solids. Followup data for LHM (n = 49) (median 17 months, range 1 to 39 months) and THM (n = 15) (median 42 months, range 1 to 69 months) revealed no or minimal dysphagia in 90% (44 of 49) after LHM and 31% (4 of 13) after THM (p < 0.01). No or minimal heartburn was present in 89% (41 of 46) after LHM and 67% (8 of 12) after THM (p < 0.05). Regurgitation was absent or minimal in 94% (46 of 49) after LHM and 86% (12 of 14) after THM (p = 0.3).

CONCLUSIONS

LHM was associated with decreased OR time, decreased rate of conversion to an open procedure, and shorter LOS compared with THM. LHM was superior to THM in relieving dysphagia and preventing heartburn. LHM may be the preferred surgical treatment of achalasia in some patients.

Surgical management of adenocarcinoma of the cardia

BACKGROUND

The incidence of adenocarcinoma of the cardia is increasing. The surgical management remains controversial. The present study reviews our experience with surgically resected adenocarcinoma of the cardia.

METHODS

A retrospective review of 153 cases of surgically resected adenocarcinoma of the cardia was performed. Preoperative radiotherapy was used in 31 patients. The surgical approach, morbidity, mortality, impact of preoperative radiotherapy, and survival were determined.

RESULTS

The type of resection performed was a transhiatal esophagogastrectomy in 78%, a transthoracic esophagogastrectomy in 21%, and a transabdominal esophagogastrectomy in 1%. The in-hospital mortality rate was 4%. The frequency of complications was not associated with the use of preoperative radiotherapy or surgical approach. The 1-year (61%), 2-year (38%), 3-year (23%), and 5-year (16%) survival were not affected by the use of preoperative radiotherapy or surgical approach. Survival was significantly associated with stage and the presence of lymph node metastasis.

CONCLUSIONS

Adenocarcinoma of the cardia is associated with a poor long-term prognosis. The long-term survival does not appear to be affected by the use of preoperative radiotherapy or by surgical approach.

A Quantitative Study of Soil-Plant Relations in the Eastern Goldfields of Western Australia

The soil and plants at a 27.4 ha field site near Kalgoorlie, Western Australia, were surveyed and analysed with multivariate statistics. Cluster analysis identified four distinct plant communities at the study site. These were: Acacia acuminata shrubland Eucalyptus gvfithsii woodland Eucalyptus salrnonophloia woodland 'Ground Covers' - areas characterised by the presence of generalist herbs, low shrubs and weeds, and the absence of dominant upper storey species. Discriminant function analysis identified site elevation and soil exchangeable Ca as the primary environmental discriminants between the plant communities. Using these two variables, sample points were classified into one of the four plant communities. The two methods of classification matched well, with classification based on the two environmental variables providing an indication of which plant community would be most likely to establish in disturbed areas. This type of information can be important to revegetation programs in the region, guiding the use of appropriate plant species under different rehabilitation conditions. Key wcrds: environmental variables, plant communities, multivariate analysis, classification, revegetation

Laparoscopic esophageal myotomy and anterior partial fundoplication for the treatment of achalasia

BACKGROUND

The purpose of this study was to determine the initial results of laparoscopic esophageal myotomy and anterior fundoplication in the treatment of 26 patients with achalasia.

METHODS

Operative time, complications, and length of hospitalization were recorded for each patient. Postoperative outcomes were assessed by a standardized patient questionnaire, 24-hour esophageal pH studies, and esophageal transit studies.

RESULTS

Twenty-six consecutive patients with class IV dysphagia underwent a laparoscopic esophageal myotomy and anterior partial fundoplication, with a single incidence of intraoperative esophageal perforation. The mean operative time was 3.5 hours. The median length of hospitalization was 5 days. Of the 21 patients for whom follow-up was available (median follow-up, 4 months), 19 (90%) were satisfied and 2 (10%) were somewhat satisfied with their surgery. After operation, 14 of the 21 patients (67%) reported no dysphagia (class I), whereas 6 (28%) had class II dysphagia (less than once per week) and only 1 (5%) had class III dysphagia (greater than once per week). Liquid-phase esophageal transit studies (n = 14) revealed a significant improvement in esophageal clearance in the supine position from 18% before operation to 44% after operation (p = 0.006). Distal esophageal acid exposure was normal in 6 of 7 patients.

CONCLUSIONS

These early results suggest that laparoscopic esophageal myotomy and anterior partial fundoplication provides efficacious treatment of achalasia.

British motor neuron disease twin study

OBJECTIVES

To investigate the cause of sporadic motor neuron disease (MND) by twin study, so allowing (1) estimation of the genetic contribution, and (2) collection of matched pairs for a case-control study of possible environmental factors.

METHODS

10872 death certificates bearing the diagnosis MND were collected from 1979 to 1989 inclusive. Inspection of individual birth entries allowed identification of potential twins. The status of each co-twin was determined and contact made through the National Health Service Central Register (NHS-CR) and their general practitioner (GP). The diagnosis of MND was verified via the co-twin and relatives, and medical records where available. Zygosity was assessed using a recognised questionnaire. Details concerning environmental exposures and health were gathered by interview of cotwin and relatives using a semistructured questionnaire. Heritability (h2) of MND was estimated, and the environmental information was analysed by conditional logistic regression modelling.

RESULTS

Seventy seven probands were identified, of whom 26 were monozygotic and 51 dizygotic. Four monozygotic probands were concordant, but two probands came from a family known to have familial MND. The estimated heritability was between 0.38 and 0.85. Most environmental risk factors were not significant. Regular vehicle maintenance (odds ratio (OR) = 7.0; 95% confidence interval (95% CI) 1.3-89.9) and occupational paint usage (OR = 3.75; 95% CI 1.0-17.1), however, occurred significantly more often in the affected cases.

CONCLUSIONS

This "death discordant" method for twin collection has proved to be viable, and has allowed the ascertainment of a large population sample in a rare disease. The genetic role in sporadic MND is substantial, and higher than expected. Exposure to industrial chemicals, particularly constituents of petrochemicals and paints, may contribute to the aetiology of MND.

Comparison of total versus partial laparoscopic fundoplication in the management of gastroesophageal reflux disease

BACKGROUND AND METHODS

A comparison of total vs. partial laparoscopic fundoplication was conducted in 89 patients from July 92 to June 96. Parameters examined were operating room (OR) times, conversion rates, and perioperative complications. Patient satisfaction, control of symptoms, and late complications were assessed by follow-up at a mean of 6 and 15.4 months.

RESULTS

There were six conversions to open surgery resulting in 48 laparoscopic total (LTF) and 35 laparoscopic partial (25 anterior and 10 Toupet) fundoplications (LPF). The following results were obtained for each respectively: preop Demeester score 44 vs. 39; OR time 2.9 vs. 2.5 hours; length of stay 3.6 vs. 4.1 days; early morbidity 25% vs. 1%. There were no mortalities. At a mean follow-up of 6 months, new-onset dysphagia was present in 8 (17%) vs. 2 (8%), respectively (NS), and both total and partial fundoplications appeared successful in controlling symptoms (98% vs. 97%). At a mean follow-up of 15.4 months, heartburn was resolved or improved in 76% vs. 87% (NS); regurgitation was improved or resolved in 93% vs. 93%; and patient satisfaction with the procedure was present in 93% vs. 97% (NS). Persistent dysphagia was present in 7.3% vs. 10.3% (NS) of patients. Early satiety was present more often in the partial fundoplication group (56% vs. 83% P = .03).

CONCLUSIONS

Early follow-up suggests equal efficacy in controlling symptoms and in achieving patient satisfaction. A 6-month follow-up suggested a higher incidence of new dysphagia in the total fundoplication group; however, at 15-month follow-up there was no significant difference.

Catheterisation technique: overcoming gel blockage

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Twin study using mortality data: a new sampling method

BACKGROUND

To evaluate the success of a novel approach to twin studies using death discordant twin pairs in a disease of low prevalence.

METHOD

A population study based on all registered deaths at the Office of Population Censuses and Surveys of England and Wales, classified under the ICD code 335.2 (motor neuron disease [MND]) for the period 1979-1989 inclusive. From the above database of 10,872 people, individuals born after 31 December 1899 were traced in the Birth Indices for England & Wales to enable identification of possible twins. In all 131 twin pairs were found and the co-twin details were sent to the National Health Service Central Register (NHS-CR) to enable location of the relevant Family Health Services Authority and thence the co-twin's general practitioner (GP). A letter requesting access was sent to the family practitioners. If given, the co-twin can be approached and interviewed.

RESULTS

The search produced: 54 living co-twins; 31 who died as adults; 29 infant deaths; 5 emigrated; 3 incorrectly diagnosed index twins; and 9 untraceable co-twins. Among the adult deaths two concordant pairs were identified. This has created the largest twin population sample worldwide for MND.

CONCLUSION

This new twin study method is clearly viable, and has produced a large unbiased sample compared to that possible using traditional methods. It relies heavily on the accuracy of death certificates and zygosity reporting by living co-twins, but is possibly the only way of collecting twins in rare conditions.

Inhaled nitric oxide improves oxygenation in piglets with meconium aspiration

We hypothesized that nitric oxide (NO) inhalation in a model of meconium aspiration in newborn piglets would decrease pulmonary vascular resistance. Seven neonatal piglets were obtained at less than 48 hr of age and instrumented under fentanyl anesthesia. Inhaled NO (40 parts per million) was administered during normoxia and again after hypoxia was induced by reducing FiO2 to 0.13. During normoxia NO inhalation caused a fall in pulmonary artery pressure from a mean of 3.15 (SD 0.8) kPa to 2.84 (SD 0.7) kPa (P < 0.01). Hypoxia (mean arterial O2 saturation 35%) increased PA pressures to a mean of 5.4 (SD 1.6) kPa and NO administration during hypoxia decreased PA pressures to 3.6 (SD 1.2) kPa (P < 0.001). In order to determine the effects of NO in a model of meconium aspiration, 6 to 7 mL/kg of 20% human meconium in normal saline was instilled into the trachea. This procedure induced hypoxemia (mean SaO2 43.4%, SD 19), respiratory acidosis, (mean PaCO2 12.1 kPa, SD 0.5; mean pH 7.04, SD 0.03), and pulmonary arterial hypertension (mean pulmonary artery pressure 6.0 kPa, SD 1.3) despite ventilation with 90% oxygen. Inhaled NO was then administered in concentrations of 5, 10, 20, 30, 40, 60, and 80 parts per million in random order according to a Latin square design.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of intraabdominal CO2 insufflation in the piglet

Adult intraabdominal surgery performed with the minimal-access technique has created a revolution in surgery. This technique has remained largely unused for pediatric surgical procedures because of concerns regarding its safety and efficacy. Presently, intraabdominal insufflation of CO2 is the preliminary step to performing minimal access surgery. In this study, an animal model was developed to determine the effects of intraabdominal CO2 insufflation in the infant. Eight piglets (4 to 6 kg; 14 to 19 days of age) were instrumented under fentanyl anesthesia to allow measurement of arterial blood pressure (BP), central venous pressure (CVP), heart rate (HR), cardiac index (CI), inferior vena cava pressure (IVCp), inferior vena cava flow (IVCf), mediastinal pressure (Mp), partial pressure of CO2 (PaCO2), and minute ventilation (VE) at baseline and during 1 hour of CO2 insufflation to a pressure of 15 mm Hg and again when ventilation was increased to control PaCO2 levels. Continuous recording of data allowed time-course analysis of 15-minute blocks to determine the rate of change of measured variables. A second group of 6 piglets (4 to 6 kg) underwent the same instrumentation, but their baseline values were compared with those during N2O insufflation to isolate the effects of increased intraabdominal pressure. During CO2 insufflation alone, PaCO2 increased by 31% (P < .0001). This increase occurred within the first 15 minutes of insufflation and then remained stable. The increase was likely the result of increased CO2 absorption from the peritoneal cavity because VE was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Stereoselective Synthesis of (±)-(cis-6-Methyltetrahydropyran-2-yl)acetic Acid

The title compound (1) has been synthesized in seven steps and in 42% overall yield from the nucleophilic diene (2). The relative configuration of (1) has been confirmed by a single-crystal X-ray study.

Nitric oxide reverses acute hypoxic pulmonary hypertension in the newborn piglet

Inhaled nitric oxide has been reported to act as a specific pulmonary vasodilator. We used the newborn piglet to create acute hypoxic pulmonary hypertension and examined the effect of inhaled nitric oxide in this model. Six newborn piglets were instrumented in order to measure cardiac index, pulmonary arterial pressure, and systemic arterial pressure. Pulmonary hypertension was induced by reducing the fraction of inspired oxygen to 0.12 to 0.14. With hypoxia (arterial oxygen saturation between 35 and 45%), pulmonary arterial pressure increased by 48% (p < 0.01), pulmonary vascular resistance increased by 74% (p < 0.01), and both systemic arterial pressure and systemic vascular resistance decreased by 38 and 31%, respectively (p < 0.01). The animals were then giving varying concentrations of inhaled nitric oxide between 5 and 80 parts per million in random order. All concentrations of nitric oxide were associated with a rapid decrease in pulmonary arterial pressure and pulmonary vascular resistance (p < 0.001). Cardiac index increased (p < 0.001) and systemic vascular resistance significantly decreased (p = 0.01) with all doses of inhaled nitric oxide. The ratio of pulmonary to systemic vascular resistance decreased with all levels of inhaled nitric oxide (p < 0.001). For all of the above observations there was no significant difference noted between the varying doses of nitric oxide. The time course of the pulmonary arterial pressure response to nitric oxide was approximately twice as fast as that seen with the inhalation of 100% oxygen (10, 50, 90% responses of 4.1, 8.8, 88.6 versus 6.7, 51.9, 197 s, respectively; p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Lewis-Base Adducts of Group 11 Metal(I) Compounds. XLVI. Synthesis and Conformational Systematics of Some Novel Polymeric Adducts of Pyridine-4-carbonitrile With Copper(I) Halides

The isolation and structural characterization of 1 : 1 adducts of copper(1) chloride (1) and bromide (2) with pyridine-4-carbonitrile (L) is described; crystals of the two complexes are isomorphous (monoclinic, P21/c, a ≈ 3.9, b ≈ 14.7, c ≈ 13.0 � , β ≈ 96°, Z 4; R0.047, 0.063 for No 630, 707 'observed' reflections respectively). Unlike the 1 : 1 adducts with the parent pyridine and benzonitrile ligands which are 'stair' polymers, these complexes comprise 'split-stair' strands woven into a two-dimensional sheet by crosslinking ambidentate ligands. Cu-N ( nitrile ) (1.942(9), 1.96(1) � ) are appreciably shorter than Cu-N (pyridine) (2.066(8), 2.04(1) � ), as in the parent base complexes. The two Cu-X are similar in each case: 2.336(6), 2.366(3) � (CI); 2.460(3), 2.486(3) � (Br). The iodide adduct (3) isolated is of novel stoichiometry (Cul : L, 4 : 5) (monoclinic, P21/c; a 10.140(5), b 12.214(6), c 15.157(8) � , β 99.99(4)° Z 2; R 0.048, No 2416). It is a linear polymer, comprising tetranuclear Cu414L4 'step' units, crosslinked across inversion centres by disordered ambidentate ligands.

Pneumatosis cystoides intestinalis. Presentation as an acute abdomen

It is rare for pneumatosis cystoides intestinalis to give rise to abdominal pain. We report a patient with signs and symptoms of a perforated viscous in whom abdominal exploration was negative, but in whom biopsy of various intraabdominal cystic structures revealed only pneumatosis cystoides intestinalis.

The management of severely comminuted fractures of the femoral shaft, using the external fixator

Fractures of the femoral shaft are often treated by an established method of internal fixation, such as a medullary nail or a plate and screws, to obviate the many disadvantages of traction and prolonged rest in bed. Fractures of the femoral shaft which are severely comminuted and open are usually unsuitable for internal fixation. Between July 1981 and March 1983 we treated seven patients with severely comminuted fractures of the femoral shaft (of which three were open), using the ASIF tubular external fixator system or the Wagner apparatus. The technique of application of the external fixator is important and is described. When correctly applied, the knee's movement was not restricted and few complications were experienced. All the fractures united within 8 months in a good position without shortening, and none required an additional operation. The use of the external fixator in these patients reduced their time in the hospital and facilitated their postoperative rehabilitation by allowing uncomplicated healing of a complicated fracture.

Actin filaments and acetylcholine receptor clusters in embryonic chick myotubes

The tumor-promoting drug 4 beta-phorbol 12-myristate 13-acetate (TPA) causes the loss of myofibrils in primary cultures of chick embryonic myotubes [9]. When myofibrils in chick myotubes are dispersed by TPA treatment (5 X 10(-8) M), there remains a class of non-myofibrillar actin filaments that are sensitive to subsequent breakdown by cytochalasin D. Microfilament bundles in fibroblasts in the same cultures seem unaffected by this TPA treatment, but are also broken down by cytochalasin D (0.2 micrograms/ml); this dose has little effect on myofibrils. We have previously shown that treatment of chick myotubes with cytochalasins would destabilize clusters of acetylcholine receptors (AChRs) [6]. In order to further examine the relationship between actin filaments and cell surface AChRs, we have used the receptor-specific ligand alpha bungarotoxin (a-BGT) to study the fate of AChR clusters in drug-treated and control myotubes. Cells treated with TPA showed no loss in the number of receptor clusters present on their surface. However, if these cells were also treated with cytochalasin D, cluster number was reduced to approximately the same value as seen for cytochalasin treatment alone (50% of the control value). These results suggest that the cytoskeletal link to these cell surface receptors is not mediated by attachment to the alpha actin-containing myofibrils, but rather clustered AChRs are stabilized by a class of non-myofibrillar actin filaments.