Assessment of revascularization impact on microvascular oxygenation and perfusion using spatial frequency domain imaging

The microvasculature (with vessels <100 μm in diameter) plays a crucial role in tissue oxygenation, perfusion and wound healing in the lower limb. While this holds clinical significance, microvasculature evaluation in the limbs is not a standard practice. Surgical interventions focus on reestablishing blood flow in larger vessels affected by the peripheral artery disease (PAD). Nevertheless, the impact of revascularization on tissue oxygenation and perfusion in severe microvascular disease (MVD) is still unknown. We present the cases of two patients who underwent surgical revascularization for peripheral blood flow with different outcomes. Patient A had PAD, while B had PAD, severe MVD and a non-healing wound. Although both showed improvements in ankle-brachial index post-op, spatial frequency domain imaging metrics (which measure microvascular oxygenation and perfusion) remained unchanged in B, indicating a potential gap in assessing the surgical efficacy in MVD using ankle brachial index and emphasizing microcirculation evaluation in optimizing wound healing outcomes.

Considering Inelasticity in the Real-Time Monitoring of Particle Size for Twin-Screw Granulation via Acoustic Emissions

A recently developed process analytical technology (PAT) using artificial intelligence to form the framework of its model, combining frequency-domain acoustic emissions (AE) and elastic impact mechanics to accurately predict complex particle size distributions (PSD) in real-time. This model was modified in this study to give more accurate predictions for the more highly cohesive granules typical of pharmaceutical solid oral dosage formulations. AE spectra were collected from the granulated impacts of various formulations with ranging characteristics from largely elastic to highly inelastic collision responses. A viscoelastic (Hertzian spring-dashpot) and elastoplastic (Walton-Braun) contact force model were compared to understand how these different micro-mechanical approaches would affect the prediction accuracy of particle sizes relevant to granulation. Retraining the artificial intelligence model with the Walton-Braun transformation and a more comprehensive dataset of AE spectra spanning a broad range of granulated formulations showed the prediction error drop to as low as 2% compared to the original elastic version showing errors as large as 18.6% with representative formulations of the industry. The improved PAT shows good applicability to monitoring bimodal PSD that are typical of continuous twin-screw granulation.

Stratification of Microvascular Disease Severity in the Foot Using Spatial Frequency Domain Imaging

BACKGROUND

Microvascular disease (MVD) describes systemic changes in the small vessels (~100 um diameter) that impair tissue oxygenation and perfusion. MVD is a common but poorly monitored complication of diabetes. Recent studies have demonstrated that MVD: (i) is an independent risk factor for ulceration and amputation and (ii) increases risk of adverse limb outcomes synergistically with PAD. Despite the clinical relevance of MVD, microvascular evaluation is not standard in a vascular assessment.

METHODS

We evaluated 299 limbs from 153 patients seen clinically for possible lower extremity PAD. The patients were assessed by ankle brachial index (ABI), toe brachial index (TBI), and spatial frequency domain imaging (SFDI). These measurements were evaluated and compared to patient MVD status, defined by clinical diagnoses of (in ascending order of severity) no diabetes; diabetes; diabetes + neuropathy; diabetes + neuropathy + retinopathy.

RESULTS

SFDI-derived parameters HbT1 and StO2 were significantly different across the MVD groups (P < .001). A logistic regression model based on HbT1 and StO2 differentiated limbs with severe MVD (diabetes+neuropathy+retinopathy) from the larger group of limbs from patients with only diabetes (P = .001, area under the curve = 0.844). Neither ABI nor TBI significantly differentiated these populations.

CONCLUSIONS

Standard assessment of PAD using ABI and TBI are inadequate for detecting MVD in at-risk populations. SFDI-defined HbT1 and StO2 are promising tools for evaluating MVD. Prospective studies with wound-based outcomes would be useful to further evaluate the role MVD assessment could play in routine clinical evaluation of patients at risk for lower extremity complications.

Orthogonal SARS-CoV-2 Serological Assays Enable Surveillance of Low-Prevalence Communities and Reveal Durable Humoral Immunity

We conducted a serological study to define correlates of immunity against SARS-CoV-2. Compared to those with mild coronavirus disease 2019 (COVID-19) cases, individuals with severe disease exhibited elevated virus-neutralizing titers and antibodies against the nucleocapsid (N) and the receptor binding domain (RBD) of the spike protein. Age and sex played lesser roles. All cases, including asymptomatic individuals, seroconverted by 2 weeks after PCR confirmation. Spike RBD and S2 and neutralizing antibodies remained detectable through 5-7 months after onset, whereas α-N titers diminished. Testing 5,882 members of the local community revealed only 1 sample with seroreactivity to both RBD and S2 that lacked neutralizing antibodies. This fidelity could not be achieved with either RBD or S2 alone. Thus, inclusion of multiple independent assays improved the accuracy of antibody tests in low-seroprevalence communities and revealed differences in antibody kinetics depending on the antigen. We conclude that neutralizing antibodies are stably produced for at least 5-7 months after SARS-CoV-2 infection.

Detection, prevalence, and duration of humoral responses to SARS-CoV-2 under conditions of limited population exposure

We conducted an extensive serological study to quantify population-level exposure and define correlates of immunity against SARS-CoV-2. We found that relative to mild COVID-19 cases, individuals with severe disease exhibited elevated authentic virus-neutralizing titers and antibody levels against nucleocapsid (N) and the receptor binding domain (RBD) and the S2 region of spike protein. Unlike disease severity, age and sex played lesser roles in serological responses. All cases, including asymptomatic individuals, seroconverted by 2 weeks post-PCR confirmation. RBD- and S2-specific and neutralizing antibody titers remained elevated and stable for at least 2-3 months post-onset, whereas those against N were more variable with rapid declines in many samples. Testing of 5882 self-recruited members of the local community demonstrated that 1.24% of individuals showed antibody reactivity to RBD. However, 18% (13/73) of these putative seropositive samples failed to neutralize authentic SARS-CoV-2 virus. Each of the neutralizing, but only 1 of the non-neutralizing samples, also displayed potent reactivity to S2. Thus, inclusion of multiple independent assays markedly improved the accuracy of antibody tests in low seroprevalence communities and revealed differences in antibody kinetics depending on the viral antigen. In contrast to other reports, we conclude that immunity is durable for at least several months after SARS-CoV-2 infection.

Impact of non-binder ingredients and molecular weight of polymer binders on heat assisted twin screw dry granulation

Two grades of commercial AFFINISOL™ HPMC HME were used as polymer binders to explore the influence of polymer viscosity and concentration on a novel heat assisted dry granulation process with a twin screw extruder. Contributions of other non-binder ingredients in the formulations were also studied for lactose, microcrystalline cellulose and an active pharmaceutical ingredient of caffeine. As sensitive indicators of processing conditions that expose the drug to high internally generated heat, dehydration of α-lactose monohydrate and polymorphic transformation of caffeine were monitored by differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD). Additionally, any decomposition of caffeine was determined by high-performance liquid chromatography (HPLC). Granular samples were characterized by particle size, circularity, fracture strength and their temperature on the exit of extruder. Higher screw speed and lower feed rate were found to help particles agglomerate by allowing feed particles a greater opportunity to increase in temperature. Lower binder molecular weight and higher binder concentration enable granules to build stronger strength and thereby lead to higher particle size. This new twin screw dry granulation was demonstrated as offering advantages over conventional hot melt granulation by minimizing thermal degradation of the tested ingredients.

Clinical assessment to determine the risk of bowel cancer using Symptoms, Age, Mass and Iron deficiency anaemia (SAMI)

BACKGROUND

The aim of this study was to identify characteristics with independent predictive value for bowel cancer for use in the clinical assessment of patients attending colorectal outpatient clinics.

METHODS

This was a 22-year (1986-2007) retrospective cohort analysis of data collected prospectively from patients who attended colorectal surgical outpatient clinics in Portsmouth. The data set was split randomly into two groups of patients to generate and validate a predictive model. Multivariable logistic regression was used to create and validate a system to predict outcome. Receiver operating characteristic (ROC) curves and Hosmer-Lemeshow test were used to evaluate the model's predictive capability. The likelihood of bowel cancer was expressed as the odds ratio (OR).

RESULTS

Data from 29 005 patients were analysed. Discrimination of the model for bowel cancer was high in the development (C-statistic 0·87, 95 per cent c.i. 0·85 to 0·88) and validation (C-statistic 0·86, 0·84 to 0·87) groups. The most important co-variables in the final model were: age (OR 3·17-27·10), rectal (OR 31·48) or abdominal (OR 1·83-8·45) mass, iron deficiency anaemia (IDA) (OR 4·42-8·38), rectal bleeding and change in bowel habit in combination (OR 5·37), change in bowel habit without rectal bleeding, with or without abdominal pain (OR 2·12-2·52), and rectal bleeding with no perianal symptoms and without change in bowel habit (OR 2·91). Some 91·5 per cent of bowel cancers presented with these characteristics, 40·4 per cent with a mass and/or IDA. In patients with at least one of these characteristics the overall risk of having cancer was 10·0 (range 6·5-50·4) per cent, compared with 1·1 (0·3-2·3) per cent in patients without them.

CONCLUSION

A clinical assessment that systematically identifies or excludes four symptom-age combinations, a mass and IDA (SAMI) stratifies patients as having a low and higher risk of having bowel cancer. This could improve patient selection for referral and investigation.

"Rolling" phenomenon in twin screw granulation with controlled-release excipients

The developed knowledge regarding use of twin screw granulators for continuous wet granulation has been primarily limited to immediate release formulations in the literature. The present study highlights an issue previously unreported for wet granulation with twin screw extruders when using formulations containing controlled-release (CR) excipients. Long (3-10 mm), twisted noodle-like granules can be produced in the presence of these excipients that are difficult to control and are anticipated to create complications in downstream unit operations to the granulator. Working with two different CR excipients, METHOCEL™ K4M and Kollidon® SR, each blended at different ratios with a mixture of 80% α-lactose monohydrate/20% microcrystalline cellulose, these unique particles were found to be produced in the conveying elements of the extruder, arising from a rolling action at the top of the screw flights. The CR excipients adhesively strengthen the wetted mass, forming this undesired granule shape such that they persisted to the exit of the machine; the shape appeared most strongly affected by screw speed, producing particles of higher aspect ratio as speed was increased. Adjusting the concentration of these CR excipients in the formulation, the flow rate or the type of compression element used in the screws proved ineffective in controlling the problem. Rather, a re-design of the extruder screws was required to prevent generation of these extended-form granules.

Influence of filler selection on twin screw foam granulation

The influence of filler selection in wet granulation was studied for the novel case where the binder is delivered as an unstable, semi-rigid aqueous foam to an extrusion process. The work primarily examined the impact of differing concentrations of microcrystalline cellulose (Avicel PH® 101) in a formulation with spray-dried α-lactose monohydrate (Flowlac® 100) in regards to wetting and granule nucleation for this relatively new technique known as continuous foam granulation. Foam stability was varied within the work to change its drainage and coarsening behavior atop these powder excipients, by use of different foamable binding agents (METHOCEL™ F4 PLV and METHOCEL™ Premium VLV) as well as by adjusting the foam quality. A static bed penetration test was first used to study the foam behavior in wetting these powders without the processing constraints of an extruder which limit possible liquid-to-solids ratios as well as introduce shear which may complicate interpretation of the mechanism. The test found that the penetration time to saturate these powders decreased as their water absorption capacity increased which in turn decreased the size of the formed nuclei. Differences in the stability of the foamed binder had minimal influence on these attributes of wetting despite its high spread-to-soak behavior. The size of granules produced by extrusion similarly demonstrated sensitivity to the increasing water absorption capacity of the filler and little dependency on foam properties. The different liquid-to-solids ratios required to granulate these different formulations inside the extruder highlighted an evolving concept of powder lubricity for continuous foam granulation.

Low rates of local recurrence after surgical resection of rectal cancer suggest a selective policy for preoperative radiotherapy

AIM

Preoperative short-course radiotherapy (SCRT) is increasingly recommended to reduce local recurrence after surgery for rectal cancer. Its avoidance may be beneficial, however, if the risk of local recurrence is low. We report a single centre experience which suggests that selective rather than uniform use of SCRT may be the best approach.

METHOD

Analysis was carried out on a prospectively collected unselected series of 1606 patients with rectal cancer treated in one centre. Follow-up was 97% complete. SCRT was performed selectively and all patients had a mesorectal excision.

RESULTS

Among 940 patients undergoing a potentially curative major resection the operative mortality was 4.6%, the permanent stoma rate 23% and the crude 5-year survival 61%. The local recurrence rate after curative anterior resection was 2.9% and 7.7% after abdominoperineal excision. The overall local recurrence rate after a potentially curative major resection was 4.0%.

CONCLUSION

The routine use of preoperative radiotherapy for rectal cancer is probably not justified where local recurrence after curative rectal resection is uncommon.

Is earlier referral and investigation of bowel cancer patients presenting with rectal bleeding associated with better survival?

AIM

This study was carried out to determine whether rectal bleeding is related to stage of bowel cancer and whether earlier diagnosis and treatment are associated with improved survival.

METHOD

Eight hundred and forty-five patients were identified in the Wessex Bowel Cancer Audit (1991-1994). Presenting symptoms were identified from case notes. Outcome measures included 5-year survival, Dukes' stage, metastatic disease at surgery and time from onset of symptoms to treatment, in patients presenting with rectal bleeding or other symptoms and signs.

RESULTS

Six hundred and seventy-six (80%) of 845 patient case notes were reviewed. Of these, 408 (60.4%) patients had rectal or sigmoid cancer, and 255 (62.5%) of these 408 patients, who presented with rectal bleeding, had significantly earlier stage disease than those with a change in bowel habit and/or abdominal pain (Dukes' stage A: 23.1%vs 3.6%; Dukes' stage D: 14.5%vs 23.4%; P < 0.001), fewer metastases visible at surgery (14.9%vs 22.6%; P < 0.001) and significantly better 5-year survival (54.8%vs 40.9%; P < 0.001). There was no further significant improvement in 5-year survival in patients treated within 6 months of the onset of symptoms (55.1%vs 53.5%). Hazard ratios showed that 5-year survival was independently associated with age, Dukes' stage and emergency treatment, but not with rectal bleeding, change in bowel habit, abdominal pain or delay in treatment.

CONCLUSION

Bowel cancer patients presenting with rectal bleeding had earlier stage disease and significantly better survival than patients presenting with a change in bowel habit or abdominal pain. There was no reduction in 5-year survival in those patients who had a delay in treatment for > 6 months from the onset of symptoms.

Cleft closure for the treatment of pilonidal sinus disease

AIM

Treatments for pilonidal sinus disease are numerous and prone to failure. In complex disease, the morbidity is high. In contrast with complex operations, the cleft closure procedure can be done simply and successfully with better cosmetic results. We present the results of a single-centre experience of this procedure.

METHOD

One hundred and fifty patients had the operation; most were treated as a day case and many were operated under local anaesthetic.

RESULTS

Primary healing occurred in 83 (60%) of 139 patients. Recurrences requiring surgery have been seen in 5.3%. The long-term cosmetic appearance has been noted to approach normality.

CONCLUSION

Cleft closure is a simple and highly effective operation to treat recurrent or extensive pilonidal sinus disease.

Simple day-case surgery for pilonidal sinus disease

BACKGROUND

Pilonidal disease is a common and usually minor disease. Although wide excisional surgery has been common practice, there are more simple alternatives. This review focused on the aetiology and management of pilonidal disease.

METHODS

A comprehensive review of the literature on pilonidal disease was undertaken. MEDLINE searches for all articles listing pilonidal disease (1980-2010) were performed to determine the aetiology and results of surgical and non-surgical treatments. Single papers describing new techniques or minor modifications of established techniques were excluded. Further articles were traced through reference lists.

RESULTS

Patients with minimal symptoms and those having drainage of a single acute abscess can be treated expectantly. Non-surgical treatments may be of value but their long-term results are unknown. There is no rational basis or need for wide excision of the abscess and sinus. Simple removal of midline skin pits, the primary cause of pilonidal disease, with lateral drainage of the abscess and sinus is effective in most instances. Hirsute patients with extensive primary disease and deep natal clefts, or with recurrent disease and unhealed midline wounds, may also require flattening of the natal cleft with off-midline skin closure. These more conservative procedures are usually done as a day case, require minimal care in the community and are associated with a rapid return to work. They also avoid the occasional debilitating complications of surgical treatment.

CONCLUSION

Simple day-case surgery to eradicate midline skin pits without wide excision of the abscesses and sinus is rational, safe and effective for patients with pilonidal sinus disease.

Earlier diagnosis and treatment of symptomatic bowel cancer: can it be achieved and how much will it improve survival?

AIM

To determine current delays in diagnosis and treatment of bowel cancer, when and why they occur, and what effect they have on survival.

METHOD

A detailed review of the literature based on the development of the GP referral guidelines in 2000.

RESULTS

There is no evidence of a reduction in the delay to diagnosis and treatment of bowel cancer over the last 60 years. There is no strong theoretical basis for a benefit from earlier diagnosis of symptomatic bowel cancer and this is consistent with observational studies.

CONCLUSION

Campaigns to earlier diagnose bowel cancer will not be successful unless new strategies are developed. There is substantial evidence that earlier diagnosis of symptomatic bowel cancer will not improve survival in the majority of patients. However as excessive delays still occur in some patients it is reasonable to continue to aim to diagnose and treat all bowel cancer within 6 months of the onset of symptoms with an overall median of 3-4 months.

ApoE polymorphisms and diarrheal outcomes in Brazilian shanty town children

A series of studies have shown that the heavy burdens of diarrheal diseases in the first 2 formative years of life in children living in urban shanty towns have negative effects on physical and cognitive development lasting into later childhood. We have shown that APOE4 is relatively common in shanty town children living in Brazil (13.4%) and suggest that APOE4 has a protective role in cognitive development as well as weight-for-height in children with heavy burdens of diarrhea in early childhood (64/123; 52%), despite being a marker for cognitive decline with Alzheimer's and cardiovascular diseases later in life. APOE2 frequency was higher among children with heaviest diarrhea burdens during the first 2 years of life, as detected by PCR using the restriction fragment length polymorphism method, raising the possibility that ApoE-cholesterol balance might be critical for growth and cognitive development under the stress of heavy diarrhea burdens and when an enriched fat diet is insufficient. These findings provide a potential explanation for the survival advantage in evolution of genes, which might raise cholesterol levels during heavy stress of diarrhea burdens and malnutrition early in life.

The National Bowel Cancer Audit: the risks and benefits of moving to open reporting of clinical outcomes

BACKGROUND

The government's proposals to openly report clinical outcomes poses challenges to the National Bowel Cancer Audit now funded by the UK department of health.

AIM

To identify the benefits and risks of open reporting and to propose ways the risks might be minimized.

METHODS

A review of the literature on clinical audit and the consequences of open reporting.

RESULTS

There are significant potential benefits of a national audit of bowel cancer including protecting patients from sub-standard care, providing clinicians with externally validated evidence of their performance, outcome data for clinical governance and evidence that increases in government expenditure are achieving improvements in survival from bowel cancer. These benefits will only be achieved if the audit captures most of the cases of bowel cancer in the UK, the data collected is complete and accurate, the results are risk adjusted and these are presented to the public in a way that is fair, clear and understandable. Involvement of clinicians who have confidence in the results of the audit and who actively compare their own results against a national standard is essential. It is suggested that a staged move to open reporting should minimise the risk of falsely identifying an outlying unit.

CONCLUSION

The fundamental aim of the National Bowel Cancer Audit is the pursuit of excellence by identification and adoption of best practice. This could achieve a continuous improvement in the care of all patients with bowel cancer in the UK. The ACPGBI suggests a safer way of transition to open reporting to avoid at least some of its pitfalls.

In situ x-ray diffraction studies of alkyl quaternary ammonium montmorillonite in a CO(2) environment

An in situ study was conducted using an x-ray diffractometer and a specially designed high pressure cell to examine the effects of carbon dioxide at different pressures and temperatures on three different modified montmorillonite species. These organoclays possessed organic pillars of quaternary ammonium surfactant with either one, two, or three long (C(16)-C(18)) alkyl chains attached to expand the galleries of the clay mineral. The three clay species were tested between 50 degrees C and 200 degrees C with carbon dioxide pressures between 0.1 and 8.4 MPa. Under these conditions, the three organoclays exhibited marked differences in their basal spacing depending on the surfactant used. The physical state of the intercalated surfactant was found to be of critical importance, with no changes in basal spacing noted until the organic component began to melt, in spite of CO(2) being present. A pressure effect was also noted which delayed melting of the surfactants as the pressure of the system increased. In all cases, further cation exchange with residual sodium cation present in the galleries was observed in the presence of CO(2) and above the melting state of the surfactant. The study included examination of the effect of rapid depressurization on the clay structure, which produced only a small change in basal spacing.

Disease stage and psychosocial outcomes in colorectal cancer

OBJECTIVE

Disease stage is a strong predictor of cancer survival and is therefore assumed to influence psychosocial outcomes. However, existing findings are inconsistent, perhaps reflecting limited sample sizes, especially among patients with advanced disease. There has also been an emphasis on breast cancer, resulting in a focus on outcomes among women. The present study investigated associations between disease stage and psychosocial wellbeing in 128 patients (52% male, 48% female) diagnosed with colorectal cancer.

METHOD

Patients diagnosed within the past year in a single hospital were invited to participate in a questionnaire study and give permission for staging information to be obtained from their medical records. The questionnaire included measures of anxiety, depression, quality of life, social support, social difficulties and quality of medical interactions.

RESULTS

Patients with more advanced disease were more anxious (P < 0.01) and depressed (P < 0.001), perceived their social support as lower (P < 0.01), and had a worse quality of life (P < 0.01). Women with advanced disease had more severe colorectal symptoms (P < 0.01), and worse physical (P < 0.01) and emotional (P < 0.05) quality of life than men.

CONCLUSION

Patients with advanced colorectal cancer have unmet psychosocial needs. Women may be more strongly affected by advanced disease than men.

Flexible sigmoidoscopy and whole colonic imaging in the diagnosis of cancer in patients with colorectal symptoms

BACKGROUND

The aim was to identify the patients with colorectal symptoms most likely to benefit from whole colonic imaging (WCI) to diagnose colorectal cancer and those for whom flexible sigmoidoscopy (FS) may be initially sufficient.

METHODS

This prospective observational study (16 years) included 16 433 newly referred patients with symptoms or signs of colorectal cancer.

RESULTS

Colorectal cancer was diagnosed in 946 patients (diagnostic yield 5.8 per cent), 815 (86.2 per cent) in the rectum or sigmoid (distal) and 131 (13.8 per cent) in the proximal colon. Some 15 829 patients (96.3 per cent) presented with symptoms alone (without iron deficiency anaemia or abdominal mass). Of 787 cancers in these patients, 750 (95.3 per cent) were distal. The prevalence of proximal cancer above and below the age of 60 years was 0.4 per cent (33 of 8249) and 0.1 per cent (four of 7580) respectively. Of 16 256 patients having FS, 5665 (34.8 per cent) had WCI. Of the other 10 591, five subsequently presented with proximal cancers. FS missed ten (1.3 per cent) of 796 cancers.

CONCLUSION

Patients with iron deficiency anaemia or a mass require WCI. However, in patients with symptoms alone, FS detects 95 per cent of cancers, and the diagnostic yield of WCI after FS is very low. Alternative management strategies need to be developed to avoid unnecessary investigations in this low-risk group.

Neural correlates of MDMA ("Ecstasy")-induced social interaction in rats

The popular drug 3,4 methylenedioxymethamphetamine (MDMA, "Ecstasy", "the Love Drug") produces feelings of love and closeness in humans and induces analogous prosocial and antiaggressive effects in laboratory animals. Here we examined the specific brain regions that may be involved in these prosocial effects. Male Wistar rats were pretreated with a moderate dose of MDMA (5 mg/kg) or vehicle and then either kept alone in a familiar test chamber for 60 min (groups MDMA-ALONE and VEHICLE-ALONE) or allowed to engage in social interaction in the familiar test chamber with an unfamiliar same-sex conspecific for 60 min (groups MDMA-SOCIAL and VEHICLE-SOCIAL). Rats in the MDMA-SOCIAL group showed much greater overall social interaction than rats in the VEHICLE-SOCIAL group, with microanalysis revealing increased general investigation of other rats but decreased anogenital sniffing. Analysis of neural activation across 39 brain regions using Fos immunohistochemistry showed the following results: (1) VEHICLE-SOCIAL and VEHICLE-ALONE groups did not differ in Fos expression, indicating that a social context per se did not affect Fos expression, (2) MDMA-treated groups showed significantly increased Fos expression relative to VEHICLE treated groups in 30 brain regions, (3) the MDMA-SOCIAL group showed augmented Fos expression relative to the MDMA-ALONE group in six brain regions including the caudate-putamen (medial), medial preoptic area, paraventricular thalamic nucleus, central amygdala, ventromedial hypothalamic nucleus, and the medial amygdala (posterodorsal), and (4) the MDMA-SOCIAL group (but not the MDMA-ALONE group) showed augmented Fos expression relative to the VEHICLE groups in the nucleus accumbens, ventral tegmental area and periaqueductal grey. These results indicate that a moderate dose of MDMA given in a social context causes considerably greater brain activation than the same dose given to solitary rats. This activation involves specific neural circuits that are known to regulate affiliative behavior, perhaps by modulating the incentive value of social stimuli. A possible role for the neuropeptide oxytocin in mediating the prosocial effects of MDMA is discussed.

Predictive value of common symptom combinations in diagnosing colorectal cancer

Background

This study compared the diagnostic values of age and single symptoms of colorectal cancer with those of age and symptom combinations.

Methods

Consecutive patients with lower gastrointestinal symptoms referred to a surgical clinic over a 12-year period were studied prospectively. The diagnostic value of age and common symptoms of bowel cancer, individually and in combination, was determined by measuring positive predictive value, sensitivity and specificity.

Results

In total, 467 (5·5 per cent) of 8529 patients had colorectal cancer. Symptom combination analyses showed that patients presenting with rectal bleeding and change in bowel habit without anal symptoms had the highest risk of cancer. Those with rectal bleeding and perianal symptoms without change in bowel habit were at the lowest risk of having cancer. Symptom subgroups defined by age had positive predictive values for cancer that varied from less than 1 to 35 per cent.

Conclusion

Symptom combinations defined by age have greater diagnostic value than single symptoms alone.

A role for oxytocin and 5-HT(1A) receptors in the prosocial effects of 3,4 methylenedioxymethamphetamine ("ecstasy")

The drug 3,4 methylenedioxymethamphetamine (MDMA; ecstasy) has a widely documented ability to increase feelings of love and closeness toward others. The present study investigated whether oxytocin, a neuropeptide involved in affiliative behavior, may play a role in this effect. A moderate (5 mg/kg, i.p.) dose of MDMA increased social interaction in male Wistar rats, primarily by increasing the amount of time rats spent lying adjacent to each other. MDMA (5 mg/kg) activated oxytocin-containing neurons in the supraoptic and paraventricular nuclei of the hypothalamus, as shown by Fos immunohistochemistry. MDMA (5 mg/kg i.p.) also increased plasma oxytocin levels and this effect was prevented by pre-treatment with the 5-HT(1A) antagonist N-[2-[4-(2-methyoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide maleate salt (WAY 100,635; 1 mg/kg i.p.). The oxytocin receptor antagonist tocinoic acid (20 microg, i.c.v.) had no effect on social behavior when given alone but significantly attenuated the facilitation of social interaction produced by MDMA (5 mg/kg). The 5-HT(1A) agonist 8-hydroxy-2-(di-n-propylamino)-tetraline) (8-OH-DPAT, 0.25 mg/kg, i.p.) increased social behavior in a similar way to MDMA and this effect was also significantly attenuated by tocinoic acid. Taken together, these results suggest that oxytocin release, stimulated by MDMA through 5-HT(1A) receptors, may play a key role in the prosocial effects of MDMA and underlie some of the reinforcing effects of the drug.

Social deprivation and outcomes in colorectal cancer

Background

The aim of this study was to examine the influence of social deprivation on postoperative mortality and length of stay in patients having surgery for colorectal cancer.

Methods

Data were extracted from the Association of Coloproctology of Great Britain and Ireland database of patients presenting between April 2001 and March 2002. The effect of social deprivation, measured by the Townsend score, on 30-day postoperative mortality and length of stay was evaluated by two-level hierarchical regression analysis.

Results

A total of 7290 (86·8 per cent) patients underwent surgery. Operative mortality was 6·7 per cent and median length of stay 11 days. Deprivation indices were significantly higher in patients with Dukes' ‘D’ cancers, undergoing emergency surgery and with higher American Society of Anesthesiologists (ASA) grades (P &lt; 0·005). Worsening deprivation was associated with higher operative mortality and longer stay (P = 0·014). For each unit increase in deprivation, there was 2·9 (95 per cent confidence interval 0·5 to 5·2) per cent increase in 30-day mortality. On multifactorial analysis, social deprivation was an independent predictor of length of stay, but its effect on operative mortality was explained by differences in ASA grade, operative urgency and Dukes' classification.

Conclusion

Social deprivation was an independent risk factor of postoperative length of stay and associated with higher postoperative mortality. These results have important implications for risk modelling of postoperative outcomes.

Sub-specialization in general surgery: the problem of providing a safe emergency general surgical service

BACKGROUND

The increasing subspecialization of general surgeons in their elective work may result in deskilling and create problems in providing expert care for emergency cases. To evaluate the size of the problem this study determined how often complex emergency surgical cases are treated by general surgeons working outside their own elective subspecialty.

METHOD

In a district general hospital in the south of the UK serving a population of 550 000 where there is almost complete subspecialization within general surgery, 1554 patients having emergency general surgical operations were studied in a one-year review. The time an operation occurred, the seniority of the operating surgeon, the subspecialty interest of the consultant responsible for the case compared with the specialist nature of the operation was determined.

RESULTS

Of 1554 patients having emergency general surgical operations, 23% (352/1554) were of a high category of complexity. Ninety were vascular procedures and were dealt with by specialist vascular surgeons on a separate rota. Of the remaining 262 operations, 78 (30%) did not match the subspecialty of the consultant surgeon responsible for their care; 56 (72%) of these occurred out of hours of which 14 (18%) had a consultant surgeon present and scrubbed in the theatre; one per month of the study. Seventy-three percent (57/78) of these were complex colorectal operations.

CONCLUSION

The mismatch between the subspecialist elective interests of the consultant general surgeon and out of hours specialist major surgery needing consultant involvement occurred infrequently, and was mainly due to major lower gastrointestinal cases managed by upper gastrointestinal and breast surgeons. This has important implications for the future training of general surgeons and the provision of an emergency nonvascular general surgical service.

Cleft closure for the treatment of unhealed perineal sinus

OBJECTIVE

Despite improvements in surgical practice, persistent perineal wound sinus is still a common complication after proctectomy. This study presents the success of a modified cleft closure technique in dealing with this problem.

METHODS

From May 1997 patients with a persistent perineal sinus after surgery underwent a cleft closure - similar to that performed for patients with pilonidal sinus disease.

RESULTS

Eight patients (6 male, 2 female) with an average age of 52 years underwent a cleft closure for a persistent perineal sinus after surgery. Four patients had undergone a proctocolectomy (ulcerative colitis), 2 an abdominoperineal excision of the rectum (adenocarcinoma) and 2 a proctectomy (1 Crohn's disease, 1 complication of diverticular disease). Symptoms had been present for an average of 41 months (range 5-152 months) and 3 patients had undergone other procedures attempted previously to deal with the problem. The first three patients had the procedure as an inpatient with an average stay of 4.7 days. The next 5 patients had the procedure as a day case (2 local anaesthetic, 3 general anaesthetic). Two patients developed a postoperative wound infection and all but one wound had healed completely by 8 weeks. In this patient the procedure was repeated to achieve healing. There was no other associated morbidity and no postoperative deaths. There have been no recurrences to date.

CONCLUSION

Modified cleft closure for persistent perineal sinus is a simple procedure with low morbidity that can be performed under local anaesthetic in the day surgery unit.

Comparison of circumferential margin involvement between restorative and nonrestorative resections for rectal cancer

OBJECTIVE

To study circumferential margin involvement (CMI) in patients undergoing restorative, compared with nonrestorative, surgery for rectal cancer.

DATA SOURCE

Descriptive multicentre study, using routinely collected clinical data from the Association of Coloproctology of Great Britain and Ireland (ACPGBI) Bowel Cancer Audit database. The study encompassed 1403 newly diagnosed patients with rectal cancer undergoing either restorative (anterior resection (AR)), or nonrestorative (abdominoperineal excision of rectum (APER) or Hartmann's procedure), surgery. Operations were carried out in 39 hospitals during a variable period between April 1999 to March 2002. A logistic regression analysis was used to control for variables associated with circumferential margin involvement.

RESULTS

One thousand and thirty-six patients satisfied the inclusion criteria. The average CMI was 12.5% (range 0-33.3% between hospitals). CMI for anterior resection was 7.5% (n = 629) compared with a CMI of 16.7% for APER (n = 306) and a CMI of 31.7% for Hartmann's procedure (n = 101); P < or = 0.001. CMI for patients undergoing curative surgery was 7.1% (423 anterior resections, CMI 3.8% (n = 16); 181 APER, CMI 13.3% (n = 24); 29 Hartmann's procedure, CMI 17.2%). On multivariate analysis, having controlled for Dukes' stage and operative intent, the CMI was significantly different between APER and AR (odds ratio 3.3, 95%CI 2.0-5.4), but less so between Hartmann's procedure and AR (odds ratio 2.2, 95%CI 1.1-4.2).

CONCLUSIONS

APER is associated with a significantly higher CMI than anterior resection. Attention to surgical technique, with a wide perineal dissection and the use of pre-operative adjuvant therapy, may reduce CMI in patients undergoing APER.

Prevalence of Escherichia coli and Salmonella spp. in street-vended food of open markets (tianguis) and general hygienic and trading practices in Mexico City

Street-vendors in Mexico City provide ready-to-eat food to a high proportion of the inhabitants. Nevertheless, their microbiological status, general hygienic and trading practices are not well known. During spring and summer 2000, five tianguis (open markets) were visited and 48 vendors in 48 stalls interviewed. A total of 103 taco dressings were sampled for E. coli and Salmonella spp.: 44 (43%) contained E. coli and 5 (5%) Salmonella (2 S. Enteritidis phage type 8, 1 S. Agona, 2 S. B group). Both E. coli and salmonellas were isolated from three samples. Of Salmonella-positive stalls 80% (4/5) had three or more food-vendors and 80% of vendors were males, compared with 37.3% (16/43) and 46.4% (20/43) in the Salmonella-negative stalls respectively. Food-vendors kept water in buckets (reusing it all day), lacked toilet facilities, and prepared taco dressings the day before which remained at the tianguis without protection for 7.8 h on average. Consumption of street-vended food by local and tourist populations poses a health risk.

The Department of Health's "two week standard" for bowel cancer: is it working?

OBJECTIVE

To determine the effectiveness and efficiency of the Department of Health's new general practitioner referral guidelines for bowel cancer.

DESIGN

One year prospective audit.

SETTING

District general hospital serving a population of 550 000.

SUBJECTS

All patients with bowel cancer; all patients referred on the basis of the two week standard and to a routine colorectal surgical outpatient clinic.

MAIN OUTCOME MEASURES

Proportion of cancers referred on the basis of the two week standard and to other colorectal clinics; the proportion with the higher risk criteria and their diagnostic yields; stage of cancers diagnosed in outpatient clinics; and time to treatment.

RESULTS

A total of 249 cancers were diagnosed in the index year. Sixty five (26.1%) were referred to two week standard clinics, 40 (16.1%) to routine colorectal surgical outpatient clinics, 54 (22%) to other clinics, and 88 (35.3%) were emergencies. Thirteen patients per week were referred to the two week standard clinics and 85% (54/65) of cancers so referred were seen within two weeks. The diagnostic yield of cancer in the two week standard clinic was 9.4% (65/695) compared with 2.2% (40/1815) in the routine colorectal surgical outpatient clinic (p<0.0001). Eighty five per cent of patients with cancer referred to outpatients matched the guidelines for the two week standard clinics. Only 46% of this group were so referred. Overall, delay to treatment and Dukes' stage were not improved in patients diagnosed in the two week standard clinics.

CONCLUSIONS

Most patients with bowel cancer were not referred on the basis of the two week standard although most fulfilled the referral criteria, which had higher diagnostic yields. The two week standard clinics did not shorten the overall time to treatment or improve the stage of disease because the time lags before referral and after the outpatient appointment are the major causes of delay in the bowel cancer patient's journey.

Evidence of the effect of 'specialization' on the management, surgical outcome and survival from colorectal cancer in Wessex

BACKGROUND

A prospective audit of the management of colorectal cancer was established to investigate factors associated with variation in survival observed within the former Wessex region (population three million).

METHODS

Some 5173 patients (4562 surgically treated) with colorectal cancer diagnosed between 1991 and 1994 were followed for 5 years. Details of referral, diagnosis, surgical treatment, postoperative complications and outcomes were collected. The association between surgical outcomes and survival and both case volume and specialization (defined to include membership of the Association of Coloproctology of Great Britain and Ireland) was explored, accounting for variables with prognostic significance.

RESULTS

There was a statistically significant association between high-volume operators (more than 50 operations per year) and specialization. The greatest benefit was observed with respect to specialists versus non-specialists, in terms of a lower postoperative mortality rate (odds ratio 0.67 (95 per cent confidence interval (c.i. 0.53 to 0.84)), lower anastomotic leak rates (odds ratio 0.46 (c.i. 0.31 to 0.66)), higher local recurrence-free survival (hazard ratio 0.56 (0.44 to 0.71)) and better long-term survival (hazard ratio 0.76 (c.i. 0.71 to 0.83)).

CONCLUSION

There is a stronger association between surgical specialization in coloproctology and beneficial outcome than with high-volume caseloads. This is not entirely accounted for by case-mix or patient population, and is seen following colonic and rectal surgery and among patients with advanced disease.

Faecal contamination and enterotoxigenic Escherichia coli in street-vended chili sauces in Mexico and its public health relevance

The street-vended food industry provides employment and cheap ready-to-eat meals to a large proportion of the population in developing countries like Mexico, yet little is known about its role in the transmission of food borne diseases (FBD). Because of its wide consumption, street-vended chili sauces in Mexico are potential vehicles of FBD. An observational study was performed in Mexico City collecting 43 street-vended chili sauces. These sauces were prepared under poor hygienic conditions of handling and selling. Consumers add 4-8 ml of chili sauce per taco, ingest 2-5 tacos per meal and on average, 50 consumers frequent a stall per day. Seventeen (40%) samples were faecally contaminated and 2(5%) sauces harboured sufficient enterotoxigenic Escherichia coli to cause disease. Weestimate that the consumption of only one of these chili sauces could result in ETEC disease inat least 21,000 consumers per year, making them important potential vehicles of FBD.

Structural and functional features of modified heat-stable toxins produced by enteropathogenic Klebsiella cells

Heat-stable enterotoxins (STs) are 18- or 19-amino acid peptides (STa or ST1) produced by enteropathogenic bacteria with small differences in their amino acid sequence and a highly conserved carboxy terminus. All STs contain a core of three disulfide bridges whose integrity is believed to be necessary for full biologic activity. We previously reported that strains of Klebsiella pneumoniae transformed by the plasmid pSLM004 produce a modified toxin not recognized by MAb raised against genuine Escherichia coli ST. Investigation of the chemical structure of the modified toxins revealed that three new toxins were present. These were purified to homogeneity by a series of sequential chromatography on reverse-phase columns using guanylate cyclase to monitor the enterotoxic activity during purification procedures. The sequence of the modified toxins was obtained by a combination of Edman degradation and mass spectrometry, showing that they are proteolytically processed forms of E. coli ST1b. In particular, toxin A-2 lacks the cysteine at position 18 and then is not able to form the disulfide bridge cysteine-10-cysteine-18. All three toxins showed the ability to stimulate guanylate cyclase and to elicit chloride secretion in Caco-2 cell monolayers mounted in Ussing chambers. Toxin A-1 and toxin B demonstrated greatly reduced immunoreactivity whereas toxin A-2 was not recognized at all in the ELISA. It is likely that the three modified toxins were generated by Klebsiella specific proteolytic processing of the original pretoxin. These results have important implications for the diagnosis and prevention of heat-stable toxin-induced diarrhea.

Bascom's operation in the day-surgical management of symptomatic pilonidal sinus

BACKGROUND

Many treatments for symptomatic pilonidal sinus disease have been described. Ambulatory treatment with minimal morbidity and a rapid return to normal activity is desirable. Bascom's operation fulfils these requirements. This paper describes the operative technique and results of treatment.

METHODS

Some 218 patients of mean age 27 years were treated as day cases. The mean duration of symptoms was 2.4 years. Sixty-eight per cent of patients had complex disease with more than two midline pits and/or a lateral discharging sinus. One hundred and eighty-three patients (84 per cent) were operated on under local anaesthesia.

RESULTS

Ninety-five per cent of patients have been followed up for a mean of 12.1 (range 1-60) months. All except one midline wound healed. Lateral wounds healed after a mean of 4.0 (range 1-15) weeks. Postoperative complications were few, including bleeding in 4 per cent and abscess formation treated by reopening the lateral incision in 6 per cent. Twenty-one patients (10 per cent) have had recurrence and have needed reoperation.

CONCLUSION

Bascom's operation is simple and results in considerable financial savings with minimal social disruption and an early return to work. Recurrent disease is no more frequent than after other treatments.

Evaluation of Delorme's procedure as a treatment for full-thickness rectal prolapse

BACKGROUND

Delorme's procedure is a well tolerated perineal operation for full-thickness rectal prolapse. However, prolapse recurrence is common and reported recurrence rates vary widely. This study attempted to standardize outcome assessment for recurrence following primary and subsequent Delorme's operations. Patient and operative factors were analysed to identify any that might improve patient selection.

METHODS

Some 101 primary and 17 secondary Delorme's procedures were carried out on 113 consecutive patients presenting with rectal prolapse, who were followed for a minimum of 12 months, unless death or recurrent prolapse intervened. The rate of prolapse recurrence was calculated using the Kaplan-Meier method of analysis. Patient age, sex, grade of incontinence, presence of diverticular disease, length of mucosal resection and position in the operative series were analysed to identify factors affecting recurrence.

RESULTS

The predicted recurrence-free period for 50 per cent of patients undergoing primary and secondary Delorme's procedures was 91 (95 per cent confidence interval 77-105) and 27 (15-39) months respectively. None of the patient or operative factors analysed was related to recurrent prolapse.

CONCLUSION

Delorme's procedure is a simple operation with satisfactory functional results which can be considered in all patients of all ages. However, high recurrence rates for primary and repeat operations should be explained to patients when planning their surgical management.

Increased-contrast, high-spatial-resolution, diffusion-weighted, spin-echo, echo-planar imaging

An insertable head gradient coil with a maximum gradient amplitude of 45 mT/m and a rise time of 150 musec along all three major axes was used to collect high-spatial-resolution, single-shot, spin-echo, echo-planar, diffusion-weighted magnetic resonance images with b values ranging from 0 to 2,200 sec/mm2. Improvements in spatial resolution allowed better visualization of large white matter tracts and their relation to adjacent anatomic structures. Excellent contrast and anatomic detail were revealed for most structures in the brain when a sufficient number of acquisitions were collected.

Theory and application of static field inhomogeneity effects in gradient-echo imaging

The influence of local static magnetic field inhomogeneities on gradient-echo imaging is discussed and the underlying theoretical aspects are reviewed. A high-resolution approach is suggested to suppress image distortion and restore signal loss due to spin dephasing. Acquisition of three-dimensional data sets not only overcomes part of the limitations associated with gradient echoes but also makes it possible to extract local information about the strength or direction of background gradients and relative susceptibility changes between different tissues. Applications of the suggested approach in the human brain for anatomical imaging as well as for extraction of physical and physiological parameters are presented and discussed.

Physiological changes after Delorme's procedure for full-thickness rectal prolapse

Anal sphincter pressures, rectal compliance and sensation in 19 women of mean age 77 (range 57-94) years were studied before and after Delorme's procedure for full-thickness rectal prolapse. No patient had significant problems with defaecation after operation. There were no significant changes in anal sphincter pressures but the volume of first rectal sensation decreased from a median of 140 ml before surgery to 65 ml after the procedure (P = 0.01) and the maximum tolerated rectal volume declined from a median of 249 ml to 120 ml (P = 0.001). Rectal compliance was reduced from a median of 142.9 ml/kPa to 12.2 ml/kPa (P = 0.002). Improved rectal sensation and lowered compliance are associated with a reduced incidence of defaecatory problems after Delorme's procedure.

Receptors for Escherichia coli heat stable enterotoxin in human intestine and in a human intestinal cell line (Caco-2)

Escherichia coli heat stable enterotoxin (STa) and the newly identified endogenous ligand guanylin bind to an intestinal receptor and activate membrane bound guanylate cyclase. We compared STa binding and affinity crosslinking of STa receptors in human small intestine to those in the Caco-2 human colon carcinoma cell line. STa had similar kinetics of binding in human intestinal and Caco-2 brush border membranes. In both human intestine and Caco-2 brush border membranes, multiple specifically radiolabeled bands, including a 140-165 kDa band, were identified by affinity crosslinking. However, in human intestine the most prominent autoradiographic species was a 60 kDa band. A 60 kDa protein was also specifically immunoprecipitated from solubilized human brush border membranes using antisera raised against a cloned STa receptor fusion protein. Our observations of multiple crosslinked proteins in human intestine and Caco-2 cells could be explained by the existence of several members of a family of STa receptors and/or the existence of smaller STa binding proteins generated by the protease cleavage of a larger complete STa receptor.

The alpha 2-macroglobulin receptor/low density lipoprotein receptor-related protein binds and internalizes Pseudomonas exotoxin A

The alpha 2-macroglobulin receptor/low density lipoprotein receptor-related protein (alpha 2 MR/LRP) is a large cell-surface glycoprotein consisting of a 515-kDa and an 85-kDa polypeptide; this receptor is thought to be responsible for the binding and endocytosis of activated alpha 2-macroglobulin and apoE-enriched beta-very low density lipoprotein. A similar high molecular weight glycoprotein has been identified as a potential receptor for Pseudomonas exotoxin A (PE). We demonstrate that the alpha 2 MR/LRP and the PE-binding glycoprotein have a similar mobility upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis and are immunologically indistinguishable. Furthermore, affinity-purified alpha 2 MR/LRP binds specifically to PE but not to a mutant toxin defective in its ability to bind cells. The 39-kDa receptor-associated protein, which blocks binding of ligands to alpha 2 MR/LRP, also prevents binding and subsequent toxicity of PE for mouse fibroblasts. The concentration of receptor-associated protein that was required to reduce binding and toxicity to 50% was approximately 14 nM, a value virtually identical to the KD measured for the interaction of receptor-associated protein with the purified receptor. Overall, the studies strongly suggest that the alpha 2 MR/LRP is responsible for internalizing PE.

Implantation metastasis from adenocarcinoma of sigmoid colon into fistula in ano

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Mouse liver contains a Pseudomonas aeruginosa exotoxin A-binding protein

The opportunistic pathogen Pseudomonas aeruginosa produces several potential virulence factors, including the ADP-ribosylating toxin, exotoxin A (PE). Studies using a burned mouse model have shown that PE consistently inhibits protein synthesis and depletes elongation factor 2 in mouse liver and variably in other organs. One reason for toxin sensitivity could be the presence of a PE receptor on the surface of cells. Therefore we examined detergent extracts of mouse tissues for the presence of toxin-binding proteins. Proteins which specifically bind PE were present in extracts from liver, kidney, lung, spleen, and heart. Because liver appears to be a prominent target for the toxin in a burned animal, we choose to isolate the PE-binding protein from mouse liver and compare this protein to the recently characterized toxin-binding protein from toxin-sensitive mouse LM fibroblasts. The toxin-binding proteins from both sources have a molecular mass of approximately 350 kDa, share similar protease digestion profiles, and are glycosylated. However the glycosylation patterns for the two species are quite different. Both glycoproteins bind toxin with high avidity. The toxin-binding moiety is located, at least in part, on the plasma membrane and thus could represent the receptor involved in internalization of toxin molecules responsible for cell death.

Isolation and characterization of Pseudomonas aeruginosa exotoxin A binding glycoprotein from mouse LM cells

A Pseudomonas aeruginosa exotoxin A (PE) binding glycoprotein was affinity purified from toxin sensitive mouse LM cells. The binding protein was solubilized with Triton X-100 or Nonidet P-40 and purified on a PE-Sepharose affinity column. Polyacrylamide gel electrophoresis yielded a single band with an estimated molecular mass of greater than 300,000 Da. N-Linked carbohydrate was present, accounting for approximately 10% of the total mass of the molecule. The purified protein specifically bound PE. Incubation of purified protein specifically bound PE. Incubation of purified PE binding protein with toxin reduced toxicity to LM cells. We speculate on the role of this toxin binding glycoprotein in the intoxication process.