Structure-function analysis of PorXFj, the PorX homolog from Flavobacterium johnsioniae, suggests a role of the CheY-like domain in type IX secretion motor activity

The type IX secretion system (T9SS) is a large multi-protein transenvelope complex distributed into the Bacteroidetes phylum and responsible for the secretion of proteins involved in pathogenesis, carbohydrate utilization or gliding motility. In Porphyromonas gingivalis, the two-component system PorY sensor and response regulator PorX participate to T9SS gene regulation. Here, we present the crystal structure of PorXFj, the Flavobacterium johnsoniae PorX homolog. As for PorX, the PorXFj structure is comprised of a CheY-like N-terminal domain and an alkaline phosphatase-like C-terminal domain separated by a three-helix bundle central domain. While not activated and monomeric in solution, PorXFj crystallized as a dimer identical to active PorX. The CheY-like domain of PorXFj is in an active-like conformation, and PorXFj possesses phosphodiesterase activity, in agreement with the observation that the active site of its phosphatase-like domain is highly conserved with PorX.

Effect of the first wave of COVID-19 on Poison Control Centre activities in 21 European countries: an EAPCCT initiative

BACKGROUND

Public health emergencies often affect Poison Control Centre (PCC) operations. We examined possible effects of the coronavirus disease 2019 (COVID-19) pandemic on call volume, call characteristics, and workload in European PCCs.

METHOD

All 65 individual European PCCs were requested to supply data on the number of calls and call characteristics (caller, age groups, reason and specific exposures) from March to June in 2018, 2019, and 2020 (Part 1). Number of calls with specific characteristics was normalised to all calls. Calls (N) and call characteristics (%) were compared between 2020 and 2018/2019 (average), within PCCs/countries and grouped. Correlation between call volume and COVID-19 cases per PCC/country was examined. All PCCs received a survey on workload (Part 2). Parts 1 and 2 were independent.

RESULTS

For Part 1, 36 PCCs (21 countries) supplied 26 datasheets. PCCs in the UK and in France merged data and supplied one datasheet each with national data. Summed data showed an increase of 4.5% in call volume from 228.794 in 2018/2019 (average) to 239.170 in 2020 (p < 0.001). Within PCCs/countries, calls significantly increased for 54% of PCCs/countries (N = 14/26) and decreased for 19% (N = 5/26), three of which (N = 3/5) only serve medical professionals. Correlation between call volume and COVID-19 cases was (non-significant) positive (Rho >0.7) in 5/26 PCCs/countries (19%), and negative in 6/26 (23%). Call characteristics (median proportion of grouped data in 2018/2019 vs. 2020) changed: fewer medical professionals called (40 vs. 34%, p < 0.001), calls on intentional exposures decreased (20 vs. 17%, p < 0.012), as did calls on patients between 13 and 17 years (5 vs. 4%, p < 0.05). Calls on specific exposures increased; disinfectants from 1.9 to 5.2%, and cleaning products from 4.4 to 5.7% (p < 0.001). For Part 2, 38 PCCs (24 countries) filled the survey on workload (number/length of shifts and time on PCC duties), which increased in 23/38 PCCs (61%), while 10/38 (26%) worked with fewer employees.

CONCLUSIONS

Obtaining aggregated European PCC data proved challenging but showed an increase in overall call volume and workload during the first COVID-19 wave. Call characteristics changed including fewer calls from professionals and more calls on specific exposures. Within single PCCs/countries a variety of effects was observed.

A novel treatment for supraglottic stenosis secondary to immunoglobulin G4-related disease

Although immunoglobulin G4-related disease (IgG4-RD) has a predilection for the head and neck region, laryngeal pathology is rare. We report a case of supraglottic stenosis due to IgG4-RD together with a novel treatment strategy of employing a laryngeal stent. A 69-year-old man was referred with longstanding dyspnoea and worsening inspiratory stridor. Despite two supraglottic dilations over a 12-month period, his stenosis recurred and symptoms persisted. Serum investigations revealed elevated IgG4 levels (2.390g/l), with IgG4 infiltrate in laryngeal biopsies. The patient underwent endoscopic balloon dilation, intralesional Depo-Medrone® injection, CO₂ laser therapy and insertion of a laryngeal stent to prevent re-stenosis. Rituximab and prednisolone were commenced postoperatively and the stent was removed at 6weeks. No stenosis recurrence was visualised over a further 12-month follow-up period. Sixteen cases of laryngeal lesions with confirmed IgG4 infiltrate in biopsies have been reported in the worldwide literature to date. Based on a literature review and our experience, we recommend that similar laryngeal pathologies undergo early IgG4 serological testing and biopsy immunohistochemistry. Prompt diagnostic confirmation may prevent unnecessary surgical interventions and optimise immunosuppression. Furthermore, the use of a laryngeal stent following laryngeal surgery may help reduce stenotic recurrence and promote healing.

538 Patient Satisfaction from ENT Phone Consultations During COVID-19

Introduction

Telephone consultations (TCs) have rapidly increased in the outpatient setting due to the coronavirus pandemic. We have implemented a quality improvement project to improve patient satisfaction of TCs in our unit.

Method

This was a prospective complete-cycle project, with online patient satisfaction questionnaires sent following TCs in ENT clinics. This consisted of 28 questions including the Medical Interview Satisfaction Scale (MISS-21).

Based on results and a current literature review, a two-pronged intervention was designed, comprising of staff education and application of a model structured TC framework. A follow-up survey was subsequently undertaken.

Results

100 patient questionnaires were collected (April & June 2020). Significant improvements in MISS-21 scores were seen over the two surveys (p = 0.026). An average MISS-21 score of 114.6 (range 49 – 147) was seen in the first survey, with a mean score of 128.5 (range 79 – 142) seen in the second (maximum score of 147). There was a significantly increased preference for TC over FTF appointments over the two surveys (p = 0.021).

Conclusions

We have shown significant improvements in patient satisfaction and an increased TC preference through use of a structured consultation model. Its potential benefits in infection control and impact on outpatient workload may see TCs persist in the post-coronavirus era.

544 Vasculitic Subglottic Stenosis: A Question of Immunosuppression?

Introduction

Subglottic stenosis (SGS) is the commonest manifestation of tracheobronchial disease in granulomatosis with polyangiitis (GPA) and carries a high degree of morbidity.

Management of SGS-GPA is a double-edged sword. Delayed treatment may cause respiratory compromise and infectious complications. However, aggressive surgical management may initiate a systemic inflammatory response, reactivating the vasculitic cascade and potentially lead to long-term complications including renal vasculitis and consequential end-stage renal failure.

There is currently no internationally agreed management strategy for this disease.

Method

This retrospective review was undertaken to analyse our unique combination of surgical dilatations and immunosuppressive-focused adjuvant management strategy between years 2011-2020.

Results

Sixteen of our one hundred and nine GPA patients (14.7%) had SGS and were included in our analysis. Whilst three patients (18.8%) improved solely on medical treatment, thirteen (81.3%) required combined surgery and immunosuppression (consisting of cyclophosphamide or Rituximab regimens). Thirty-nine surgical dilatations and two tracheostomies were performed over a mean 53-month follow-up period, with a calculated mean procedure rate of one every 24.8 months (2.7 - 89 months).

Conclusions

Our current management strategy affords a lower procedure rate at every 24.8 months compared to other published studies with combined procedure rate at every 14.9 months.

Patient satisfaction from ENT telephone consultations during the coronavirus disease 2019 pandemic

BACKGROUND

Telephone consultations have rapidly increased in the out-patient setting because of the coronavirus pandemic. A quality improvement project was implemented to improve patient satisfaction of telephone consultations in our unit.

METHODS

This was a prospective complete-cycle project. Patient satisfaction questionnaires were sent to patients following telephone consultations in ENT clinics. Based on a literature review and initial results, clinicians were encouraged to follow a structured consultation format. A second questionnaire survey was conducted following its implementation.

RESULTS

One hundred patient questionnaires were collected during the survey (April and June 2020). There was significant improvement over the two surveys in terms of satisfaction scores (p = 0.026), along with a significantly increased preference for telephone consultations over face-to-face consultations (p = 0.021).

CONCLUSION

This study showed significant improvement in patient satisfaction and an increased telephone consultation preference through the use of a structured consultation model. The potential benefits in terms of infection control and impact on out-patient workload may see telephone consultations persist in the post-coronavirus era.

Relationship of amyloid beta and neurofibrillary tau deposition in Neurodegeneration in Aging Down Syndrome (NiAD) study at baseline

IMPORTANCE

Adults with Down syndrome (DS) are at high-risk of revealing Alzheimer's disease (AD) pathology, in part due to the triplication of chromosome 21 encoding the amyloid precursor protein. Adults with DS are uniformly affected by AD pathology by their 30's and have a 70% to 80% chance of clinical dementia by their 60's. Our previous studies have assessed longitudinal changes in amyloid beta (Aβ) accumulation in DS.

OBJECTIVE

The goal of the present study was to assess the presence of brain tau using [18F]AV-1451 positron emission tomography (PET) in DS and to assess the relationship of brain tau pathology to Aβ using Pittsburgh Compound B (PiB)-PET.

DESIGN

Cohort study.

SETTING

Multi-center study.

PARTICIPANTS

Participants consisted of a sample of individuals with DS and sibling controls recruited from the community; exclusion criteria included contraindications for magnetic resonance imaging (MRI) and/or a medical or psychiatric condition that impaired cognitive functioning.

EXPOSURES

PET brain scans to assess Aβ ([11C]PiB) and tau ([18F]AV-1451) burden.

MAIN OUTCOMES AND MEASURES

Multiple linear regression models (adjusted for chronological age, sex and performance site) were used to examine associations between regional [18F]AV-1451 standard uptake value ratio (SUVR) (based on regions associated with Braak stages 1-6) and global [11C]PiB SUVR (as both a continuous and dichotomous variable).

RESULTS

A cohort of 156 participants (mean age = 39.05, SD(8.4)) were examined. These results revealed a significant relationship between in vivo Aβ and tau pathology in DS. As a dichotomous variable, [18F]AV-1451 retention was higher in each Braak region in PiB(+) participants. We also found, based on our statistical models, starting with the Braak 3 region of interest (ROI), an acceleration of [18F]AV-1451 SUVR deposition with [11C]PiB SUVR increases.

A rise in facial nerve palsies during the coronavirus disease 2019 pandemic

OBJECTIVE

An increase in spontaneous lower motor neuron facial nerve (VIIth cranial nerve) palsies was seen during the severe acute respiratory syndrome coronavirus 2 outbreak in our emergency clinic. This led us to perform a single-centre cohort review.

METHODS

A retrospective review was conducted of VIIth cranial nerve palsies from January to June 2020 and the findings were compared to those cases reviewed in the previous year. The severe acute respiratory syndrome coronavirus 2 incidence of the cohort was compared with that of the Liverpool population.

RESULTS

Our VIIth cranial nerve palsy incidence in the 2020 period was 3.5 per cent (30 out of 852), 2.7 higher than last year's rate of 1.3 per cent (14 out of 1081), which was a statistically significant difference (p < 0.01). Two of the 17 patients in our cohort tested positive for severe acute respiratory syndrome coronavirus 2 (11.8 per cent), contrasting with Liverpool's severe acute respiratory syndrome coronavirus 2 incidence (0.5 per cent).

CONCLUSION

Severe acute respiratory syndrome coronavirus 2 may be responsible for an increased number of facial nerve palsies; it is important for clinicians to be aware that this may being an initial presentation of the disease.

A prospective audit of early stoma complications in colorectal cancer treatment throughout the Greater Manchester and Cheshire colorectal cancer network

AIM

The study aimed to identify the incidence of early stoma problems after surgery for colorectal cancer to identify predisposing factors and to assess the effect on discharge from hospital and the greater need for community stoma care.

METHOD

A prospective study of 192 patients was carried out over a six-month period in the 13 units of the Greater Manchester and Cheshire Cancer Network. Stoma problems were categorized into fistula, leakage, pancaking, necrosis, retraction, separation, stenosis, skin problems, parastomal hernia, suboptimal stoma site and need for resiting or refashioning. Differences in incidence between units (anonymized) were analysed, and the effect of stoma complications on length of hospital stay and the need for additional community stoma care was determined.

RESULTS

One hundred and ninety-two patients with stomas were included, of which 52 (27.1%) were identified as being problematic (range 0-66.7% between units). Significant risk factors included stoma type (colostomy) (P < 0.05), short stoma length (P = 0.006), higher BMI (P = 0.043), emergency surgery (P = 0.002) and lack of preoperative site marking (P < 0.001). Problematic stomas were associated with longer hospital stay (P < 0.001) and increased community care (P < 0.001).

CONCLUSION

Stoma type, stoma length, body mass index, emergency surgery and lack of preoperative marking were significant risk factors. Overall complication rates compare favourably with other studies.

Intussusception of the appendix secondary to mucinous cystadenoma: A rare cause of abdominal pain

A 35-year-old woman was seen as an outpatient with a 3-month history of pain in the right iliac fossa. A CT scan of her abdomen revealed the presence of a mucocele of the appendix. Intra-operatively, an appendico-appendicular intussusception was found. Histology confirmed the presence of a mucinous cystadenoma with the presence of acellular mucin on the serosal surface of the appendix. This association has rarely been described in the literature. Prompt surgical intervention is advocated to prevent the subsequent development of pseudomyxoma peritonei. We present a case of intussusception of the appendix with a mucinous cystadenoma as its lead point.

The pharmacokinetics and safety of porfimer after repeated administration 30-45 days apart to patients undergoing photodynamic therapy

BACKGROUND

Porfimer is an intravenous (i.v.) injectable photosensitizing agent used in the photodynamic treatment of tumours and of high-grade dysplasia in Barrett's oesophagus.

AIM

To assess the pharmacokinetics as well as the safety profiles of porfimer after a first and a second dose administered 30-45 days apart in patients undergoing photodynamic therapy.

METHODS

Nineteen patients (16 with cholangiocarcinoma) were enrolled. Porfimer sodium was administered by i.v. injection over 3-5 min. Blood samples were collected prior to starting i.v. drug injection and postdose at different time points after the first and second administrations.

RESULTS

Porfimer exposure values after the second administration were statistically higher than those observed after the first administration, suggesting a slight accumulation of porfimer following repeated administration. The apparent mean elimination half-life of porfimer increased from 410 h after the first administration to 725 h after the second administration. The safety profiles of porfimer after a first and a second administration were similar and did not raise additional concern. Eight patients experienced nine serious adverse events. Only photosensitivity was deemed study-drug related.

CONCLUSION

Porfimer appears to display a safe and tolerable profile when used in patients requiring a second photodynamic therapy within 45 days.

A technically difficult endorectal ultrasound is more likely to be inaccurate

OBJECTIVE

Endorectal ultrasound (ERUS) is well established as an accurate modality for local staging of rectal tumours. The aim of this study was to identify reasons for inaccurate staging of tumours, and to assess whether difficulties encountered during scanning are likely to influence accuracy.

PATIENTS AND METHODS

ERUS was performed by a single operator using a 10 MHz rigid instrument. One hundred and seventeen patients that had both ERUS and surgery are included in this study (patients that had pre-operative radiotherapy were excluded). During ERUS, procedural conditions and limiting factors were recorded. Data was collected prospectively.

RESULTS

In 78 (66.7%) patients no technical difficulty was encountered during ERUS. In this group accuracy was 80% for T-stage and 77% for N-stage. Specific reasons for inaccuracy identified in this group were: inflammatory lymph nodes (from a tumour associated abscess and a colovesical fistula) and deep biopsy causing a submucosal defect with intramural haemorrhage in benign lesions (2 cases). In the remaining 39 (33.3%), the following problems were encountered: stenotic lesions (23), patient discomfort (8), poor bowel preparation (6), and scarring from previous surgery (2). In 11 patients from this group, the scan was considered inconclusive and no stage could be determined. For the other 28, the accuracy for T-stage was 68% and for N-stage 67%.

CONCLUSION

A technically difficult ERUS is likely to give an inconclusive or inaccurate result for both T-stage (P = 0.001) and N-stage (P = 0.003). In this situation a repeat scan may be considered (where appropriate). Alternatively, further assessment by MRI or flexible endoscopic ultrasound may be considered.

Local resection of rectal tumours using the Salvati operating proctoscope--a safe and effective technique

BACKGROUND

Per-anal excision can be an effective method for treating large rectal adenomas and selected rectal cancers. This procedure is suitable for adenomas that are too large for colonoscopic excision and for early rectal cancers in patients that are unfit for major resection.

PATIENTS AND METHODS

We retrospectively reviewed 37 patients (16 male, 21 female) that had a local resection using a Salvati operating proctoscope. Fifteen had rectal cancer and 22 had rectal adenoma and all have been followed-up for a median of 14 months (range 2-65). Most cancers were staged pre-operatively with endorectal ultrasound and 6 cancer patients received adjuvant therapy.

RESULTS

There were no intra-operative complications, 6 minor postoperative complications, none requiring re-intervention (1 peri-anal haematoma, 2 postoperative anaemia, 2 chest complications, 1 secondary haemorrhage) and no peri-operative deaths. Lesions were histologically completely excised in 33 (89%). Thirty-four (92%) did not have any recurrence, 2 (5%) adenomas recurred (both successfully treated with further local resection) and 1 (3%) failed to attend for follow-up. Six have since died, all from comorbid conditions.

CONCLUSION

Local resection of rectal tumours using the operating proctoscope is a low cost technique with a low complication rate. Outcome of this treatment is good, and similar to other surgical modalities. Local tumour recurrences are uncommon and can be successfully treated with further local treatment.

Steady-state measurement of NO and CO lung diffusing capacity on moderate exercise in men

Using a rapidly responding nitric oxide (NO) analyzer, we measured the steady-state NO diffusing capacity (DL(NO)) from end-tidal NO. The diffusing capacity of the alveolar capillary membrane and pulmonary capillary blood volume were calculated from the steady-state diffusing capacity for CO (measured simultaneously) and the specific transfer conductance of blood per milliliter for NO and for CO. Nine men were studied bicycling at an average O(2) consumption of 1.3 +/- 0.2 l/min (mean +/- SD). DL(NO) was 202.7 +/- 71.2 ml. min(-1). Torr(-1) and steady-state diffusing capacity for CO, calculated from end-tidal (assumed alveolar) CO(2), mixed expired CO(2), and mixed expired CO, was 46.9 +/- 12.8 ml. min(-1). Torr(-1). NO dead space = (VT x FE(NO) - VT x FA(NO))/(FI(NO) - FA(NO)) = 209 +/- 88 ml, where VT is tidal volume and FE(NO), FI(NO), and FA(NO) are mixed exhaled, inhaled, and alveolar NO concentrations, respectively. We used the Bohr equation to estimate CO(2) dead space from mixed exhaled and end-tidal (assumed alveolar) CO(2) = 430 +/- 136 ml. Predicted anatomic dead space = 199 +/- 22 ml. Membrane diffusing capacity was 333 and 166 ml. min(-1). Torr(-1) for NO and CO, respectively, and pulmonary capillary blood volume was 140 ml. Inhalation of repeated breaths of NO over 80 s did not alter DL(NO) at the concentrations used.

Use of arm veins for lower extremity arterial bypass--results, anatomical features and technical considerations

Forty lower limb bypasses using arm veins were performed on 37 patients. The indications for surgery were limb threat in 50% of cases, graft failure in 33%, aneurysms in 10% and claudication in 7%. Saphenous veins were absent because of prior use in 73% of cases, and because they were unsuitable in 27%. A single vein was used in 48%, 2 veins in 40% and 3 veins in 12% of cases. Seventy-four per cent of cases had a single-vessel run-off below the distal anastomosis. Eighty-two per cent of the distal anastomoses were to infrapopliteal arteries. The primary and secondary rates of these 40 bypasses at a mean follow-up of 14 months (range 1-40 months) were 74% and 90%, respectively. Limb salvage was 94%. Peri-operative morbidity and mortality were 23% and 3%, respectively. The anatomical and technical aspects of harvesting arm veins are critical to the success of this procedure and will be emphasised. We have found arm veins to be a durable source of accessible autogenous grafts for lower limb revascularisation in the absence of suitable saphenous veins.

A clinical comparison of Dacron patch closure of small-caliber carotids compared with primary closure of large-caliber carotids after endarterectomy

The objective was to study results of carotid endarterectomies performed between 1975 and 1991, comparing primary closure to Dacron patch closure. This was a retrospective study. Data from patient follow-up by physical examination, chart review, and Duplex study were used. Scan data were obtained in 92 of the primary cases, at a mean of 5 years postoperatively, and in 63 of the patch cases, at a mean of 4.1 years postoperatively. During this period, 269 endarterectomies were closed primarily and 101 were closed with a knitted Dacron patch. Twenty patients in the primary group and nine patients with patch closure were lost to follow-up, which extended for up to 12.5 years, with a mean of 4.7 +/- 3.6 years. No acute closures, infections or aneurysms developed in either group. Perioperative stroke incidence was 4.1 per cent for primary closure and 3.0 per cent for the patch group (P > 0.05). Late stenosis occurred in 17.3 per cent of the primary group and 11.1 per cent of the patch closure group (P > 0.05). Five-year survival was 76.2 per cent in the primary group, compared with 79.2 per cent for patch closure. Late stroke incidence was 2.8 per cent in the primary group and 3.3 per cent in the patch closure group. Results of smaller (< or = 3.5 mm) carotid arteries closed with knitted Dacron patches are equivalent to those of larger carotid arteries closed primarily.

Transcranial Doppler intraoperative monitoring during carotid endarterectomy: experience with regional or general anesthesia, with and without shunting

To determine whether continuous transcranial Doppler (TCD) can significantly alter therapeutic conduct during carotid endarterectomy, a retrospective study of 117 carotid endarterectomies was done. There was no perioperative mortality; one perioperative stroke was recorded in a patient who was symptomatic preoperatively. Continuous TCD of the ipsilateral middle cerebral artery (MCA) was attempted in 99 cases, and successful in 90; nine patients (9.1%) had inadequate temporal windows for MCA access. MCA velocities and emboli were recorded before and during carotid cross-clamping, and on clamp release. There were no significant velocity differences between the patients with regional and general anesthesia, and patients with and without carotid shunts, but there was a statistically significant difference in the total number of emboli (air and particulate transients) noted for the shunted and nonshunted patients after clamp release: 12.7 versus 23.6, respectively (p = 0.05). There was no significant difference when particulate and air microemboli were compared. During surgery TCD identified residual flow of less than 40% in the MCA in 17 patients (18.8%). TCD also identified hyperperfusion in two patients, shunt abnormalities in three patients, and influenced postop treatment in four patients, one of whom was returned to surgery. TCD is an important tool for identifying patients who would benefit from a shunt, preventing hyperperfusion, identifying postop emboli, and detecting technical errors.

Femoropopliteal bypass with externally supported knitted Dacron grafts: a follow-up of 200 grafts for one to twelve years

PURPOSE

This article reports our experience with externally supported, preclotted knitted Dacron grafts in femoropopliteal bypass.

METHODS

This is a retrospective analysis of a consecutive series of 154 patients who received 200 grafts (175 above knee and 25 below knee). Follow-up extended to 12 years (mean 59 1/2 months).

RESULTS

Primary patency rates for the entire series were 75%, 70%, and 47% at 3, 5, and 10 years, respectively. Above-knee grafts had 76%, 71%, and 50% rates and 3, 5, and 10 years, respectively. Below-knee grafts had 65% and 57% at 3 and 5 years, respectively. Limb-salvage rates were 87%, 79%, and 73% at 3, 5, and 10 years, respectively, for the 57 limbs operated on because of critical ischemia. The most significant predictor of graft failure was poor runoff as determined by preoperative arteriography. The effect of poor runoff was most pronounced in the first 3 months.

CONCLUSION

Externally supported, preclotted knitted Dacron grafts provide encouraging primary patency rates for above-knee femoropopliteal bypass. Poor leg vessel runoff is a major determinant of early graft failure.

Platelet aggregometry can accurately predict failure of externally supported knitted Dacron femoropopliteal bypass grafts

PURPOSE

Our purpose was to evaluate whether a method for quantification of platelet aggregability will predict failure of knitted Dacron femoropopliteal bypass grafts.

METHODS

A numerically derived platelet aggregation (PA) score, based on the aggregation pattern and platelet count, was determined in the 40 patients available for platelet analysis who underwent 53 femoropopliteal bypass grafts with preclotted, 6 mm, externally supported knitted Dacron grafts from 1981 to 1991 (mean follow-up 50 months). The preoperative score was found to remain stable after surgery, enabling the use of postoperative values when preoperative values were not available. The PA score was available in 19 patients (23 grafts) before surgery and 23 patients (30 grafts) after surgery. The following factors were analyzed for predicting graft failure by the Cox proportional hazards regression model: PA score, age, gender, history of smoking, coronary artery disease, hypertension, hyperlipidemia, cerebrovascular disease, diabetes, claudication versus limb salvage, site of the distal anastomosis, previous ipsilateral bypass, and state of the runoff as determined by preoperative angiography.

RESULTS

Of the studied risk factors, the value of the PA score was the most significant predictor of graft closure (p < 0.0001). An increase of 10 units was associated with an increased relative risk of 2.02. Throughout the follow-up period, 15 of 16 grafts remained patent in patients with a PA score of 15 or less, but only 2 grafts out of 17 remained patent in patients with a PA score of 30 or greater.

CONCLUSIONS

These data suggest that the PA score is a potential risk factor for failure of femoropopliteal bypass with externally supported knitted Dacron grafts.

Axillofemoral bypass with externally supported, knitted Dacron grafts: a follow-up through twelve years

PURPOSE

The purpose of this study was to review our experience with externally supported, knitted Dacron grafts used for axillofemoral bypass.

METHODS

Retrospective analysis was performed on records of 79 consecutive axillofemoral bypass graft operations performed on 77 patients from January 1978 to April 1990.

RESULTS

The mortality rate within 30 days of operation was 5% (four of 79); 36 patients died in the follow-up period; none died of graft causes. During this 12-year period (mean follow-up 42 months) three patients were unavailable for follow-up. The primary patency rate was 78% at 5 years and 73% at 7 years, with no change thereafter. Neither the graft configuration (i.e., axillounifemoral [n = 50] vs axillobifemoral [n = 29]) nor patency of the superficial femoral artery had an impact on the primary patency rate. Patients who underwent surgery for disabling claudication (n = 30 grafts) had a primary patency rate of 80% at 6 years compared with 65% at 6 years for those who required surgery for limb salvage (n = 49 grafts); the difference was not significant (p = 0.37). Actuarial survival of patients with axillofemoral grafts was 23% at 10 years compared with 72% in a concurrent population of patients with aortofemoral bypass (p < 0.001).

CONCLUSION

These findings indicate that axillofemoral bypass grafts may be appropriate for high-risk patients with severe aortoiliac disease who require revascularization for either limb salvage or incapacitating claudication.

Frustrations in delivering a dental service to the north coast of Labrador

The delivery of a dental service to 4,000 people by 2-3 dentists, appears straight forward, in theory. It proves to be a different story in reality. Having prior knowledge of these problems, may be of help to dentists who wish to work here. One must experience the situation for oneself, however. There are certainly a "more than normal" amount of problems to confront on a daily basis. Accommodation and travel arrangements, seem to be the most pressing issues which need improvement. The usual work span of a dentist is between one and three years. The amount of work done by each dentist can vary on a daily basis. Native traditions can be such that, patients do not show up at the dental clinic until too late. Violence, suicides, and alcohol or solvent and drug abuse, as is being seen today, can "burn out" any health worker. Equipment needs to be upgraded in some of the Stations, like Hopedale and Davis Inlet. Salaries need revising.

Carotid artery Dacron patch graft angioplasty: a ten-year experience

Of 394 carotid endarterectomies performed during a 10-year period, 36 (9%) included Dacron patch graft angioplasties. Patch graft angioplasties were used selectively in patients because they had undergone previous carotid endarterectomy or had small-caliber vessels. There were no postoperative infections, occlusions, emboli, stroke, or pseudoaneurysms. In addition, no clinically detectable recurrent stenoses developed in this high-risk group of patients. Twenty-four of the 27 patients available for follow-up were screened for asymptomatic stenoses with spectral analysis and B-mode imaging; there was no sign of hemodynamically significant recurrent stenosis in this group. These encouraging results support the continued selective use of Dacron patch graft angioplasty in carotid surgery.

Influence on healing in the canine thoracic aorta of three substances used to close the interstices of macroporous Dacron grafts

The influence on healing of three materials for closure of interstices in a macroporous Dacron arterial prosthesis were evaluated by 56-day implantation in the canine descending thoracic aorta. The materials studied were: the nondenatured fibrin deposited as a result of a 4-step preclot with autogeneic blood (n = 6), heat-coagulated autogeneic blood deposited by autoclaving the blood-soaked prosthesis (n = 6), and cross-linked human albumin (n = 6). Healing of autogeneic fibrin was superior with little difference between the other two materials.

A new combination therapy for selective and prolonged antiplatelet effect: results in the dog

This study characterizes the effect of dazmegrel, a thromboxane synthetase inhibitor, on platelet function in the dog and introduces its potential use in combination with aspirin therapy. Ex vivo testing of dazmegrel alone was performed with three dosages and three administration regimens. Platelet aggregation response, malondialdehyde formation and prostaglandin metabolites generation were evaluated. To maintain complete thromboxane A2 inhibition, dazmegrel had to be given 3 times per day at dosages of not less than 6 mg/kg. The same result was achieved with a single daily administration of combined dazmegrel and aspirin in equal dosages of 3 mg/kg. Dazmegrel, both alone and with aspirin, increased and sustained heightened levels of prostacyclin, unlike the simultaneous inhibition of both prostaglandin metabolites seen with aspirin therapy alone. Because the combination of dazmegrel and aspirin effectively blocks thromboxane A2 formation and also enhances prostacyclin formation, the synergistic action of these agents increases their combined antiplatelet effect to a level not attainable by either agent alone. The significance of this combined therapy warrants further experimental study and may soon merit clinical trial for the prevention of stroke and other major thrombotic complications.

The effect of predetermined thrombotic potential of the recipient on small-caliber graft performance

This study was designed to establish the influence of the recipient's thrombotic potential on the patency of small-caliber prostheses and to evaluate the subsequent improvement of graft performance by medicinally altering the prostaglandin balance in subjects predisposed to graft occlusion. Mongrel dogs were pretested and classified as low and high responders according to their thrombotic potential, measured as prostaglandin metabolite balance and platelet aggregability. High responders were randomly divided into two groups. Those assigned to serve as the medicated subjects were pretreated 1 week before surgery with a single oral daily administration of combined dazmegrel (UK-38,485) and aspirin in equal dosages of 3 mg/kg. Medication was continued throughout the experiment. Dacron grafts were implanted bilaterally in the carotid artery site in all subjects. Following a 3-week implantation period, the patency rate for the group with low thrombotic potential was 100%. In the animals with high thrombotic potential the patency rate was 10% for nonmedicated subjects and 100% for medicated subjects. These data support the concept that the thrombotic potential largely determines the capacity of the recipient's blood to thrombose small-caliber prostheses. Effective medicinal alteration of prostaglandin balance results in exceptionally increased patency of synthetic grafts.

A comparison of external velour and double velour Dacron grafts in the canine thoracic aorta

Six external velour (Bionit C. R. Bard, Inc.; Billerica, MA) and 11 double velour (Microvel Meadox Medicals, Inc.; Oakland, NJ) warp-knit Dacron grafts with lengths of 6 cm and diameters of 8 mm were implanted in the canine upper descending thoracic aorta for 56 days. Differences were observed: four of 11 double velour grafts developed major perigraft hematomas, while none of the external velour grafts exhibited this complication. Healing of the external velour grafts was virtually complete (average full wall healing and endothelial-like cell coverage of 97.0%, SD 5.9%) in contrast to the seven (of 11) double velour grafts that were free of perigraft hematoma (average full wall healing and endothelial-like cell coverage of 40.9%, SD 20.9%).

The influence of inner wall filamentousness on the performance of small- and large-caliber arterial grafts

Dacron prostheses with differing degrees of inner wall filamentousness were implanted in the canine descending thoracic aorta for 56 days (n = 14) and the carotid arteries for 21 days (n = 40). In the thoracic aorta the healed inner capsule of 8 mm internal velour grafts was approximately three times as thick as the inner capsule of external velour knitted prostheses. However, the early patency and rapidity of healing of these two types of prostheses were essentially the same. In the carotid arteries the patency of the 4 mm external velour prostheses was greater than that of the internal velour prostheses and the mean thrombus-free surface area of the external velour grafts was significantly greater than that of the internal velour grafts. These observations suggest that an internal velour surface is not deleterious to early patency in a large-caliber, high-flow artery but that it may be in a small-caliber, low-flow artery.

Aspirin therapy in small-caliber arterial prostheses: long-term experimental observations

To study the therapeutic effects of 3 mg/kg aspirin given at the time of surgery and postoperatively, Dacron carotid grafts with an internal diameter of 4 mm and a length of 6 cm were implanted bilaterally in mongrel dogs. Sixteen control grafts in eight subjects and 20 grafts in 10 subjects treated with aspirin were followed by serial angiograms until consecutive studies showed stable patency rates in both groups. Platelet aggregations, malondialdehyde production, serum salicylate levels, and thromboxane A2 and prostacyclin secretion (measured as thromboxane B2 and 6-keto-prostaglandin F1 alpha) were monitored prior to and throughout the experiment. Surface mapping, indium-111 uptake, factor VIII-related antigen staining, and scanning and transmission electron microscopy were performed on the grafts at sacrifice. This study demonstrates a protective effect on the early patency of small-caliber prostheses in the canine model with daily oral aspirin administration. The degree and duration of this effect depends on the preoperative baseline ratio of thromboxane to prostacyclin in each subject.

Total parenteral nutrition in renal transplantation. Experimental observations

The nutritional support of the transplant recipient as a means of improving the allograft response after transplantation has not been investigated. This experimental study was designed in an attempt to define the role of malnutrition and total parenteral nutrition (TPN) on the rejection of canine renal allografts. Twenty-three mongrel dogs (18-23 kg) received kidney transplants from unrelated donors. All animals were minimally immunosuppressed with azathioprine (5.0-2.5 mg/K/day). Daily serum creatinines, biweekly complete blood counts, serum protein, and total iron binding capacity (TIBC) were determined. Postmortem examination was performed on all animals. Four groups of animals were compared: Group I (n = 5) served as a control and was maintained postoperatively on a regular balanced diet (RBD). Group II (n = 6) and Group IV (n = 6) were gradually malnourished prior to operation by diet leading to 12 to 22 per cent loss of weight, decreased albumin (2.0-2.6 mg/dl) and decreased TIBC (greater than 30%). After transplantation, Group II was maintained on 50 per cent RBD, and in Group IV, TPN was started two days prior to transplantation. The rejection times were 6.2 +/- 1.2, 9.5 +/- 3.5, 12.0 +/- 3.9, and 9.1 +/- 4.1 (mean +/- SD) days, respectively, for Group I through IV. TPN was not detrimental or beneficial to the allograft response of canine kidneys. Malnutrition, however, delayed significantly (P less than 0.005) the appearance of rejection after transplantation. Our findings appear to suggest that TPN could be safely used prior to and after transplantation if indicated, since it does not significantly alter the dog allogenic response following transplantation.

Role of posttransplant kidney biopsy after hypothermic pulsatile perfusion

Biopsies were obtained from 24 perfused cadaver kidneys. The histologic findings were correlated with short- and long-term kidney function after transplantation. There was no correlation between structural findings present immediately after perfusion and transplantation and short- or long-term kidney function. Thus, we believe that one-hour posttransplant kidney biopsy does not have a role in assessing recently perfused and transplanted kidneys.

Important factors in islet cell transplantation: the role of pancreatic fragments' size, pH, potassium concentration and length of intraportal infusion

The role of pancreatic fragment size prior to collagenase treatment, pH, K+ concentration and length of intraportal infusion was studied in islet cell transplantation of streptozotocin-induced diabetic adult rats. This study demonstrates that pancreatic fragments of 1 mm prior to collagenase digestion, pH of 7.4, extracellular potassium concentration and 10 min of intraportal infusion are important factors in successful islet cell transplantation of adult rats receiving six donor pancreases for amelioration of chemical diabetes. These factors should be taken into consideration when consistent islet cell transplantation results are to be expected.

Cimetidine for kidney transplantation: experimental observations

H2-histamine receptor antagonists may augment delayed hypersensitivity. The effect of cimetidine, a H2-histamine receptor antagonist, was assessed in renal allografts in dogs. The animals in the control group (I) (n = 5) received a renal transplant and moderate immunosuppression with azathioprine and prednisone. The dogs in the experimental group (II) (n = 8) were given cimetidine in two doses (300/150 mg, twice daily). Group III (n = 4) dogs were not operated upon and received all drugs in full dosage in order to test any direct toxic effect on normal kidneys. Biweekly gastric analysis, hemoglobin, white blood count, and daily serum creatinine were monitored. The dogs in group II that received the higher dose of cimetidine rejected the transplant earlier (mean survival, 20.4 days) than the dogs in the control group (mean survival, 37.8 days). No direct toxic effect from the drug was demonstrated in the control nontransplanted group. Cimetidine in high doses suppressed both basal and host stimulation secretion of gastric acid. In summary, the finding of increased rejection episodes and diminished survival after kidney transplantation in moderately immunosuppressed dogs that received cimetidine indicates that the use of this drug in transplantation is probably not safe until more is known about the immunological mechanisms involved in this situation.

The role of ultrasound in the diagnosis of kidney allograft rejection

Seventeen nephrectomized dogs underwent kidney transplantation from unrelated donors. Routine immunosuppressive therapy was administered. Serial ultrasound studies and biopsies and complete pathological examinations were performed and compared. A number of sonographic changes were observed within the renal parenchyma during rejection, some of which were present before a significant rise in serum creatinine levels. The medulla became enlarged due to edema, followed by growth of the rest of the kidney and thickening of the cortex. The cortical echoes became more sparsely distributed and either increased or decreased in amplitude; distribution was generalized or localized. During rejection, the corticomedullary boundary became indistinct. Later, a decrease in the renal sinus echoes was also noted. In 2 cases, perirenal fluid collections occurred as the result of renal rupture.

Long-term cranial mesenteric vein cannulation in the rat

A polyethylene-tipped silicone rubber catheter was placed in the cranial mesenteric vein of rats. Injections were made and blood withdrawn an average of seven times for each animal. Seventeen of 20 (85%) catheters remained patent for 3 weeks.

Study of the protective effect of methylprednisolone, furosemide, and mannitol on ischemically damaged kidneys

Canine kidneys subjected to 90 min of warm ischemia (37 degrees C) were protected by the administration of methylprednisolone but not by furosemide or mannitol. There was no protective effect observed through the vasodilating or diuretic effect of furosemide in the ischemic canine kidney. Mannitol-induced diuresis before warm ischemia also did not prove to be beneficial for severely ischemic kidneys. Methylprednisolone (30 mg/kg) given 2 h prior to warm ischemia prevented irreversible kidney damage observed in the control and experimental groups. By day 8 the serum creatinine and creatinine clearance returned to normal levels.