Enhancement of the Desorption Properties of LiAlH4 by the Addition of LaCoO3

The high hydrogen storage capacity (10.5 wt.%) and release of hydrogen at a moderate temperature make LiAlH₄ an appealing material for hydrogen storage. However, LiAlH₄ suffers from slow kinetics and irreversibility. Hence, LaCoO₃ was selected as an additive to defeat the slow kinetics problems of LiAlH₄. For the irreversibility part, it still required high pressure to absorb hydrogen. Thus, this study focused on the reduction of the onset desorption temperature and the quickening of the desorption kinetics of LiAlH₄. Here, we report the different weight percentages of LaCoO₃ mixed with LiAlH₄ using the ball-milling method. Interestingly, the addition of 10 wt.% of LaCoO₃ resulted in a decrease in the desorption temperature to 70 °C for the first stage and 156 °C for the second stage. In addition, at 90 °C, LiAlH₄ + 10 wt.% LaCoO₃ can desorb 3.37 wt.% of H₂ in 80 min, which is 10 times faster than the unsubstituted samples. The activation energies values for this composite are greatly reduced to 71 kJ/mol for the first stages and 95 kJ/mol for the second stages compared to milled LiAlH₄ (107 kJ/mol and 120 kJ/mol for the first two stages, respectively). The enhancement of hydrogen desorption kinetics of LiAlH₄ is attributed to the in situ formation of AlCo and La or La-containing species in the presence of LaCoO₃, which resulted in a reduction of the onset desorption temperature and activation energies of LiAlH₄.

Boosting the Dehydrogenation Properties of LiAlH4 by Addition of TiSiO4

Given its significant gravimetric hydrogen capacity advantage, lithium alanate (LiAlH₄) is regarded as a suitable material for solid-state hydrogen storage. Nevertheless, its outrageous decomposition temperature and slow sorption kinetics hinder its application as a solid-state hydrogen storage material. This research's objective is to investigate how the addition of titanium silicate (TiSiO₄) altered the dehydrogenation behavior of LiAlH₄. The LiAlH₄-10 wt% TiSiO₄ composite dehydrogenation temperatures were lowered to 92 °C (first-step reaction) and 128 °C (second-step reaction). According to dehydrogenation kinetic analysis, the TiSiO₄-added LiAlH₄ composite was able to liberate more hydrogen (about 6.0 wt%) than the undoped LiAlH₄ composite (less than 1.0 wt%) at 90 °C for 2 h. After the addition of TiSiO₄, the activation energies for hydrogen to liberate from LiAlH₄ were lowered. Based on the Kissinger equation, the activation energies for hydrogen liberation for the two-step dehydrogenation of post-milled LiAlH₄ were 103 and 115 kJ/mol, respectively. After milling LiAlH₄ with 10 wt% TiSiO₄, the activation energies were reduced to 68 and 77 kJ/mol, respectively. Additionally, the scanning electron microscopy images demonstrated that the LiAlH₄ particles shrank and barely aggregated when 10 wt% of TiSiO₄ was added. According to the X-ray diffraction results, TiSiO₄ had a significant effect by lowering the decomposition temperature and increasing the rate of dehydrogenation of LiAlH₄ via the new active species of AlTi and Si-containing that formed during the heating process.

Improved Dehydrogenation Properties of LiAlH4 by Addition of Nanosized CoTiO3

Despite the application of lithium aluminium hydride (LiAlH4) being hindered by its sluggish desorption kinetics and unfavourable reversibility, LiAlH4 has received special attention as a promising solid-state hydrogen storage material due to its hydrogen storage capacity (10.5 wt.%). In this work, investigated for the first time was the effect of the nanosized cobalt titanate (CoTiO3) which was synthesised via a solid-state method on the desorption behaviour of LiAlH4. Superior desorption behaviour of LiAlH4 was attained with the presence of a CoTiO3 additive. By means of the addition of 5, 10, 15 and 20 wt.% of CoTiO3, the initial desorption temperature of LiAlH4 for the first stage was reduced to around 115−120 °C and the second desorption stage was reduced to around 144−150 °C, much lower than for undoped LiAlH4. The LiAlH4-CoTiO3 sample also presents outstanding desorption kinetics behaviour, desorbing hydrogen 30−35 times faster than undoped LiAlH4. The LiAlH4-CoTiO3 sample could desorb 3.0−3.5 wt.% H2 in 30 min, while the commercial and milled LiAlH4 desorbs <0.1 wt.% H2. The apparent activation energy of the LiAlH4-CoTiO3 sample based on the Kissinger analysis was decreased to 75.2 and 91.8 kJ/mol for the first and second desorption stage, respectively, lower by 28.0 and 24.9 kJ/mol than undoped LiAlH4. The LiAlH4-CoTiO3 sample presents uniform and smaller particle size distribution compared to undoped LiAlH4, which is irregular in shape with some agglomerations. The experimental results suggest that the CoTiO3 additive promoted notable advancements in the desorption performance of LiAlH4 through the in situ-formed AlTi and amorphous Co or Co-containing active species that were generated during the desorption process.

Prevalence of hypertension and its risk factors among cotton textile workers in low- and middle-income countries: a systematic review

OBJECTIVE

The objective of this study was to evaluate the prevalence of hypertension and its risk factors among adult cotton textile workers in low- and middle-income countries (LMICs).

STUDY DESIGN

Systematic review.

METHODS

A review of English articles was performed between January 1, 2000, and December 31, 2021, using the following databases: PubMed/MEDLINE, Scopus, Web of Science, and Cochrane Library. Studies that measure the prevalence and risk factors of hypertension among adult cotton textile workers in LMICs were included. Extraction of articles and quality assessment of included studies were performed independently by two authors using the Mixed Methods Appraisal Tool checklist.

RESULTS

Of 2476 titles screened after duplication, 50 studies were shortlisted for full-text review, and a total of 10 studies were included. Of those 10 studies, seven were carried out in India, one in Indonesia, Iraq, and Iran. Using Stata version 6, the pooled prevalence of hypertension among the cotton textile workers was 18.0% (95% confidence interval: 11.0-25.0, random effect model: I² = 97.12%). Classic risk factors, including age, family history of hypertension, alcohol consumption, body mass index, and high waist-to-hip ratio, were recounted, whereas peculiar to the settings, noise level, improper use of earplugs, duration of noise exposure, working duration, and working in weaving section were reported.

CONCLUSION

The limited available evidence indicates a significant prevalence of hypertension among cotton workers in LMICs. In the wave of double burden of non-communicable diseases in developing countries, considering context-specific risk factors is critical in controlling hypertension by prioritizing organizational plans and policies to optimize workers' health.

PROSPERO REGISTRATION NUMBER

CRD42020167175.

Influence of Nanosized CoTiO3 Synthesized via a Solid-State Method on the Hydrogen Storage Behavior of MgH2

Magnesium hydride (MgH₂) has received outstanding attention as a safe and efficient material to store hydrogen because of its 7.6 wt.% hydrogen content and excellent reversibility. Nevertheless, the application of MgH₂ is obstructed by its unfavorable thermodynamic stability and sluggish sorption kinetic. To overcome these drawbacks, ball milling MgH₂ is vital in reducing the particle size that contribute to the reduction of the decomposition temperature. However, the milling process would become inefficient in reducing particle sizes when equilibrium between cold-welding and fracturing is achieved. Therefore, to further ameliorate the performance of MgH₂, nanosized cobalt titanate (CoTiO₃) has been synthesized using a solid-state method and was introduced to the MgH₂ system. The different weight percentages of CoTiO₃ were doped to the MgH₂ system, and their catalytic function on the performance of MgH₂ was scrutinized in this study. The MgH₂ + 10 wt.% CoTiO₃ composite presents the most outstanding performance, where the initial decomposition temperature of MgH₂ can be downshifted to 275 °C. Moreover, the MgH₂ + 10 wt.% CoTiO₃ absorbed 6.4 wt.% H₂ at low temperature (200 °C) in only 10 min and rapidly releases 2.3 wt.% H₂ in the first 10 min, demonstrating a 23-times-faster desorption rate than as-milled MgH₂ at 300 °C. The desorption activation energy of the 10 wt.% CoTiO₃-doped MgH₂ sample was dramatically lowered by 30.4 kJ/mol compared to undoped MgH₂. The enhanced performance of the MgH₂-CoTiO₃ system is believed to be due to the in situ formation of MgTiO₃, CoMg₂, CoTi₂, and MgO during the heating process, which offer a notable impact on the behavior of MgH₂.

Study of the Hydrogen Storage Properties and Catalytic Mechanism of a MgH2-Na3AlH6 System Incorporating FeCl3

In this work, the catalytic effects of FeCl₃ toward the hydrogen storage properties of the MgH₂-Na₃AlH₆ composite were investigated for the first time. The temperature-programed desorption results indicated that the onset temperature of the hydrogen release of a 10 wt % FeCl₃-doped MgH₂-Na₃AlH₆ composite was ∼30 °C lower than that of the undoped MgH₂-Na₃AlH₆ composite. The addition of FeCl₃ into the MgH₂-Na₃AlH₆ composite resulted in improved absorption and desorption kinetics performance. The absorption/desorption kinetics measurements at 320 °C (under 33 and 1 atm hydrogen pressure, respectively) indicated that within 10 min, the doped sample absorbed ∼4.0 wt % and desorbed ∼1.5 wt % hydrogen. By comparison, the undoped sample absorbed only ∼2.1 wt % and desorbed only ∼0.6 wt % hydrogen under the same conditions and time. Comparably, the apparent activation energy value of the doped composite is 128 kJ/mol, which is 12 kJ/mol lower than that of the undoped composite (140 kJ/mol). The formation of the new species of MgCl₂ and Fe in the doped composite was detected from X-ray diffraction analysis after heating and absorption processes. These two components were believed to play a vital role in reducing the decomposition temperature and kinetics enhancement of the MgH₂-Na₃AlH₆ composite.

His resynchronization therapy produces more physiological ventricular repolarisation compared with biventricular pacing

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation

BACKGROUND

Biventricular pacing (BVP) is known to shorten activation time in patients with heart failure and left bundle branch block (LBBB) but its effects on repolarisation are not well studied. His bundle pacing (HBP) can correct LBBB to deliver cardiac resynchronization therapy (HBP-CRT), producing more physiological ventricular activation time and pattern than BVP. It is not known whether this translates to more physiological repolarisation, and if so whether the effect is mediated through its effects on activation.

PURPOSE

We measured the effects of HBP-CRT and BVP on left ventricular repolarisation using non-invasive epicardial mapping (ECGI).

METHODS

Patients were recruited in two groups. 1) Patients scheduled for clinically indicated BVP procedures for heart failure with LBBB, 2) Individuals with narrow QRS, normal ventricular function and intact conduction systems. Using non-invasive electrocardiographic imaging, we identified patients with LBBB in whom HBP shortened ECGI-derived left ventricular (LV) activation time by &gt;10ms. We compared the effects of HBP and BVP on ECGI-derived dispersion of LV repolarisation times and activation-recovery intervals (a surrogate for action potential duration).

RESULTS

21 patients in whom HBP shortened LV activation time by &gt;10ms and an equal number of individuals with narrow intrinsic QRS were recruited. LV repolarisation dispersion was reduced by HBP-CRT (-42.0 ms, 95% confidence interval (CI): -52.3 to -31.7 ms, p &lt;0.001) but not by BVP (11.9 ms, 95% CI: -6.24 to 30.1 ms, p = 0.182). The mean within-patient change in LV repolarisation dispersion from BVP to HBP-CRT was -56.5 ms (95% CI: -70.5 to -42.5 ms, p &lt; 0.001). LV repolarisation dispersion with HBP-CRT was not different from individuals with narrow intrinsic QRS (2.75 ms, 95% CI: -16.2 to 21.7 ms, p = 0.981). The magnitude of reduction in LV repolarisation dispersion with HBP-CRT from intrinsic LBBB appeared similar to the magnitude of LV activation time shortening (-54.9 ms, 95% CI: -68.2 to -41.6 ms, p &lt; 0.001). However, LV activation-recovery interval dispersion was also reduced by HBP-CRT (-44.3 ms, 95% CI: -69.2 to -19.3 ms, p &lt; 0.001). Repolarisation mapping demonstrated normalisation of repolarisation pattern by HBP-CRT.

CONCLUSIONS

HBP-CRT can normalise repolarisation dispersion, producing more physiological repolarisation compared with BVP, which does not resolve the repolarisation abnormality of LBBB. HBP-CRT improves repolarisation through both activation resynchronization and modulation of action-potential duration. If these acute results translate to longer term outcomes, HBP-CRT may reduce the risk of ventricular arrhythmias in heart failure with LBBB to a greater extent than BVP. Abstract Figure. Epicardial Repolarisation Maps

Influence of K2NbF7 Catalyst on the Desorption Behavior of LiAlH4

In this study, the modification of the desorption behavior of LiAlH4 by the addition of K2NbF7 was explored for the first time. The addition of K2NbF7 causes a notable improvement in the desorption behavior of LiAlH4. Upon the addition of 10 wt.% of K2NbF7, the desorption temperature of LiAlH4 was significantly lowered. The desorption temperature of the LiAlH4 + 10 wt.% K2NbF7 sample was lowered to 90°C (first-stage reaction) and 149°C (second-stage reaction). Enhancement of the desorption kinetics performance with the LiAlH4 + 10 wt.% K2NbF7 sample was substantiated, with the composite sample being able to desorb hydrogen 30 times faster than did pure LiAlH4. Furthermore, with the presence of 10 wt.% K2NbF7, the calculated activation energy values for the first two desorption stages were significantly reduced to 80 and 86 kJ/mol; 24 and 26 kJ/mol lower than the as-milled LiAlH4. After analysis of the X-ray diffraction result, it is believed that the in situ formation of NbF4, LiF, and K or K-containing phases that appeared during the heating process promoted the amelioration of the desorption behavior of LiAlH4 with the addition of K2NbF7.

Dehydrogenation Properties and Catalytic Mechanism of the K2NiF6-Doped NaAlH4 System

The K₂NiF₆ catalytic effect on the NaAlH₄ dehydrogenation properties was studied in this work. The desorption temperature was studied using temperature-programmed desorption and exhibited a lower onset hydrogen release after doped with different wt % of K₂NiF₆ (5, 10, 15 and 20 wt %). It was found that the NaAlH₄ doped with 5 wt % K₂NiF₆ showed the optimal value that can reduce the onset desorption temperature of about 160 °C compared to 190 °C for the milled NaAlH₄. The NaAlH₄ + 5 wt % K₂NiF₆ sample showed faster desorption kinetics where 1.5 wt % of hydrogen was released in 30 min at 150 °C. In contrast, the milled NaAlH₄ only released about 0.2 wt % within the same time and temperature. From the Kissinger analysis, the apparent activation energy was 114.7 kJ/mol for the milled NaAlH₄ and 89.9 kJ/mol for the NaAlH₄-doped 5 wt % K₂NiF₆, indicating that the addition of K₂NiF₆ reduced the activation energy for hydrogen desorption of NaAlH₄. It is deduced that the new phases of AlNi, NaF, and KH that were formed in situ during the dehydrogenation process are the key factors for the improvement of dehydrogenation properties of NaAlH₄.

Comparison of risk stratification tools in predicting outcomes of patients with higher-risk myelodysplastic syndromes treated with azanucleosides

Established prognostic tools in patients with myelodysplastic syndromes (MDS) were largely derived from untreated patient cohorts. Although azanucleosides are standard therapies for higher-risk (HR)-MDS, the relative prognostic performance of existing prognostic tools among patients with HR-MDS receiving azanucleoside therapy is unknown. In the MDS Clinical Research Consortium database, we compared the prognostic utility of the International Prognostic Scoring System (IPSS), revised IPSS (IPSS-R), MD Anderson Prognostic Scoring System (MDAPSS), World Health Organization-based Prognostic Scoring System (WPSS) and the French Prognostic Scoring System (FPSS) among 632 patients who presented with HR-MDS and were treated with azanucleosides as the first-line therapy. Median follow-up from diagnosis was 15.7 months. No prognostic tool predicted the probability of achieving an objective response. Nonetheless, all five tools were associated with overall survival (OS, P=0.025 for the IPSS, P=0.011 for WPSS and P<0.001 for the other three tools). The corrected Akaike Information Criteria, which were used to compare OS with the different prognostic scoring systems as covariates (lower is better) were 4138 (MDAPSS), 4156 (FPSS), 4196 (IPSS-R), 4186 (WPSS) and 4196 (IPSS). Patients in the highest-risk groups of the prognostic tools had a median OS from diagnosis of 11-16 months and should be considered for up-front transplantation or experimental approaches.

Household Animal and Human Medicine Use and Animal Husbandry Practices in Rural Bangladesh: Risk Factors for Emerging Zoonotic Disease and Antibiotic Resistance

Animal antimicrobial use and husbandry practices increase risk of emerging zoonotic disease and antibiotic resistance. We surveyed 700 households to elicit information on human and animal medicine use and husbandry practices. Households that owned livestock (n = 265/459, 57.7%) reported using animal treatments 630 times during the previous 6 months; 57.6% obtained medicines, including antibiotics, from drug sellers. Government animal healthcare providers were rarely visited (9.7%), and respondents more often sought animal health care from pharmacies and village doctors (70.6% and 11.9%, respectively), citing the latter two as less costly and more successful based on past performance. Animal husbandry practices that could promote the transmission of microbes from animals to humans included the following: the proximity of chickens to humans (50.1% of households reported that the chickens slept in the bedroom); the shared use of natural bodies of water for human and animal bathing (78.3%); the use of livestock waste as fertilizer (60.9%); and gender roles that dictate that females are the primary caretakers of poultry and children (62.8%). In the absence of an effective animal healthcare system, villagers must depend on informal healthcare providers for treatment of their animals. Suboptimal use of antimicrobials coupled with unhygienic animal husbandry practices is an important risk factor for emerging zoonotic disease and resistant pathogens.

Mayo prognostic model for WHO-defined chronic myelomonocytic leukemia: ASXL1 and spliceosome component mutations and outcomes

We evaluated the prognostic relevance of several clinical and laboratory parameters in 226 Mayo Clinic patients with chronic myelomonocytic leukemia (CMML): 152 (67%) males and median age 71 years. At a median follow-up of 15 months, 166 (73%) deaths and 33 (14.5%) leukemic transformations were documented. In univariate analysis, significant risk factors for survival included anemia, thrombocytopenia, increased levels of white blood cells, absolute neutrophils, absolute monocyte count (AMC), absolute lymphocytes, peripheral blood and bone marrow blasts, and presence of circulating immature myeloid cells (IMCs). Spliceosome component (P=0.4) and ASXL1 mutations (P=0.37) had no impact survival. On multivariable analysis, increased AMC (>10 × 10(9)/l, relative risk (RR) 2.5, 95% confidence interval (CI) 1.7-3.8), presence of circulating IMC (RR 2.0, 95% CI 1.4-2.7), decreased hemoglobin (<10 g/dl, RR 1.6, 99% CI 1.2-2.2) and decreased platelet count (<100 × 10(9)/l, RR 1.4, 99% CI 1.0-1.9) remained significant. Using these four risk factors, a new prognostic model for overall (high risk, RR 4.4, 95% CI 2.9-6.7; intermediate risk, RR 2.0, 95% CI 1.4-2.9) and leukemia-free survival (high risk, RR 4.9, 95% CI 1.9-12.8; intermediate risk, RR 2.6, 95% CI 1.1-5.9) performed better than other conventional risk models and was validated in an independent cohort of 268 CMML patients.

Screening of Yemeni medicinal plants for antibacterial and cytotoxic activities

Ethanolic extracts of 20 selected plant species used by Yemeni traditional healers to treat infectious diseases were screened for their antibacterial activity against both Gram-positive and Gram-negative bacteria, as well as for cytotoxic activity. Fourteen of the ethanolic extracts showed variable degrees of antibacterial activity. The active ethanolic extracts were partitioned between ethyl acetate and water for a first separation. The ethyl acetate extract of Lawsonia inermis was found to be the most active one against all bacteria in the test system. Other promising results could be obtained from extracts of Aloe perryi, Indigofera oblongifolia, Meriandra benghalensis and Ziziphus spina christi. Additionally, the ethanolic extracts of the 20 plants under investigation were tested for their cytotoxic effects on FL-cells using the neutral red assay. Extracts of Calotropis procera, Chenopodium murale, Pulicaria orientalis, Tribulus terrestris and Withania somniferum displayed a remarkable activity.

Haemolytic potential of three chemotherapeutic agents and aspirin in glucose-6-phosphate dehydrogenase deficiency

The potential haemolytic effect of three chemotherapeutic drugs and aspirin was tested in vitro by gluthathione stability tests. Blood was collected from the local population of Basra, Iraq where previous studies had found a high frequency of glucose-6-phosphate dehydrogenase (G6PD) deficiency. Primaquine, chloramphenicol and sulfanilamide caused significant concentration-dependent reductions of glutathione levels in G6PD-deficient red cells when compared to normal red cells. Acetylsalicylic acid had no effect on glutathione level. The G6PD-deficient erythrocytes behaved as previously reported, probably due to similar patterns in the distribution of its variants. Studies on each local variant are warranted and new drugs should be tested for haemolytic potential prior to their introduction in areas where the deficiency is common.

Inhibition of chemiluminescence response of human mononuclear cells and suppression of mitogen-induced proliferation of spleen lymphocytes of mice by hispolon and hispidin

The effects of two phenolic compounds, hispolon and hispidin isolated from fruit bodies of the basidiomycete Inonotus hispidus (Bull. ex Fr.) Karst, were investigated on the chemiluminescence response by LPS- or zymosan-activated human mononuclear cells (MNC) and on the concanavalin A-induced proliferation of spleen lymphocytes of mouse in vitro. Both compounds showed inhibitory activity in the chemiluminescence-test with an IC50 (the concentration of test compound causing 50% effect) ranging from 4.4 to 4.6 micrograms/ml (20.3 to 21.2 microM) for hispolon and < 0.1 to 1.5 micrograms/ml (from < 0.4 microM to 6.0 microM) for hispidin. Antiproliferative effects have been achieved in the lymphocyte transformation test (LTT) by hispolon with an IC50 of 3.4 micrograms/ml (15.5 microM).

Oxacillin-hydrolysing beta-lactamases. A comparative analysis at nucleotide and amino acid sequence levels

We have extended the sequence of the OXA-2 beta-lactamase which together with S1 mapping has enabled us to identify the promoter site for this gene. This lies in a region that is found upstream from a variety of resistance genes on different plasmids; each gene appears to have been inserted at the same specific site and to be expressed from the same promoter. The ancestral plasmid thus appears to function as a natural expression vector. The sequence of the recombination site at the 5' end of the OXA-2 gene shows a marked similarity with the attP sequence of lambda. DNA-probe analysis confirmed that the OXA-2 and OXA-3 beta-lactamases are related, and indicated no similarity with other beta-lactamase genes. However, a comparison of amino acid sequences demonstrates that the OXA-2, OXA-1 and PSE-2 beta-lactamases show some similarities to the typical class A enzymes, especially in the central helical domain of the latter, which is largely responsible for forming the active site of the enzyme. The three oxacillinases also show marked amino acid sequence similarity with the product of a regulatory gene, blaR1, required for beta-lactamase induction in Bacillus licheniformis.

Comparison of the effects of therapeutic doses of meptazinol and a dextropropoxyphene/paracetamol mixture alone and in combination with ethanol on ventilatory function and saccadic eye movements

The respiratory and psychomotor effects of a single oral dose of meptazinol (200 mg) and dextropropoxyphene (65 mg)/paracetamol (650 mg) mixture, was compared alone and in combination with ethanol (0.8 g kg-1). Peak saccade velocity following meptazinol or the dextropropoxyphene/paracetamol mixture was not significantly different from placebo. When each of the treatments was followed by ethanol administration, a significant decrease in saccade velocity (P less than 0.01) was seen. Given alone, neither of the analgesic drugs produced a significant change in the slope of the ventilatory response to hypercapnia. Ethanol did not affect the ventilatory response to hypercapnia when given alone or in combination with meptazinol, but when given with the dextropropoxyphene/paracetamol mixture, a significant reduction in the slope of the ventilatory response to hypercapnia occurred at 1.5 h (P less than 0.05) and 2 h (P less than 0.01) after administration of the analgesic drug. No pharmacokinetic interaction was demonstrated between ethanol and meptazinol or the dextropropoxyphene/paracetamol mixture in the doses used. In contrast to meptazinol, the dextropropoxyphene/paracetamol mixture interacts with ethanol on the ventilatory function.

Radical cure of pilonidal sinus by a transposition rhomboid flap

A new operation for pilonidal sinus is described. This utilizes a rhomboid transposition flap to cover the defect left after radical excision. The results show healing by first intention in 29 out of 30 patients. No patient remained in hospital for more than ten days. Minor infection took place in five cases and major infection in one case. Patients have been followed for up to three years. No recurrence has yet been encountered. The reasons for the success of this operation are discussed.