An analytics-based heuristic decomposition of a bilevel multiple-follower cutting stock problem.

This paper presents a new class of multiple-follower bilevel problems and a heuristic approach to solving them. In this new class of problems, the followers may be nonlinear, do not share constraints or variables, and are at most weakly constrained. This allows the leader variables to be partitioned among the followers. We show that current approaches for solving multiple-follower problems are unsuitable for our new class of problems and instead we propose a novel analytics-based heuristic decomposition approach. This approach uses Monte Carlo simulation and k-medoids clustering to reduce the bilevel problem to a single level, which can then be solved using integer programming techniques. The examples presented show that our approach produces better solutions and scales up better than the other approaches in the literature. Furthermore, for large problems, we combine our approach with the use of self-organising maps in place of k-medoids clustering, which significantly reduces the clustering times. Finally, we apply our approach to a real-life cutting stock problem. Here a forest harvesting problem is reformulated as a multiple-follower bilevel problem and solved using our approach.

Cutting uncertain stock and vehicle routing in a sustainability forestry harvesting problem.

Sustainable forest management is concerned with the management of forests according to the principles of sustainable development. As a contribution to the field, this paper combines the Vehicle Routing Problem (VRP) (in which the vehicles are harvesters) with the Multiple Stock Size Cutting Stock Problem under uncertainty (in which the stock is logs). We present an Integer Linear Program that dynamically combines the cutting of the uncertain stock with vehicle routing, and uses it to address real-life problems. In experiments on real data from the forestry harvesting industry, we show that it outperforms a commonly used metaheuristic algorithm.

Genetic studies in the Nigerian population implicate an MSX1 mutation in complex oral facial clefting disorders.

BACKGROUND: Orofacial clefts are the most common malformations of the head and neck, with a worldwide prevalence of 1 in 700 births. They are commonly divided into CL(P) and CP based on anatomic, genetic, and embryologic findings. A Nigerian craniofacial anomalies study (NigeriaCRAN) was set up in 2006 to investigate the role of gene-environment interaction in the origin of orofacial clefts in Nigeria. SUBJECTS AND METHODS: DNA isolated from saliva from Nigerian probands was used for genotype association studies and direct sequencing of cleft candidate genes: MSX1 , IRF6 , FOXE1, FGFR1 , FGFR2 , BMP4 , MAFB, ABCA4 , PAX7, and VAX1 , and the chromosome 8q region. RESULTS: A missense mutation A34G in MSX1 was observed in nine cases and four HapMap controls. No other apparent causative variations were identified. Deviation from Hardy Weinberg equilibrium (HWE) was observed in these cases (p = .00002). A significant difference was noted between the affected side for unilateral CL (p = .03) and bilateral clefts and between clefts on either side (p = .02). A significant gender difference was also observed for CP (p = .008). CONCLUSIONS: Replication of a mutation previously implicated in other populations suggests a role for the MSX1 A34G variant in the development of CL(P).

Successful separation of two pairs of conjoined twins in Ile Ife, Nigeria: case reports.

Conjoined twins are rare phenomena occurring in one in 1 in 50,000 live births. Successful surgical separation of conjoined twins is a major undertaking requiring careful planning by a multidisciplinary team. Reports of seperation of joined twins in developing countries like Nigeria are rare. Ten cases of conjoined twins were separated between 1936 and January 2003 (including the authors two new cases). There were five omphalopagus, two pygopagus, two heterpagus and one ishiopagus twins. Three underwent emergency separation with 83.3% mortality while seven underwent elective seperation with 64.3% survival. The overall mortality rate was 50%. Despite the absence of advanced technological resource selected group of conjoined twins can be successfully separated in a developing country like Nigeria. An improvement in facilities and availability of trained personnel in likely to be associated with improved outcome.

Intrauterine intussusception causing intestinal atresia.

The patient presented at the age of 2 days with persistent bilious vomiting, failure to pass meconium and urine, and progressive abdominal distension dating from birth, and a clinical diagnosis of intestinal obstruction was made. This was confirmed by plain abdominal radiographs. At laparotomy atresia of the terminal ileum was found. The proximal and distal segments of the bowel ended blindly and there was a V-shaped defect in the adjoining mesentery. The blind ends were resected and an end-to-back anastomosis was performed. The lumen of the resected distal segment contained an intussusceptum.

Acute generalized peritonitis in African children: assessment of severity of illness using modified APACHE II score.

BACKGROUND: Generalized surgical acute abdomen is a significant cause of morbidity and mortality among children. Severity assessment is useful in order to prioritize treatment and reduce complications. Patients with a high severity score are often faced with high morbidity and mortality, thus, requiring more intensive treatment than those with low severity scores. The purpose of the present study was to assess the severity of the acute abdomen in paediatric patients using a modification of the acute physiological and chronic ill-health evaluation II score (APACHE II). METHODS: Children admitted and operated on for generalized acute abdomen over a period of 7 years from January 1993 to December 1999 were prospectively studied. A study proforma was drafted and demographic, clinical, preoperative, operative and postoperative data on each patient were entered. Each patient had severity of illness assessed using APACHE II parameters with minor modification to make it applicable to children. Postoperative outcome and severity of illness were compared to determine any correlation. RESULTS: There were 69 patients operated on within the period of the study. Age ranged from 3 months to 15 years, with a mean of 9.1 SD 4.3 years. Forty-two patients (61.2%) were male and 27 (39.8%) were female. Typhoid intestinal perforation accounted for 35 (50.7%) and intestinal obstruction with or without intestinal gangrene accounted for nine (13%). Modified APACHE II score ranged from 0 to 18, mean 8.5 SD 5. For survivors, the mean score was 8; for non-survivors, 13. Eight patients died (11.6%): four of 63 (6.4%) patients who scored 0-15 died; four of six (66.7%) patients who scored 16-18 (P < 00.05) died. A modified APACHE II score greater than 15 was associated with a significantly greater mortality. The data for postoperative morbidity and hospital stay were not conclusive. CONCLUSION: Although the APACHE II score was designed for adults, a modification can be suitably applied to predict mortality in children with generalized peritonitis. There will be a need to apply this to large number of patients in order to validate our finding.

Acute intestinal obstruction in Nigerian children.

Over a 7 year period, intestinal obstruction accounted for 41.7 per cent of abdominal emergencies and 1.03 per cent of all paediatric admissions at the Obafemi Awolowo University Teaching Hospital in Ile-Ife, Nigeria. Of the total 76 cases of acute intestinal obstruction, intussuception was seen in 34 (44.7%), peritoneal adhesions in 17 (22.4%), obstructed hernia in 14 (18.4%), roundworm impaction in 4 (5.3%), volvulus in 3 (4.0%) while faecal impaction and mesenteric cysts were encountered in 2 children each (2.6%). Generally the patients presented late to the hospital and this accounted for the high post-operative morbidity and prolonged hospital stay. Wound infection occurred in 21.1 per cent of patients and formed the commonest post-operative complication. The overall mortality was 21.1 per cent.

Anaesthesia for neonatal surgical emergencies in a semi-urban hospital, Nigeria.

OBJECTIVE: To establish the techniques of anaesthesia for neonatal surgical emergencies in a semi-urban hospital in Nigeria, assess their adequacy and make recommendations to improve our practice. DESIGN: Retrospective study. SETTING: Obafemi Awolowo University Teaching Hospital, Ile-lfe, Nigeria, from January 1990 to December 2000. SUBJECTS: One hundred neonates aged one to twenty eighty days. RESULTS: One hundred neonatal surgical emergencies were operated but only 76 case notes were available for review. Three hundred and fifty eight elective neonatal surgeries were done during the same period. The ASA classification were: ASA IE=10, 2E=25, 3E=28, 4E =12 and 5E=1. The mean weight was 2.66+/ 0.52 kg. Over 95% of the cases were done under general anaesthesia. Anorectal malformations and intestinal obstruction were the most common indications for surgery (64.5%). Nurse anaesthetists gave over 50% of the anaesthetics. Peri-operative adverse events such as tachycardia, respiratory distress, aspiration and hypothermia were recorded in 11.8% of the cases. Mortality was 39.2%. CONCLUSION: General anaesthesia is still the main technique of anaesthesia and mortality following surgery is still high. Efforts should be made to train appropriate personnel to provide improved care and thereby reduce morbidity and mortality.

Radiologic and sonographic evaluation of intra-abdominal abscesses in a Nigerian population.

A prospective study to evaluate the radiologic and sonographic features of intraabdominal abscesses in a mixed Nigerian population was undertaken. 30 patients with suspected abscesses were studied and a total of 70 abdominal abscess sites were confirmed at surgery or during autopsy in 22 patients. The more common abscess sites were the paracolic and pelvic areas. Typhoid enteritis, perforated duodenal ulcer and septicaemia were the aetiological factors in 54%, 13.6% and 13.6% respectively. The more common radiological feature was that of extraluminal gas vesicles and relatively echo free collections were identified during ultrasound. Poor prognosis was associated with typhoid enteritis, multiple abscess sites and acute renal failure.

Prognostic factors in childhood inguinal hernia at Wesley Guild Hospital, Ilesa, Nigeria.

OBJECTIVE: To determine the pattern, outcome and the prognostic factors in childhood inguinal hernia. DESIGN: A five-year prospective study. SETTING: Wesley Guild Hospital, Ilesa, Nigeria. RESULTS: Two hundred and eight patients presented with 237 inguinal or inguinoscrotal hernias. Seventy one per cent were aged five years and below and 24% were infants. Male patients accounted for 94.7% of the cases. Mean duration of symptoms was 1.2 years in the patients without hernia complication but less than five months in complicated hernia. Symptoms of complication such as vomiting and abdominal pain occurred in 7.8% to 15% of children mainly under five years. Inguinoscrotal hernia was diagnosed in 76.5% of cases, of whom 53.8% presented on the right side, 32.3% on the left and 14% bilaterally. Undescended testes, low birthweight, anaemia and malnutrition presented in 22.6% of the cases. Incarcerated hernia was diagnosed in 16 patients (7.7%), all males, with ages ranging from two weeks to two years. Eighty nine per cent of the patients were operated upon as outpatients. Undescended testes constituted the commonest associated operative finding in about five per cent of the patients and one patient had non-rotation of the gut involved in strangulation. Statistical analysis showed that clinical pattern, outcome and the incidence of postoperative complication were significantly dependent on the sex, age and presence hernia complications. CONCLUSION: Inguinoscrotal hernia is commoner and predominantly in the male, majority of whom were below the age of five years. Most associated clinical and operative findings occurred in infants. Incarceration occurred more significantly in infants. Wound infection was the commonest complication. This and other complications were significantly affected by the age of the patients and incarceration.

Gastrointestinal duplications in Ile-Ife, Nigeria.

BACKGROUND: Gastrointestinal duplications are rare congenital malformations that commonly present within the first year of life. When they present in older age groups, diagnosis is often difficult. This difficulty derives from the lack of specific clinical features attributable to these lesions OBJECTIVES: To document the challenges posed to surgeons by gastrointestinal duplications in different parts of the world and to report our experience in its management in Ile-Ife, Nigeria. DESIGN: A retrospective study. It involved a study of the clinical records of all patients diagnosed to have gastrointestinal duplication in our hospital. SETTING: A Paediatric and General Surgical unit, University of Ile-Ife Teaching Hospital, Ile-Ife, Nigeria.. RESULTS: Five patients were diagnosed to have gastrointestinal duplications over the of the study. The ate, ranged from 28 days to 52 years. There were four males and one female. One patient presented within the first month of life. The others presented after the age of one year. There were two gastric, two ileal and one rectal duplication. All had the cystic variety of duplication. Three of the patients had excision, one had mucosal stripping and one had internal drainage of the duplication. The outcome was satisfactory in all of them. CONCLUSION: Duplications tend to present at a much older-age group in our environment. Early diagnosis therefore depends on a high index of suspicion and every surgeon operating in the abdomen must be familiar with the management of this condition.

Sources of intra-operative bacterial colonization of clean surgical wounds and subsequent post-operative wound infection in a Nigerian hospital.

The incidence of postsurgical clean wound infection in 101 consecutive operations was 1.98%. Staphylococci were the predominant bacteria cultured from the anterior nares of the patients and attending surgical personnel--and were found to colonize the wounds. The nasal carriage rates of Staphylococcus aureus amongst the patients and surgical staff were 12.1% and 17.% respectively. Group III and non-typeable (NT) S. aureus strains accounted for about 65% of S. aureus isolates cultured from the anterior nares. A low incidence of nasal carriage of S. aureus isolates correlated with low incidence of wound sepsis. The operating room air seemed considerably contaminated but this did not reflect in high incidence of postsurgical wound sepsis. Our results suggest patients microflora and operating room air were the major sources of intra-operative bacterial colonization of wound at this centre.

Management of oesophageal foreign bodies in children.

OBJECTIVE: To evaluate the pattern and outcome of management of retained oesophageal foreign bodies in children. DESIGN: Retrospective study. SETTING: Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, January 1991 to December 2000. SUBJECTS: One hundred and eight paediatric patients, aged 0-14 years managed for retained oesophageal foreign bodies. INTERVENTION: The foreign bodies were removed endoscopically, using either a larynoscope or a rigid oesophagoscope, under general anaesthesia. RESULTS: There were 108 patients, with a mean age of 3.0 +/- 0.8 years and age range of 23 days to 14 years. The male to female ratio was 1.5: 1. Sixty four (59.3%) patients were within 1-5 year age group. Coins constituted 79.6% of the retained foreign bodies. Over 90% of patients presented within the first four days of the incidence. The dominant complaints were drooling of saliva in 37 (40.2%) and difficulty in swallowing in 35 (38.1%) patients. The commonest sites of the foreign body retention were the upper third of oesophagus 52(48.2%) and the hypopharynx 36(33.3%). The main complications following the foreign body removal were oesophageal perforations 4(3.7%) and lacerations 16(15%). CONCLUSION: Retained oesophageal foreign body is a common childhood health hazard. Early diagnosis and prompt skillful removal are necessary for a satisfactory outcome.

Mesenteric cysts in Nigerians.

Mesenteric cysts are uncommon and are said to be rarer among blacks than in caucasians. We report six mesenteric cysts seen in five patients over a 9 1/2 year period with an incidence of one in 48,497 hospital admissions. there were three males and two females. Ultrasonography was carried out in three of our five cases. There is need to include mesenteric cyst in the differential diagnosis of an abdominal mass. Surgery was the mainstay of treatment. At laparotomy, five of the cysts were found in the mesentery of the small bowel. Simple enucleation was done in one patient while cyst resection with adjacent bowel was carried out in three patients. There were two cysts in the youngest patient and these were internally drained. All the patients did well with uneventful post-operative period with no mortality. Follow up had been from 14 months to 6 years.

Peri-umbilical cellulitis in Nigerian neonates.

A retrospective analysis was made of 32 neonates with peri-umbilical cellulitis seen at Wesley Guild Hospital, Ilesa, Nigeria from 1979 through 1989. All were full term and delivered after a normal pregnancy. The male:female ratio was 1.3:1. On admission, the mean (Standard Deviation) post-natal age, weight and duration of symptoms were 7.3 (2.7) days, 3.21 (0.5) kg, and 1.9 (1.3) days respectively. Major features were abdominal distension, extensive peri-umbilical induration and inflammation, and foul-smelling discharge. Most mother had antenatal care, but 60 pc were delivered at home or in the mission house. There were no recognisable maternal risk factors. Hot fomentation and unsterile materials applied to the cord were the apparent causative factors. The case fatality rate was very high (71.9 pc). Recommended treatment was antibiotics and surgical debridement. If hospital delivery were accessible to the less privileged poor, this highly lethal condition could be prevented by facilitating instruction in simple sterile cord care.

Malignant solid tumours in Nigerian children.

The subject of neoplasia in African children has received little or no attention within the past two decades. The current study retrospectively reviews malignant solid tumours in children from birth up to the age of 15 years over an 11 year period in Ile-Ife, Nigeria. During this period, 71 pc of solid tumours seen in children were malignant and boys were more often affected than girls. The peak incidence was between the ages of six and 13 years. Lymphoma was the commonest type of tumour, accounting for 72.6 pc of all malignant solid tumours and males predominated. All the rhabdomyosarcomas were seen in boys and the alveolar variant predominated. Osteogenic sarcoma and nephroblastoma were more often seen in girls. No primary brain tumour was seen.

Cervical teratoma in Nigeria children.

Cervical teratomas are uncommon tumours. Over an eight-year period, four cases of cervical teratomas were seen in children at the University Teaching Hospital, Ile-Ife, Nigeria. The children ranged in age from two weeks to nine years. In two patients the tumours were noticed at birth but in only one was it symptomatic to be the cause of hospitalization at the age of two weeks. The other two had the tumours for three and six years respectively and presented because of cosmetic embarrassment. All the tumours were easily resected at surgery and two showed an anatomical relationship to the thyroid gland. The post-operative course was uneventful in the four patients. The histopathology of the tumours have shown tissues from the three germ layers with neurological elements predominating in two and thyroid tissue present in the other two. Over a follow-up period varying from one to four years none of the children have demonstrated any abnormality of thyroid functions.

Primary tuberculous mastitis in a Nigerian woman.

Tubercolous mastitis is an uncommon lesion even in countries where the incidence of pulmonary and extrapulmonary tuberculosis is still very high. At the Ife University Teaching Hospital only one case of tuberculous mastitis has been seen over a ten-year period during which 671 breast biopsies were examined. This was in a 36-year old Nigerian woman who developed a left breast mass during pregnancy. She was seen after her delivery and was initially diagnosed as a case of carcinoma of the breast. Subsequent excisional biopsy and pathological examination of the mass confirmed tuberculosis of the breast. She has responded favourably to anti-tuberculous therapy.

Surgical audit in the developing countries.

Audit assures provision of good quality health service at affordable cost. To be complete therefore, surgical practice in the young developing countries, as elsewhere, must incorporate auditing. Peculiarities of the developing countries and insufficient understanding of auditing may be, however, responsible for its been little practised. This article, therefore, reviews the objectives, the commonly evaluated aspects, and the method of audit, and includes a simple model of audit cycle. It is hoped that it will kindle the idea of regular practice of quality assurance by surgeons working in the young developing nations and engender a sustainable interest.

Appraisal on fluid and electrolyte management in paediatric surgical patient.

Fluid and electrolyte disorders are common occurrences in Paediatric surgical practice. Despite this, the management of fluid and electrolyte imbalance in the paediatric surgical patients remains problematic. This is partly because authorities vary considerably in their recommendations for therapy, despite the great advances being attained in the understanding of the fluid and electrolyte homeostasis in the Paediatric age group. This has, in no doubt, resulted in a number of morbidity and mortality that could have been prevented based upon rational and acceptable recommendations for fluid and electrolyte therapy in children. In this review, the normal homeostasis, disorders and management of fluid and electrolyte and corrections of metabolic disorders in children are highlighted, with the aim to update the practice of fluid and electrolyte therapy in children.