A Morphometric Study of Olecranon Fossa of Adult Human Humerus of Bangladeshi Population.

Olecranon fossa is the largest fossa among the three fossae of the humerus. It is present in the lower end of the posterior surface just above the trochlea. Osteometry of olecranon fossa is important since their fractures occur in 10.0% of upper limb fractures. The aim of this study was to measure different parameters of olecranon fossa. This study was taken from 100 (right=43 and left=57) samples were selected through the purposive sampling technique for this cross-sectional descriptive study which was carried out in the Department of Anatomy, Mymensingh Medical College, Mymensingh, Bangladesh from July 2021 to June 2022. Any damaged, unossified bones or fractured bones were excluded. Data were tabulated and statistically analyzed using Microsoft Excel and SPSS software. The mean ±SD vertical diameter of the olecranon fossa of the right humeri was 16.858±2.623mm and the left humeri were 17.071±2.905mm. The mean ±SD width of the olecranon fossa of the right humeri was 24.239±2.520mm and the left humeri were 24.509±2.692mm. The mean ±SD maximum depth of the olecranon fossa of the right humeri was 13.442±1.688mm and the left humeri were 13.124±1.733mm. The anatomical knowledge of the olecranon fossa is beneficial for anthropologists, orthopedic surgeons and radiologists in cases of olecranon fractures of the humerus.

Anatomical Study of Bicipital Groove of Dry Adult Human Cadaveric Humerus in Bangladesh.

The bicipital groove is a groove on the anterior aspect of the proximal end of the humerus. It lies between the greater and lesser tubercles. The variations of this groove may lead to various pathologies of the biceps brachii tendon, one of the most common causes of shoulder pain. Hence, this study examines the various osteometric parameters of bicipital groove in the Bangladeshi population. This cross-sectional descriptive study was done on 100 dry adult human cadaveric humeri (43 right sides and 57 left sides) in the Department of Anatomy, Mymensingh Medical College, Bangladesh from July 2021 to June 2022. The length, maximum width and depth of the bicipital groove and the length of this groove's medial and lateral walls were measured using a digital Vernier slide caliper. Data were recorded in a predesigned data sheet separately and analyzed statistically using Microsoft Excel and SPSS. According to the present study, the mean±SD length of the bicipital groove of the right humeri was 66.646±11.563mm and the left humeri were 66.002±13.025mm. The mean±SD maximum width of the bicipital groove of the right humeri was 10.870±1.799mm and the left humeri were 11.480±1.402mm. The mean±SD depth of the bicipital groove of the right humeri was 4.242±0.655mm and the left humeri were 4.452±0.854mm. The mean±SD medial wall length of the bicipital groove of the right humeri was 60.671±12.360mm and the left humeri were 59.161±13.660mm. The mean±SD lateral wall length of the bicipital groove of the right-sided humeri was 64.996±11.611mm and the left humeri were 64.074±13.115mm. It is expected that this osteometric study of bicipital groove among the Bangladeshi population will be very helpful for clinical anatomists, orthopaedic surgeons, anthropologists and radiologists.

Anatomical Study of Number, Location and Position of Nutrient Foramina of Fully Ossified Dry Human Humerus.

The nutrient foramen is the natural opening present in the shaft of the humerus. It passes the nutrient artery to the medullary cavity. The nutrient artery is the chief artery that enters the bone through a nutrient foramen to provide nutrition for its growth. It plays an important role in healing during fracture and trauma and is also important for bone grafting. This study aimed to determine the common location, position and number of nutrient foramina of fully ossified dry human humerus. One hundred samples (right- 43 and left- 57) were selected through the purposive sampling technique for this cross-sectional descriptive study carried out in the Department of Anatomy, Mymensingh Medical College, Bangladesh from July 2021 to June 2022. Any damaged, unossified bones or fractured bones were excluded. Data were tabulated and statistically analyzed using Microsoft Excel and SPSS software. Among 43 right humeri, 37(75.51%) have single-nutrient foramen and 06(24.49%) have double-nutrient foramina. Among 57 left humeri, 53(92.98%) have single nutrient foramen, 03(5.27%) have double nutrient foramina and 01(1.75%) has triple nutrient foramina. In case of location of nutrient foramina, among 49 right nutrient foramina, 45(91.84%) were found on the anteromedial surface, 02(4.08%) were found on the anterolateral surface and 02(4.08%) were on the posterior surface of the shaft of the humerus. In case of 62 left nutrient foramina, 57(91.94%) were found on the anteromedial surface and 05(8.06%) were found on the posterior surface of the shaft of the humerus. Among 49 right nutrient foramina, 01(2.04%) was found on the upper third, 46(93.88%) on the middle third and 02(4.08%) on the lower third of the shaft of the humerus. In case of 62 left nutrient foramina, 01(1.60%) was on the upper third, 57(91.95%) were on the middle third and 04(6.45%) were on the lower third of the shaft of the humerus.

Role of Vitamin B12 Deficiency and Hyperhomocysteinemia in Diabetic Retinopathy.

Diabetic retinopathy (DR) is one of the most important causes of preventable visual impairment among patients of working age and leading cause of blindness. Deficiency of vitamin B12 and folate has been associated with increased serum homocysteine (Hcy) levels. This study was done to find out the role of vitamin B12 and Hyperhomocysteine (HHcy) in Diabetic retinopathy. The present study is a hospital-based case-control study conducted during over a period of 12 months from January 2019 to December 2019 study conducted in the Department of Ophthalmology at BIRDEM General Hospital, Dhaka, Bangladesh consisting of 100 Type 2 DM patients either with or without retinopathy (DR, n=50 and DNR, n=50, respectively). Subjects with Type 2 DM with and without retinopathy were recruited from patients attending in the department of Ophthalmology at BIRDEM General Hospital, Dhaka and were matched for duration of diabetes. Diabetes subjects on nutritional supplements for the last 6 months and those with a history of nephropathy (based standard renal function tests) and complications other than DR were excluded. Homocysteine (Hcy) levels were inversely related (p<0.05) with Diabetes patients with retinopathy. Vitamin B12 also significant correlated with Diabetes patients with retinopathy. A statistically significant negative linear relationship was found between serum homocysteine and vitamin B12 levels (Pearson r = -0.918, p=0.001) Diabetes patients with retinopathy. Vitamin B12 significantly correlated with diabetes retinopathy and homocysteine levels were inversely related with diabetes patients with retinopathy.

Socio-demographic Profile of COVID-19 Patients and Difficulties Faced by Them while Testing RT-PCR: A Multi-center Cross-sectional Study.

This study was aimed to find out the socio-demographic profiles as well as difficulties of Reverse transcription polymerase chain reaction (RT-PCR) testing faced by Coronavirus Disease 2019 (COVID-19) patients. This cross-sectional study was conducted from 10th August to 7th September 2020. Data were collected by telephone interview using a pre-designed questionnaire after taking verbal consent from the participants. Out of 281 COVID-19 patients, 279 were diagnosed by RT-PCR; 10.3% were asymptomatic. Off them 67.6%were males, 24% were hospital staffs. Majority (66.2%) were from the non-city corporation area. History of recent contact with known COVID-19 patients was present in 56.9% cases. Fever (78.3%) and cough (58%) were the most common symptoms. One third of the patients faced difficulty to test RT-PCR for COVID-19. Sixteen percent patients complained of difficulty of getting serial for testing, the maximum waiting time was one week before giving samples. Thirty patients (10.8%) had to wait longer than usual time after reaching the center before giving sample. Hospital staffs were unable to co-operate in 2.5% of the patients while difficulty of managing transport to the hospital for suspected COVID-19 patient was an issue in 2.2% of the patients. Though testing was more difficult in city corporation areas (p=0.028), delay of getting test result was less (p<0.001). Maximum delay of getting test result was 10 days. Finding out the difficulties of COVID-19 testing will help to point out the issues behind these and will help to take necessary steps to tackle this matter. Testing rate can be increased to contain this highly contagious virus in this densely populated country.

Risk of Abdominal Aortic Calcifications among End Stage Renal Disease Patients under Maintenance Haemodialysis.

Calcification of soft tissue and blood vessel wall occurs more frequently in dialyzed patients. The purpose of the present study was to estimate the risk of abdominal aortic calcification among end stage renal disease patients under maintenance haemodialysis. This case-control study was carried out in the Department of Nephrology at National Institute of Kidney Diseases and Urology (NIKDU), Dhaka and National Institute of Cardiovascular Disease and Hospital (NICVD), Dhaka, Bangladesh from January 2013 to December 2014 for a period of two (02) years. Chronic kidney disease in stage 5 {CKD-5(D)} patients older than 18 years on maintenance haemodialysis (MHD) for more than 3 months were selected as case group. And same age and sex non CKD patients were considered as control group. Serum calcium, serum albumin, serum phosphate and iPTH were estimated by semi-automated biochemistry analyzer from the Department of Biochemistry of NIKDU, Dhaka and NICVD, Dhaka. Plain X-ray abdomen in lateral view was performed for all patients. Total 100 patients were enrolled for this study of which 50 patients were in end stage renal disease (ESRD) group and the rest 50 patients were in non-CKD group. Abdominal aortic calcification on X ray was present in 22(44%) patients of ESRD group and 6(12%) patients of non CKD group of population. Mean±SD serum calcium (corrected) level was significantly high (p<0.001) in ESRD patients (9.79±0.87) compared to non CKD group of population (9.13±0.70). Mean±SD of serum phosphate level was significantly higher (p<0.001) in ESRD patients (5.71±0.96) compared to non CKD group of population (4.20±0.59). However, mean±SD iPTH level showed no significant difference between ESRD (25.33±51.98) and non CKD group of population (38.53±19.52), though iPTH level remain below the target level in ESRD group. Abdominal aortic calcification is significantly higher among ESRD subjects.

Are we missing diagnostic opportunities in cases of carcinoid tumours of the appendix?

OBJECTIVE: Carcinoid tumour of appendix is an uncommon condition that can potentially give rise to a variation in management. We aimed to assess the occurrence and mode of presentation of carcinoid tumour of appendix, and any variation of its management. METHODS: All appendicectomies that took place at North Middlesex University Hospital, London between 1995 and 2005 were considered for study. RESULTS: A total of 1941 appendicectomies took place. Sixteen (0.82%) patients had carcinoid tumours. The mean age of patients with carcinoid tumour (41.8 years) was significantly higher than those with non-carcinoid pathology (27.7 years) (p = 0.001). The incidence of female patients was higher than the male amongst the carcinoid tumour group (female/male ratio 2.2). None of the carcinoid tumours were identified at operation. Eight patients as well as their general practitioners (53.3%) were unaware of the diagnosis. Multidisciplinary team involvement or specialty referral took place in three cases (20%). One patient (6.6%) required right hemicolectomy. Three patients (20%) were followed-up in inconsistent manner. CONCLUSIONS: Carcinoid tumour of the appendix remains an incidental diagnosis. Patients with carcinoids were significantly older than non-carcinoid conditions. There was a trend of increased occurrence of carcinoids amongst the females. Re-operation rate was low. There was a wide variation in involving the multidisciplinary team, conveying the diagnosis to patients as well as their general practitioners, and follow-ups. This can be perceived as a missed opportunity of selective screening of synchronous and metachronous lesions, raises clinical governance issues and has medicolegal implications.

Haemato-biochemical responses and induction of HSP70 to dietary phosphorus in Catla catla (Hamilton) fingerlings.

A feeding trial of 120 days was conducted to study the effect of graded levels of dietary phosphorus on haematology, serum protein concentrations and HSP70 expression in fingerlings of the Indian major carp, Catla (Catla catla). Eight isonitrogenous and isoenergetic purified diets were formulated to contain graded levels of dietary phosphorus (dP), i.e., T(1), 0.1%; T(2), 0.3%; T(3), 0.5%; T(4), 0.7%; T(5), 0.9%; T(6), 1.1%; T(7), 1.3%; or T(8), 1.5%. Four hundred and eighty fish (average weight 4.23 +/- 0.016 g) were equally distributed into 24 tanks forming eight treatments with three replicates each. The fish were fed daily at the rate of 3.5% body weight in two instalments. At the end of feeding trial fish were sampled to study total RBC and WBC count, haemoglobin, serum lysozyme activity, serum total protein, albumin (A), globulin (G) concentration and HSP70 expression. Total RBC count, haemoglobin concentration and serum lysozyme activity did not vary significantly in response to different dietary phosphorus concentrations. Total WBC count was found to be significantly (P < 0.05) higher in T(1 )relative to all other treatments. Serum albumin and A/G ratio was found to be significantly lower in fish of T(1) and T(2) in relation to T(7) group (P < 0.05). Serum globulin and total protein levels remained unaffected by variations in dietary phosphorus. HSP70 expression was observed in T(1) group (0.1% dP) in gills and brain tissue, but not in liver and muscle tissues. No HSP70 expression was observed in fish of T(4) (0.7% dP) and T(8) (1.5% dP) treatments. These prima facie results suggest that dietary phosphorus had only minor influence on the haemato-biochemical parameters studied; however dietary phosphorus deficiency caused organ specific induction of HSP70 in catla fingerlings.

Digestive enzymes and metabolic profile of Labeo rohita fingerlings fed diets with different crude protein levels.

Labeo rohita, commonly called rohu is one of the most important fish species for aquaculture in India. Digestive enzyme response and metabolic profile of fingerling L. rohita to different dietary crude protein (CP) levels (viz. 25, 30, 35 and 40%) were studied in an attempt to optimize a practical diet formulation for this species. After 45 days of feeding, activity of digestive enzymes and metabolite concentrations were assayed. Amylase, lipase and alkaline phosphatase (ALP) activities were not influenced by the dietary protein, but proteolytic and acid phosphatase (ACP) activities varied (P<0.05) between the treatments. Proteolytic activity showed a second order polynomial relationship with dietary crude protein (CP) as Y = 0.0734X(2) + 4.937X - 68.37, r(2)=0.97. A positive correlation was observed between dietary CP and amylase (r(2)=0.78). All the metabolites except muscle glucose showed significant change corresponding to the dietary protein levels. Glucose and glycogen levels corresponded to the dietary carbohydrate levels. Muscle and plasma pyruvic acid increased as the crude protein in the diet increased, whereas liver pyruvic acid showed the opposite trend. Muscle protein content was not affected by dietary CP. Protein fractions in plasma (total protein, albumin and globulin) showed maximum values in 30% CP fed group. It is concluded that proteolytic activity and ACP are the major digestive enzymes responsive to dietary CP in L. rohita fingerlings. Considering the cost effectiveness of the diet, and based on liver and plasma free amino acid levels and plasma protein fractions, 30% crude protein is recommended as the optimal dietary protein for L. rohita fingerlings.

Interactions of berberine with poly(A) and tRNA.

The interaction of berberine chloride with poly(A) and tRNA has been studied by various spectroscopic techniques. Binding parameters determined from spectrophotometric and spectrofluorimetric measurements by Scatchard analysis indicate a very high effective binding capacity of berberine to poly(A) as compared to DNA or tRNA. The circular dichroism studies show that binding of berberine to poly(A) causes a significant change in the circular dichroic spectrum of poly(A) itself, as manifested by (i) a decrease of both positive and negative bands and (ii) appearance of a conservative type of extrinsic circular dichroic spectrum in the wavelength range of 300-400 nm, while it does not cause any significant alteration to the A form structure of tRNA. It is concluded that berberine interacts stronger with poly(A) than DNA or tRNA. The results are interpreted in terms of its reported biological activities.

Thermodynamics of the interaction of berberine with DNA.

The interaction of berberine [7,8,13,13a-tetrahydro-9-10-dimethoxy-2,3-(methylene dioxy)-berberinium] with calf thymus DNA has been studied by spectrophotometry in buffers of various salt concentrations and temperatures. Binding parameters obtained are best fit by the neighbour exclusion model. The salt and temperature dependence of the binding constants are used to estimate thermodynamic parameters involved in the complex formation of berberine with DNA. The binding process is exothermic over the entire range and the values of enthalpy and entropy change are strongly dependent on the salt concentration. The negative enthalpy and positive entropy changes compensate one another to produce a relatively small Gibbs' free energy change. Possible molecular contribution to the enthalpy and entropy changes is discussed.

Circular dichroism studies of the structure of DNA complex with berberine.

The binding of the benzodioxolo-benzoquinolizine alkaloid, berberine chloride to natural and synthetic DNAs has been studied by intrinsic and extrinsic circular dichroic measurements. Binding of berberine causes changes in the circular dichroism spectrum of DNA as shown by the increase of molar ellipticity of the 270nm band, but with very little change of the 240nm band. The molar ellipticity at the saturation depends strongly on the base composition of DNA and also on salt concentration, but always larger for the AT rich DNA than the GC rich DNA. The features in the circular dichroic spectral changes of berberine-synthetic DNA complexes were similar to that of native DNA, but depends on the sequence of base pairs. On binding to DNA and polynucleotides, the alkaloid becomes optically active. The extrinsic circular dichroism developed in the visible absorption region (300-500nm) for the berberine-DNA complexes shows two broad spectral bands in the regions 425-440nm and 340-360nm with the maximum varying depending on base composition and sequence of DNA. While the 425nm band shows less variation on the binding ratio, the 360nm band is remarkably dependent on the DNA/alkaloid ratio. The generation of the alkaloid associated extrinsic circular dichroic bands is not dependent on the base composition or sequence of base pairs, but the nature and magnitude of the bands are very much dependent on these two factors and also on the salt concentration. The interpretation of the results with respect to the modes of the alkaloid binding to DNA are presented.

Effect of hydrocortisone on the hemodynamics and serum CK and MBCK enzymes in acute myocardial infarct in dogs.

The effects of hydrocortisone on the hemodynamics and plasma creatine kinase (CK) in dogs with acute myocardial infarction were investigated. Acute myocardial infarction was produced by ligating the anterior descending branch of the left coronary artery and the effects on hemodynamics and plasma CK were observed for two hours. Complete coronary ligation produced a decrease in the cardiac index and left ventricular work index following two hours of coronary ligation. Other hemodynamic parameters (systemic and pulmonary arterial pressure, left ventricular pressure, right atrial pressure, pulmonary arterial wedge pressure, systemic and pulmonary vascular resistance, heart rate, cardiac effort) were essentially unaffected. There was a tendency for an increase in (dp/dt)/IIP but the increase was not significant. In hydrocortisone treated dogs, all the hemodynamic parameters were unaffected except the cardiac index which decreased significantly. Partial coronary ligation produced an increase in the systemic and pulmonary vascular resistance and a decrease in the cardiac index. The other hemodynamic parameters were unaffected. Plasma CK and MBCK increased significantly in dogs with partial or complete ligation of coronary artery. The serum CK was more in partially ligated than in complete coronary ligated dogs. Although hydrocortisone pretreatment decreased the rise of plasma CK it did not change the rise in MBCK observed in coronary ligated dogs without hydrocortisone treatment. These results indicate that hydrocortisone prevents, although not completely, the deleterious effects of ischemia on the plasma CK but has no effect on the increase in plasma MBCK and decrease in the cardiac index.

Structural perturbation of proteins in low denaturant concentrations.

The presence of very low concentrations of the widely used chemical denaturants, guanidinium chloride and urea, induce changes in the tertiary structure of proteins. We have presented results on such changes in four structurally unrelated proteins to show that such structural perturbations are common irrespective of their origin. Data representative of such structural changes are shown for the monomeric globular proteins such as horseradish peroxidase (HRP) from a plant, human serum albumin (HSA) and prothrombin from ovine blood serum, and for the membrane-associated, worm-like elongated protein, spectrin, from ovine erythrocytes. Structural alterations in these proteins were reflected in quenching studies of tryptophan fluorescence using the widely used quencher acrylamide. Stern-Volmer quenching constants measured in presence of the denaturants, even at concentrations below 100 mM, were higher than those measured in absence of the denaturants. Both steady-state and time-resolved fluorescence emission properties of tryptophan and of the extrinsic probe PRODAN were used for monitoring conformational changes in the proteins in presence of different low concentrations of the denaturants. These results are consistent with earlier studies from our laboratory indicating structural perturbations in proteins at the tertiary level, keeping their native-like secondary structure and their biological activity more or less intact.

Interaction of the antitumour alkaloid coralyne with duplex deoxyribonucleic acid structures: spectroscopic and viscometric studies.

The interaction of coralyne, an antitumour alkaloid with natural and synthetic duplex DNAs was investigated under conditions where the drug existed fully as a true monomer for the first time using spectrophotometric, spectrofluorimetric, circular dichroic and viscometric techniques. The absorption spectrum of coralyne monomer showed hypochromic and bathochromic effects on binding to duplex DNAs. This effect was used to determine the binding parameters of coralyne. The binding constants for four natural DNAs and four synthetic polynucleotides obtained from spectrophotometric titration, according to an excluded site model, using McGhee-von Hippel analysis, were all in the range of (0.38-9.8) x 10(5) M-1, and showed a relatively high specificity for the GC rich ML DNA and the alternating GC polynucleotide. The binding of coralyne decreased with increasing ionic strength, indicating that the binding affinity has a strong electrostatic component. Coralyne stabilized all the DNAs against thermal strand separation. The intense steady state fluorescence of coralyne was effectively quenched on binding to DNAs and the quantitative data on the Stern-Volmer quenching constant obtained was sequence dependent, being maximum with the GC rich DNA and alternating GC polymer. Circular dichriosm studies further evidenced for a strong perturbation of the B-conformation of DNAs consequent to coralyne binding with the concomitant development of extrinsic circular dichroic bands for the bound drug molecules suggesting their strong intercalated geometry in duplex DNAs. Further tests of intercalation using viscosity measurements on linear and covalently closed plasmid DNA conclusively proved the strong intercalation of coralyne in duplex DNA. Binding of the closely related natural alkaloid, berberine under these conditions showed considerably lower affinity to duplex DNAs in all experiments. Taken together, these results suggest that coralyne binds strongly to duplex DNAs by a mechanism of intercalation with specificity towards alternating GC duplex structure.

Interaction of berberine chloride with deoxyribonucleic acids: evidence for base and sequence specificity.

The interaction of berberine chloride with natural and synthetic DNAs of differing base composition and sequences was followed by various spectroscopic and viscometric studies. The binding of berberine chloride was characterized by hypochromism and bathochromism in the absorption bands, enhancement of fluorescence intensity, stabilization against thermal denaturation, perturbations in the circular dichroic spectrum, increase in the contour length of sonicated rod-like DNA and induction of unwinding-rewinding process of covalently closed superhelical DNA, depending on the base composition and sequences of base pairs. Binding parameters determined from absorbance and fluorescence titration by Scatchard analysis, according to an excluded-site model, indicated a very high specificity of berberine to AT-rich DNAs and alternate AT polymer. Fluorescence quantum yield was maximum for the complexes with AT-rich DNAs and alternate AT polymer. Taken together, these results suggest that berberine chloride exhibits considerable specificity towards alternating AT polymer and binds to AT-rich DNAs by a mechanism of classical intercalation.

Improving reporting of sharp injuries.

There is considerable under-reporting of contaminated needlestick and other sharp object injuries among health-care workers. Some general and psychological factors contribute to such low reporting. Continued training of staff, a sympathetic attitude and clarification of some general issues might improve reporting of such incidents.

Use of antibiotic prophylaxis in elective inguinal hernia repair in adults in London and south-east England: a cross-sectional survey.

PURPOSE: Evidence regarding whether or not antibiotic prophylaxis is beneficial in preventing post-operative surgical site infection in adult inguinal hernia repair is conflicting. A recent Cochrane review based on 17 randomised trials did not reach a conclusion on this subject. This study aimed to describe the current practice and determine whether clinical equipoise is prevalent. METHODS: Surgeons in training were recruited to administer the Survey of Hernia Antibiotic Prophylaxis usE survey to consultant-level general surgeons in London and the south-east of England on their practices and beliefs regarding antibiotic prophylaxis in adult elective inguinal hernia repair. Local prophylaxis guidelines for the participating hospital sites were also determined. RESULTS: The study was conducted at 34 different sites and received completed surveys from 229 out of a possible 245 surgeons, a 93 % response rate. Overall, a large majority of hospital guidelines (22/28) and surgeons' personal beliefs (192/229, 84 %) supported the use of single-dose pre-operative intravenous antibiotic prophylaxis in inguinal hernia repair, although there was considerable variation in the regimens in use. The most widely used regimen was intravenous co-amoxiclav (1.2 g). Less than half of surgeons were adherent to their own hospital antibiotic guidelines for this procedure, although many incorrectly believed that they were following these. CONCLUSION: In the south-east of England, there is a strong majority of surgical opinion in favour of the use of antibiotic prophylaxis in this procedure. It is therefore likely to be extremely difficult to conduct further randomised studies in the UK to support or refute the effectiveness of prophylaxis in this commonly performed procedure.

In vitro association of fragments of a beta-sheet membrane protein.

Although the beta-barrel membrane protein OmpA can be produced in a biologically active form in E. coli from co-expressed fragments, the fragments have not been demonstrated to associate in vitro. We have produced 3 complementary fragment pairs of OmpA which can associate to form a folded complex according to the SDS band-shift assay. We are able to convert 25-35% of the fragment populations to non-covalent but SDS-stable complexes. The periplasmic chaperone Skp effectively prevented this association. Two separately expressed and purified overlapping fragments of OmpA can form a protease-resistant complex that undergoes the characteristic band-shift upon heating. Our work demonstrates that although membrane insertion and folding of beta-barrel membrane proteins may be a cooperative process, the fragments can associate in vitro without any additional components. However, the low yield and slow folding rates indicate that partially unfolded or destabilized beta-sheet membrane proteins can potentially engage in many non-native interactions.