Clinical efficacy of buprenorphine after oral dosing in rats undergoing major surgery.

Serum corticosterone, serum buprenorphine, body weight change, consumption of food and water and behaviour-based pain assessment were measured in catheterised and non-catheterised male Wistar rats undergoing myocardial infarct (MI) surgery under general anaesthesia following buprenorphine dosing by subcutaneous (Bup-SC, 0.05 mg/kg) and oral (Bup-O, 0.4 mg/kg) routes. Buprenorphine was dosed subcutaneously at half an hour before and 8, 16 and 24 hours after surgery (Bup-SC), orally at one hour before surgery (Bup-O1) or at one hour before and 12 hours after surgery (Bup-O2) in catheterised rats and at one hour before and 24 hours after surgery (Bup-O24) in non-catheterised rats. Serum corticosterone, body weight changes and food and water consumption were not significantly different between treatments in catheterised rats. Bup-SC resulted in rapidly decreasing serum concentrations below the clinically effective concentrations (1 ng/mL) already at two hours after the first dose. Bup-O provided significantly higher and slowly decreasing serum concentrations, at or above clinically effective concentrations, for 24 hours (Bup-O1) and 42 hours (Bup-O2) after surgery. In non-catheterised rats, body weight development and food consumption were significantly higher in Bup-O24 rats compared to Bup-SC rats. The results indicate that a SC buprenorphine dose of 0.05 mg/kg every eight hours provides long periods of serum concentrations below clinically effective levels, and that a higher dose and/or more frequent dosage are required to provide stable serum concentrations at or above clinically effective levels. A single oral buprenorphine dose of 0.4 mg/kg provides clinically effective and stable serum concentrations for 24 hours in rats after MI surgery.

Factors Predictive of Tenotomy After Ponseti Casting for Idiopathic Clubfoot: A Tertiary Care Center Study.

INTRODUCTION: Parents of children with clubfoot are likely to inquire about the need for tenotomy and about any factors that may be predictive. The present study was done to identify factors that may help predict the need for tenotomy in children undergoing Ponseti treatment for idiopathic clubfoot. METHODS: A prospective observational study was conducted on patients under 5 years of age with idiopathic clubfoot and no previous treatment history treated at Hospital and Rehabilitation Centre for Disabled Children. The relationship between the Pirani score, Dimeglio score, age, and passive ankle dorsiflexion (DF) and the need for heel cord tenotomy was analyzed using appropriate statistical methods. RESULTS: Of 83 patients (125 feet) with a mean age of 6 months, 93 feet (74.4%) required a percutaneous tenotomy. The mean initial Pirani and Dimeglio score for 125 club feet was 4.5 (SD=1.68) and 13.5 (SD=6.1), respectively. The mean initial passive ankle DF was -40.4 (SD=22.31). The Dimeglio ( P =0.000), Pirani scores ( P =0 .000), and passive ankle DF ( P =0.000) showed significant association with the need for tenotomy. CONCLUSIONS: This study shows a strong association between initial Pirani and Demiglio scores and initial passive ankle DF as predictive of a heel cord tenotomy. However, age, sex, and laterality were not associated with the need for tenotomy.

Farm characteristics and sero-prevalence of porcine reproductive and respiratory syndrome virus (PRRSV) antibodies in pigs of Nepal.

BACKGROUND: Porcine reproductive and respiratory syndrome is a highly infectious disease of swine caused by PRRS virus (PRRSV). OBJECTIVES: To evaluate the prevalence of PRRSV antibodies in the four districts of hilly and terai regions of Nepal. Toassess the farm characteristics through a questionnaire interview of farmersregarding management practices and PRRS. METHODS: A cross-sectional study was conducted from July 2020 to June 2021 to determine the sero-prevalence of PRRSV in pigs. A total of 180 porcine serum samples were collected from 23 pig farms and tested for PRRSV antibodies by ELISA. Alongside, farm characteristics were also assessed through questionnaire to determine the level of biosecurity measures in the farm, knowledge of the disease and possible control mechanisms. RESULTS: Out of 180 samples, 37 were tested positive resulting the overall sero-prevalence of 20.5%. There was significant association between different districts (p < 0.05) and PRRS prevalence. Prevalence of PRRSV antibody was found higher in Kaski district (10.5%) followed by Sunsari (8.8%) district. Based on age groups, highest prevalence was found in age groups of above 18 months (9.4%), followed by 13-18 months age groups (7.7%). Regarding the knowledge level of the disease, 43% of the farmers responded that they have heard about the disease. Biosecurity practices in the farm was found very poor where only 40% of the farms had disinfectant at the entrance of the farm and 25% pig farmers were found using separate boots while dealing with pigs. CONCLUSIONS: The findings of this study reveal the presence of PRRSV antibodies in pigs of Nepal. In addition poor biosecurity measures, management practices and poor knowledge level about the disease among farmers highly affect in the control and prevention of disease thereby affecting the pig production and productivity. Therefore, government should develop and implement effective control measures and biosecurity programs.

Cerebral Palsy among Children Visiting the Outpatient Department of Pediatric Orthopaedics in a Tertiary Care Centre.

Introduction: Cerebral palsy is a group of neurological disorders that appear in infancy or early childhood and occur as a result of anomalies in the developing brain that impair the brain's capacity to regulate movement, maintain posture, and maintain balance. Healthcare professionals can better predict the need for the medical, rehabilitative, and support services needed by people with cerebral palsy by using accurate prevalence statistics. The aim of the study was to find out the prevalence of cerebral palsy among children visiting the Outpatient Department of Pediatric Orthopaedics in a tertiary care centre. Methods: A descriptive cross-sectional study was conducted among patients visiting the Outpatient Department of Pediatric Orthopaedics in a tertiary care centre. Data from 1 January 2018 to 31 December 2019 was collected between 25 April 2023 to 5 May 2023 from medical records after obtaining ethical approval from the Institutional Review Committee. Convenience sampling method was used. The point estimate was calculated at a 95% Confidence Interval. Results: Among 6984 children, the prevalence of cerebral palsy was 545 (7.80%) (7.17-8.43, 95% Confidence Interval). The most common type of cerebral palsy was found to be spastic diplegia 219 (40.18%). Conclusions: The prevalence of cerebral palsy among children visiting the Outpatient Department of Pediatric Orthopaedic was found to be higher than in other studies done in similar settings. Keywords: cerebral palsy; prevalence; spastic diplegia.

Hip arthrodesis in children : a review of 26 cases with a mean of 20 years' follow-up.

AIMS: To examine the long-term outcome of arthrodesis of the hip undertaken in a paediatric population in treating painful arthritis of the hip. In our patient population, most of whom live rurally in hilly terrain and have limited healthcare access and resources, hip arthrodesis has been an important surgical option for the monoarticular painful hip in a child. METHODS: A follow-up investigation was undertaken on a cohort of 28 children previously reported at a mean of 4.8 years. The present study looked at 26 patients who had an arthrodesis of the hip as a child at a mean follow-up of 20 years (15 to 29). RESULTS: The mean Harris Hip Score (HHS) increased from 39.60 (SD 11.06) preoperatively to 81.02 (SD 8.86; p = 0.041) at final review. At latest follow-up, the HHS was found to be excellent in four patients (15%), good in 11 (42%), and fair in 11 (42%). A total of 16 patients (62%) reported mild low back pain, five (19%) had moderate pain, and five (19%) patients had no back pain. Mild ipsilateral knee pain was reported by 19 (73%), moderate pain by one (4%), and no pain by six (23%) patients. Mild contralateral hip pain was reported by ten patients (38%), and no pain by 16 (62%). The 36-Item Short Form Health Survey scores were very good in four patients (15%), good in 18 (70%), and poor in four (15%), with a mean score of 70.92 (SD 12.65). Of 13 female patients who had given birth, 12 did so with uncomplicated vaginal delivery. All patients had to modify their posture for toileting, putting on lower body clothes, foot care, and putting on shoes. CONCLUSION: Our results show that with hip arthrodesis, most patients have relatively good function at long-term follow-up, although some pain is experienced in adjacent joints, and modification in some activities of daily living is common.Cite this article: Bone Joint J 2022;104-B(9):1089-1094.

Outcomes of the Ponseti Method for Untreated Clubfeet in Nepalese Patients Seen Between the Ages of One and Five Years and Followed for at Least 10 Years.

BACKGROUND: To our knowledge, there are no reports of the Ponseti method initiated after walking age and with >10 years of follow-up. Our goal was to report the clinical findings and patient-reported outcomes for children with a previously untreated idiopathic clubfoot who were seen when they were between 1 and 5 years old, were treated with the Ponseti method, and had a minimum follow-up of 10 years. METHODS: A retrospective review of medical records was supplemented by a follow-up evaluation of physical findings (alignment and range of motion) and patient-reported outcomes using the Oxford Ankle Foot Questionnaire for Children (OxAFQ-C). The initial treatment was graded as successful if a plantigrade foot was achieved without the need for an extensive soft-tissue release and/or osseous procedure. RESULTS: We located 145 (91%) of 159 patients (220 clubfeet). The average age at treatment was 3 years (range, 1 to 5 years), and the average duration of follow-up was 11 years (range, 10 to 12 years). The initial scores according to the systems of Pirani et al. and Diméglio et al. averaged 5 and 17, respectively, and an average of 8 casts were required. Surgical treatment, most commonly a percutaneous Achilles tendon release (197 feet; 90%), was required in 96% of the feet. A plantigrade foot was achieved in 95% of the feet. Complete relapse was rare (3%), although residual deformities were common. Patient-reported outcomes were favorable. CONCLUSIONS: A plantigrade foot was achieved in 95% of the feet initially and was maintained in most of the patients, although residual deformities were common. Patient-reported outcomes were satisfactory, and longer-term follow-up with age-appropriate outcome measures will be required to evaluate function in adulthood. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Modulation of Lung Function by Increased Nitric Oxide Production.

INTRODUCTION: Cigarette smoking reduces endogenous Nitric Oxide (NO) production by reducing Nitric Oxide Synthase (NOS) activity, which is one of the probable reason for increased rate of pulmonary diseases in smokers. Nitric oxide/oxygen blends are used in critical care to promote capillary and pulmonary dilation to treat several pulmonary vascular diseases. Among several supplements, the highest NOS activation has been proved for garlic with its unique mechanism of action. AIM: To investigate the effect of dietary supplementation of NO producing garlic on pulmonary function of smokers. MATERIALS AND METHODS: The study was conducted on 40 healthy non-smoker (Group A) and 40 chronic smoker (Group B) males with matched age, height and weight. The pulmonary function tests- Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1), FEV1/FVC ratio and Peak Expiratory Flow Rate (PEFR) were performed in non-smokers (Group A), smokers (Group B) and smokers after supplementation of approximately 4 gm of raw garlic (2 garlic cloves) per day for three months (Group C). Endogenous NO production was studied in smokers before and after garlic supplementation and in non-smokers without supplementation. The data obtained were compared between the groups using unpaired student's t-test. The p-value considered significant at <0.05. RESULTS: Our results showed that FVC, FEV1, FEV1/FVC ratio and PEFR were reduced significantly along with a significant decreased NOS activity among smokers (Group B) when compared with non-smokers (Group A). Garlic supplementation significantly improved the pulmonary function tests in Group C in comparison to Group B by increasing NOS activity. CONCLUSION: Dietary supplementation of garlic, which might be by increasing NOS activity, has significantly improved pulmonary functions in smokers.

Nerve Conduction Study on Sural Nerve among Nepalese Tailors Using Mechanical Sewing Machine.

INTRODUCTION: The use of new technologies and innovations are out of access for people living in a developing country like Nepal. The mechanical sewing machine is still in existence at a large scale and dominant all over the country. Tailoring is one of the major occupations adopted by skilled people with lower socioeconomic status and education level. Sural nerves of both right and left legs are exposed to strenuous and chronic stress exerted by chronic paddling of mechanical sewing machine with legs. AIM: To evaluate the influence of chronic and strenuous paddling on right and left sural nerves. MATERIALS AND METHODS: The study recruited 30 healthy male tailors with median age {34(31-37.25)} years (study group), and, 30 healthy male volunteers with age {34(32-36.25)} years (control group). Anthropometric measurements (age, height, weight, BMI and length of both right and left legs) as well as cardio respiratory measurements [Systolic Blood Pressure (SBP), Dystolic Blood Pressure (DBP), Pules Rate (PR) and Respiratory Rate (RR)] were recorded for each subject. Standard nerve conduction techniques using constant measured distances were applied to evaluate sural nerve (sensory) in both legs of each individual. The differences in variables between the study and control groups were tested using Student's t-test for parametric variables and Mann-Whitney U test for nonparametric variables. A p-value of ≤ 0.05 was considered significant. RESULTS: Age, height, weight, body mass index and leg length were not significantly different between tailors and control groups. Cardio respiratory measurements (SBP, DBP, PR and RR) were also not significantly altered between both the groups. The sensory nerve conduction velocities (m/s) of the right {44.23(42.72-47.83) vs 50(46- 54)} and left sural nerves {45.97±5.86 vs 50.67±6.59} m/s were found significantly reduced in tailors in comparison to control group. Similarly amplitudes (µv) of right sural (20.75±5.42 vs 24.10±5.45) and left sural nerves {18.2(12.43-21.8) vs 32.0(26.5-35.25)} were significantly less in tailors in comparison to control group whereas, latencies (ms) of right sural {2.6(2.2-2.7) vs 2.0(2.0-2.250} and left sural nerve {2.4(2.07-2.72) vs 2.0(2.0-2.0)} were found significantly high in tailors as compared with control group. CONCLUSION: Operating mechanical sewing machine by paddling chronically and arduously could have attributed to abnormal nerve conduction study parameters due to vibration effect of the machine on right and left sural nerves. The results of present study follow the trend towards presymptomatic or asymptomatic neuropathy similar to subclinical neuropathy.

Association between obesity and heart rate variability indices: an intuition toward cardiac autonomic alteration - a risk of CVD.

BACKGROUND: Obese people have a higher prevalence of cardiovascular disease, which is supposed to be due to autonomic dysfunction and/or metabolic disorder. The alterations in cardiac autonomic functions bring out the changes in the heart rate variability (HRV) indicators, an assessing tool for cardiac autonomic conditions. OBJECTIVE: To compare the cardiac autonomic activity between obese and normal weight adults and find out the highest association between the indices of HRV and obesity. METHODS: The study was conducted in 30 adult obese persons (body mass index [BMI] >30 kg/m2) and 29 healthy normal weight controls (BMI 18-24 kg/m2). Short-term HRV variables were assessed using standard protocol. Data were compared between groups using Mann-Whitney U test. Obesity indices such as waist circumference, hip circumference, waist-hip ratio (WHR), and BMI were measured and calculated, and they were correlated with HRV indices using Spearman's correlation analysis. RESULTS: In the obese group, there was a significant increase in the mean heart rate, whereas the HRV parasympathetic indicators were less (eg, root mean square of differences of successive RR intervals [28.75 {16.72-38.35} vs 41.55 {30.6-56.75} ms, p=0.018], number of RR intervals that differ by >50 ms, that is, NN50 [15.5 {2-39} vs 83.5 {32.75-116.25}, p=0.010], etc) and the sympathetic indicator low frequency (LF)/high frequency (HF) ratio (1.2 [0.65-2.20] vs 0.79 [0.5-1.02], p=0.045) was more than that of the normal weight group. Spearman's correlation between HRV and obesity indices showed significant positive correlation of WHR with LF in normalized unit (r=0.478, p<0.01) and LF/HF ratio (r=0.479, p<0.01), whereas it had significant negative correlation with high frequency power ms2 (r=-0.374, p<0.05) and HF in normalized unit (r=-0.478, p<0.01). There was a nonsignificant correlation of BMI with HRV variables in obese individuals. CONCLUSION: Increased WHR, by far an indicator of visceral adiposity, was strongly associated with reduced cardiac parasympathetic and increased sympathetic activity in obese individuals defined by BMI. However, BMI itself has a weak relationship with HRV cardiac autonomic markers. Thus, even with a slight increase in WHR in an individual, there could be a greater risk of cardiovascular morbidity and mortality brought about by cardiac autonomic alterations.

Vibration upshot of operating mechanical sewing machine: an insight into common peroneal nerve conduction study.

BACKGROUND: Most of the people associated with tailoring occupation in Nepal are still using mechanical sewing machine as an alternative of new technology for tailoring. Common peroneal nerves of both right and left legs are exposed to strenuous and chronic stress exerted by vibration and paddling of mechanical sewing machine. METHODS: The study included 30 healthy male tailors and 30 healthy male individuals. Anthropometric variables as well as cardio respiratory variables were determined for each subject. Standard Nerve Conduction Techniques using constant measured distances were applied to evaluate common peroneal nerve (motor) in both legs of each individual. Data were analyzed and compared between study and control groups using Man Whitney U test setting the significance level p ≤ 0.05. RESULTS: Anthropometric and cardio respiratory variables were not significantly altered between the study and control groups. The Compound muscle action potential (CMAP) latency of common peroneal nerves of both right [(11.29 ± 1.25 vs. 10.03 ± 1.37), P < 0.001] and left [(11.28 ± 1.38 vs. 10.05 ± 1.37), P < 0.01] legs was found to be significantly prolonged in study group as compared to control group. The Amp-CMAP of common peroneal nerves of both right [(4.57 ± 1.21 vs. 6.22 ± 1.72), P < 0.001] and left [(4.31 ± 1.55 vs. 6.25 ± 1.70), P < 0.001] legs was found significantly reduced in study group as compared to control group. Similarly, the motor nerve conduction velocity (MNCV) of common peroneal nerves of both right [(43.72 ± 3.25 vs. 47.49 ± 4.17), P < 0.001] and left [(42.51 ± 3.82 vs. 46.76 ± 4.51), P < 0.001] legs was also found to be significantly reduced in study group in comparison to control group. CONCLUSION: Operating mechanical sewing machine by paddling chronically and arduously could have attributed to abnormal nerve conduction study parameters due to vibration effect of the machine on right and left common peroneal nerves. The results of present study follow the trend towards presymptomatic or asymptomatic neuropathy similar to subclinical neuropathy.

Nerve conduction studies in lower limb of elite Nepalese football players: an insight into neural adaptations.

BACKGROUND: The study was aimed to assess somatic neural alterations in lower limbs of elite Nepalese football players by comparing their nerve conduction parameters with non-athletic controls. METHODS: Players (N.=27, age 22.74±2.52 yrs.) with excellent cardio-respiratory fitness and presenting no signs of injuries, and sedentary controls (N.=29, age 23.41±2.95 yrs.) were recruited for the study. Standard nerve conduction techniques were applied to evaluate posterior tibial and sural nerves in the dominant and non-dominant limbs of each individual. Conduction velocity, onset latency, amplitude and duration of the motor and sensory evoked responses were recorded. RESULTS: The players had significantly lower resting mean heart rate, systolic and diastolic blood pressure than controls. Tibial compound muscle action potential (CMAP) showed higher amplitude as compared to controls; tibial proximal CMAP amplitude [(13.624±4.57) vs. (10.810±4.62) mV, P=0.035] of dominant leg, tibial proximal [(13.893±4.60) vs. (11.083±4.51) mV, P=0.045] and distal [(16.388±3.62) vs. (13.958±4.65) mV, P=0.049] amplitude of non-dominant leg. Likewise, players had significantly shorter tibial CMAPs duration of each lower limb compared with corresponding limb of controls. Sural nerve of non-dominant leg revealed shortened sensory nerve action potential duration [(1.729±0.25) vs. (1.904±0.289) ms, P=0.018]. CONCLUSIONS: Increased tibial CMAP amplitude and decreased CMAP duration in players suggest excitation of more number of motor units and higher synchronicity of muscle fibers' discharge than in controls respectively. Higher amplitude can also be attributed to increase in muscle fiber size and/or efficiency of neuromuscular transmission. Increased synchronicity indirectly reflects narrow range of conduction velocity among tibial neurons. The adaptive changes in somatic nerves need more crucial research for exact identification of sites and the structures responsible.

Somatic neural alterations in non-diabetic obesity: a cross-sectional study.

BACKGROUND: Reports on alterations in somatic neural functions due to non-diabetic obesity, a major risk factor for diabetes, are few and still a matter of debate. Nevertheless, to our knowledge, reports lack any comments on the type of somatic nerve fibers affected in non-diabetic obesity. Therefore, this study aimed to find out the alteration in somatic neural functions in non-diabetic obese persons if any. METHODS: The study was conducted on 30 adult non-diabetic obese persons (mean age 32.07 ± 7.25 years) with BMI > 30 Kg/m2 (mean BMI 30.02 ± 2.89 Kg/m2) and 29 age- and sex-matched normal weight controls (mean age 30.48 ± 8.01 years) with BMI: 18-24Kg/m2 (mean BMI 21.87 ± 2.40 Kg/m2). Nerve conduction study (NCS) variables of median, tibial and sural nerves were assessed in each subject using standard protocol. The data were compared by Mann Whitney 'U' test. RESULTS: In comparison to normal weight persons, obese had lower compound muscle action potential (CMAP) amplitudes of right median [9.09(7.62-10.20) Vs 10.75(8.71-12.2) mV, p = 0.025] and bilateral tibial nerves [Right: 8.5(7.04-11.18) Vs 12.1(10.55-15) mV, p < 0.001 and left 9.08(6.58-11.65) Vs 13.05(10.2-15.6) mV, p = 0.002]. Furthermore, obese persons had prolonged CMAP durations of right and left median [10.5(9.62-12) Vs 10(8.4-10.3) ms, p = 0.02 and 10.85(10-11.88) Vs 10(9-10.57) ms, p = 0.019] and right tibial [10(9-11) 8.5(7.92-10) ms, p = 0.032] nerves. Sensory NCS (sural nerve) also showed diminished sensory nerve action potential (SNAP) amplitude [16(12.08-18.21) vs 22.8(18.3-31.08) µV, p < 0.001] and prolonged duration. However, onset latencies and conduction velocities for all nerves were comparable between the groups. CONCLUSION: This study documents subclinical peripheral nerve damage in non-diabetic obese with abnormal NCS parameters; shorter amplitudes and prolonged CMAP and SNAP durations. The reduced amplitudes of mixed and sensory nerves might be due to decreased axonal number stimulation or actual decrease in number of axonal fibers, or defect at NMJ in non-diabetic obese. Prolonged durations but normal onset latencies and conduction velocities strongly suggest involvement of slow conducting fibers.

Learning approach among health sciences students in a medical college in Nepal: a cross-sectional study.

BACKGROUND: Many factors shape the quality of learning. The intrinsically motivated students adopt a deep approach to learning, while students who fear failure in assessments adopt a surface approach to learning. In the area of health science education in Nepal, there is still a lack of studies on learning approach that can be used to transform the students to become better learners and improve the effectiveness of teaching. Therefore, we aimed to explore the learning approaches among medical, dental, and nursing students of Chitwan Medical College, Nepal using Biggs's Revised Two-Factor Study Process Questionnaire (R-SPQ-2F) after testing its reliability. METHODS: R-SPQ-2F containing 20 items represented two main scales of learning approaches, deep and surface, with four subscales: deep motive, deep strategy, surface motive, and surface strategy. Each subscale had five items and each item was rated on a 5-point Likert scale. The data were analyzed using Student's t-test and analysis of variance. Reliability of the administered questionnaire was checked using Cronbach's alpha. RESULTS: The Cronbach's alpha value (0.6) for 20 items of R-SPQ-2F was found to be acceptable for its use. The participants predominantly had a deep approach to learning regardless of their age and sex (deep: 32.62±6.33 versus surface: 25.14±6.81, P<0.001). The level of deep approach among medical students (33.26±6.40) was significantly higher than among dental (31.71±6.51) and nursing (31.36±4.72) students. In comparison to first-year students, deep approach among second-year medical (34.63±6.51 to 31.73±5.93; P<0.001) and dental (33.47±6.73 to 29.09±5.62; P=0.002) students was found to be significantly decreased. On the other hand, surface approach significantly increased (25.55±8.19 to 29.34±6.25; P=0.023) among second-year dental students compared to first-year dental students. CONCLUSION: Medical students were found to adopt a deeper approach to learning than dental and nursing students. However, irrespective of disciplines and personal characteristics of participants, the primarily deep learning approach was found to be shifting progressively toward a surface approach after completion of an academic year, which should be avoided.

The conserved Phe GH5 of importance for hemoglobin intersubunit contact is mutated in gadoid fish.

BACKGROUND: Functionality of the tetrameric hemoglobin molecule seems to be determined by a few amino acids located in key positions. Oxygen binding encompasses structural changes at the interfaces between the α1ß2 and α2ß1 dimers, but also subunit interactions are important for the oxygen binding affinity and stability. The latter packing contacts include the conserved Arg B12 interacting with Phe GH5, which is replaced by Leu and Tyr in the αA and αD chains, respectively, of birds and reptiles. RESULTS: Searching all known hemoglobins from a variety of gnathostome species (jawed vertebrates) revealed the almost invariant Arg B12 coded by the AGG triplet positioned at an exon-intron boundary. Rare substitutions of Arg B12 in the gnathostome ß globins were found in pig, tree shrew and scaled reptiles. Phe GH5 is also highly conserved in the ß globins, except for the Leu replacement in the ß1 globin of five marine gadoid species, gilthead seabream and the Comoran coelacanth, while Cys and Ile were found in burbot and yellow croaker, respectively. Atlantic cod ß1 globin showed a Leu/Met polymorphism at position GH5 dominated by the Met variant in northwest-Atlantic populations that was rarely found in northeast-Atlantic cod. Site-specific analyses identified six consensus codons under positive selection, including 122ß(GH5), indicating that the amino acid changes identified at this position may offer an adaptive advantage. In fact, computational mutation analysis showed that the replacement of Phe GH5 with Leu or Cys decreased the number of van der Waals contacts essentially in the deoxy form that probably causes a slight increase in the oxygen binding affinity. CONCLUSIONS: The almost invariant Arg B12 and the AGG codon seem to be important for the packing contacts and pre-mRNA processing, respectively, but the rare mutations identified might be beneficial. The Leu122ß1(GH5)Met and Met55ß1(D6)Val polymorphisms in Atlantic cod hemoglobin modify the intradimer contacts B12-GH5 and H2-D6, while amino acid replacements at these positions in avian hemoglobin seem to be evolutionary adaptive in air-breathing vertebrates. The results support the theory that adaptive changes in hemoglobin functions are caused by a few substitutions at key positions.