Interaction of α-crystallin with some small molecules and its effect on its structure and function

BACKGROUND

α-Crystallin acts like a molecular chaperone by interacting with its substrate proteins and thus prevents their aggregation. It also interacts with various kinds of small molecules that affect its structure and function.

SCOPE OF REVIEW

In this article we will present a review of work done with respect to the interaction of ATP, peptide generated from lens crystallin and other proteins and some bivalent metal ions with α-crystallin and discuss the role of these interactions on its structure and function and cataract formation. We will also discuss the interaction of some hydrophobic fluorescence probes and surface active agents with α-crystallin.

MAJOR CONCLUSIONS

Small molecule interaction controls the structure and function of α-crystallin. ATP and Zn+2 stabilize its structure and enhance chaperone function. Therefore the depletion of these small molecules can be detrimental to maintenance of lens transparency. However, the accumulation of small peptides due to protease activity in the lens can also be harmful as the interaction of these peptides with α-crystallin and other crystallin proteins in the lens promotes aggregation and loss of lens transparency. The use of hydrophobic probe has led to a wealth of information regarding the location of substrate binding site and nature of chaperone-substrate interaction. Interaction of surface active agents with α-crystallin has helped us to understand the structural stability and oligomeric dissociation in α-crystallin.

GENERAL SIGNIFICANCE

These interactions are very helpful in understanding the mechanistic details of the structural changes and chaperone function of α-crystallin. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.

Therapeutic effects of functional electrical stimulation on motor cortex in children with spastic Cerebral Palsy

In the present study we have evaluated the electroencephalogram (EEG) signal recorded during ankle dorsal and plantar flexion in children with spastic Cerebral Palsy (CP) after Functional Electrical Stimulation (FES) of the Tibialis Anterior (TA) muscles. The intervention group had 10 children with spastic diaplegic/hemiplegic CP within the age group of 5 to 14 years of age who received both FES for 30 minutes and the conventional physiotherapy for 30 minutes a day, while the control group had 5 children who received only conventional physiotherapy for 60(30 + 30) minutes a day only. Both group were treated for 5 days a week, up to 12 weeks. The EEG data were analyzed for Peak Alpha Frequency (PAF), sensorimotor rhythm (SMR), mu wave suppression and power spectral density (PSD) of all the bands. The results showed a decrease in SMR and mu wave suppression in the intervention group as compared to the control group, indicating a positive/greater improvement in performance of motor activities. Therefore, from this study we could conclude that FES combined with conventional physiotherapy improves the motor activity in children with spastic CP.

A novel fibrinogen γ chain frameshift deletion (c.637delT) in a patient with hypodysfibrinogenemia associated with thrombosis

Inherited fibrinogen (FG) disorders are rare and result in quantitative or/and qualitative FG deficiency. While the majority of patients with clinically relevant FG deficiencies demonstrate a bleeding phenotype, a subset of patients are at increased risk of thrombosis.

PATIENTS AND METHODS

We report a 54-years old man presenting with a thrombophilic phenotype characterized by two episodes of unprovoked venous thrombosis and a deep vein thrombosis several weeks after myocardial infarction. Recently, he developed A. carotis communis thrombosis and died. Coagulation tests were done using standard procedures. FG genes were screened using direct sequencing. Effect on fibrin clot structure was analyzed by scanning electron microscopy (SEM) and FG chain polymerization was analysed using SDS-PAGE.

RESULTS

While thrombophilia testing was negative, we found a decreased concentration of clottable FG (126-148 mg/dl) compared to FG antigen (182-194 mg/dl of normal). The thrombin time was slightly prolonged, while aPTT and reptilase time were within the normal range. A novel deletion in FGG gene (c.637delT) resulting in a frameshift and the premature termination of the γ chain at amino acid position p.228 was identified. SDS-PAGE showed a time-shift in γ-γ and α-α cross linking. SEM showed no statistically significant differences between the patient´s and a healthy control´s fibrin clot structure.

CONCLUSIONS

In addition to the reduction of FG concentration expected by the nature of the mutation also a functional defect (hypodysfibrinogenemia) was found. Moreover this mutation seems to increase the risk of thrombosis warranting long term anticoagulation possibly in a combination with antiplatelet drugs.

Neoplasm-induced bleeding in inherited, heterozygous FXIII-A deficiency

Inherited mild factor XIII deficiency belongs to one of the most underdiagnosed bleeding disorders so far. This is, because most patients do not develop bleeding complications in daily life.

A man (age: 64 years) without a history of bleeding presented with painful swelling of neck, weight loss, anemia and episodic bleeding from the right tonsil necessitating tonsillectomy. Histologic and immunohistochemical evaluation revealed cytokeratinpositive epitheloid angiosarcoma. Blood coagulation status showed significantly elevated D-dimer and decreased FXIII levels (FXIII-activity 35%, FXIIIA-Ag 16–26%). Plasma mixing studies excluded neutralizing antibodies against FXIII.

A novel heterozygous F13A1 gene nonsense mutation (p.Glu103Ter, c.307G>T) was found confirming heterozygous FXIII-A deficiency. The same mutation was detected in two further asymptomatic relatives. For further clinical management the patient was transfused with FXIII-concentrate and showed an adequate increase of FXIII ruling out FXIII deficiency to be induced by increased turnover. Despite this haemostatic management and antifibrinolytic treatment the patient had to undergo several revisions due to delayed, Hb relevant bleeding after cervical lymph nodes extirpation and resection of tonsil. Two chemotherapy cycles with paclitaxel and palliative radiotherapy of the neck area were performed, but the patient died unfortunately two months after diagnosis.

It is a unique case showing the combination of a highly aggressive angiosarcoma and presence of inherited FXIII deficiency. It is also a rare example demonstrating the benefit of FXIII genotyping besides the expected acquired FXIII deficiency possibly due to neoplasm induced increased consumption by elevated crosslinking of fibrin fibers.

Novel point mutation in fibrinogen (Innsbruck; BβArg44Gly). Phenotypic differences compared to another mutation (fibrinogen Nijmegen) at the same position

This is a report of a novel fibrinogen point mutation (fibrinogen Innsbruck), a C/G point mutation at position 220 of exon two of the fibrinogen Bβ-chain leading to BβArg44Gly. The heterozygous mutation was found in a 16-year-old adolescent, hospitalized for the management of juvenile depression, who suffered from multiple epistaxis episodes during his stay at the university hospital in Innsbruck, Austria. Fibrinogen (based on the Clauss method) and fibrinogen antigen levels were highly discrepant (86 vs. 223 mg/dl) with thrombin time and reptilase time being in the respective upper reference ranges. Densitometric analysis of electrophoretic band pattern showed a reduction of α-polymers, indicating an impaired fibrin polymerization. This is in agreement with structural analysis, which showed a disturbance of the flexibility and structure of the region surrounding the fibrinoeptide B cleavage site. Fibrinogen Nijmegen, a mutation at the same position, is causative for thrombosis, whereas fibrinogen Innsbruck appears to lead to a bleeding tendency, illustrating that even mutations at the same position can cause contrary symptoms.

Novel point mutation in fibrinogen (Innsbruck; BβArg44Gly)

This is a report of a novel fibrinogen point mutation (fibrinogen Innsbruck), a C/G point mutation at position 220 of exon two of the fibrinogen B|-chain leading to B|3Arg44Gly. The heterozygous mutation was found in a 16-year-old adolescent, hospitalized for the management of juvenile depression, who suffered from multiple epistaxis episodes during his stay at the university hospital in Innsbruck, Austria. Fibrinogen (based on the Clauss method) and fibrinogen antigen levels were highly discrepant (86 vs. 223 mg/dl) with thrombin time and reptilase time being in the respective upper reference ranges. Densitometric analysis of electrophoretic band pattern showed a reduction of a-polymers, indicating an impaired fibrin polymerization. This is in agreement with structural analysis, which showed a disturbance of the flexibility and structure of the region surrounding the fibrinoeptide B cleavage site. Fibrinogen Nijmegen, a mutation at the same position, is causative for thrombosis, whereas fibrinogen Innsbruck appears to lead to a bleeding tendency, illustrating that even mutations at the same position can cause contrary symptoms.

Prevention of Parastomal Hernia Using Pre-peritoneal Mesh - Long Term Outcome of a Prospective Study

BACKGROUND

Parastomal hernia is a frequent complication after stoma formation. The objective of this prospective study was to find long-term outcome of prophylactic mesh placement in the pre-peritoneal space in order to prevent parastomal hernia.

METHODS

Patients undergoing elective formation of permanent stoma were included in the study. A polypropylene mesh was placed in the pre-peritoneal space without any anchoring stitches and bowel was taken out through a central circular hole made in the mesh. These patients were followed up for 5 years-by clinical examination and CT scan when needed.

RESULTS

A total of 42 patients were included in the study. These patients were followed up for a median period of 60 months (range 32-100 months). Twelve patients died before the 5-year follow up due to causes unrelated to stoma. As two patients were unable to be contacted, 28 patients remained in the long-term follow up. Three cases of parastomal hernia were detected after 5 years. None of these patients required repairing of the parastomal hernia. However, a previous study conducted 3 years ago found 4 cases of parastomal hernia that was treated by resiting the stomas. Therefore the total number of parastomal hernia detected in our series is 7 (incidence 25%).

CONCLUSION

Putting a pre-peritoneal polypropylene mesh is an easy, quick and inexpensive method, and easy to learn. The outcome is better than creating stomas without mesh, but further studies are needed to explore potential benefits of different types of mesh and their methods of positioning and anchoring.

Prevention of Parastomal Hernia Using Pre-peritoneal Mesh - Long Term Outcome of a Prospective Study

BACKGROUND

Parastomal hernia is a frequent complication after stoma formation. The objective of this prospective study was to find long-term outcome of prophylactic mesh placement in the pre-peritoneal space in order to prevent parastomal hernia.

METHODS

Patients undergoing elective formation of permanent stoma were included in the study. A polypropylene mesh was placed in the pre-peritoneal space without any anchoring stitches and bowel was taken out through a central circular hole made in the mesh. These patients were followed up for 5 years-by clinical examination and CT scan when needed.

RESULTS

A total of 42 patients were included in the study. These patients were followed up for a median period of 60 months (range 32-100 months). Twelve patients died before the 5-year follow up due to causes unrelated to stoma. As two patients were unable to be contacted, 28 patients remained in the long-term follow up. Three cases of parastomal hernia were detected after 5 years. None of these patients required repairing of the parastomal hernia. However, a previous study conducted 3 years ago found 4 cases of parastomal hernia that was treated by resiting the stomas. Therefore the total number of parastomal hernia detected in our series is 7 (incidence 25%).

CONCLUSIONS

Putting a pre-peritoneal polypropylene mesh is an easy, quick and inexpensive method, and easy to learn. The outcome is better than creating stomas without mesh, but further studies are needed to explore potential benefits of different types of mesh and their methods of positioning and anchoring.

Neoplasm-induced bleeding in inherited, heterozygous FXIII-A deficiency

Inherited mild factor XIII deficiency belongs to one of the most underdiagnosed bleeding disorders so far. This is, because most patients do not develop bleeding complications in daily life. Patient, methods: A man (age: 64 years) without a history of bleeding presented with painful swelling of neck, weight loss, anemia and episodic bleeding from the right tonsil necessitating tonsillectomy. Histologic and immunohistochemical evaluation revealed cytokeratin-positive epitheloid angiosarcoma. Blood coagulation status showed significantly elevated D-dimer and decreased FXIII levels (FXIII-activity 35%, FXIIIA-Ag 16-26%). Plasma mixing studies excluded neutralizing antibodies against FXIII.

RESULTS

A novel heterozygous F13A1 gene nonsense mutation (p.Glu103Ter, c.307G>T) was found confirming heterozygous FXIII-A deficiency. The same mutation was detected in two further asymptomatic relatives. For further clinical management the patient was transfused with FXIII-concentrate and showed an adequate increase of FXIII ruling out FXIII deficiency to be induced by increased turnover. Despite this haemostatic management and antifibrinolytic treatment the patient had to undergo several revisions due to delayed, Hb relevant bleeding after cervical lymph nodes extirpation and resection of tonsil. Two chemotherapy cycles with paclitaxel and palliative radiotherapy of the neck area were performed, but the patient died unfortunately two months after diagnosis.

CONCLUSIONS

It is a unique case showing the combination of a highly aggressive angiosarcoma and presence of inherited FXIII deficiency. It is also a rare example demonstrating the benefit of FXIII genotyping besides the expected acquired FXIII deficiency possibly due to neoplasm induced increased consumption by elevated crosslinking of fibrin fibers.

Assessment of stigma associated with tuberculosis in Mexico

BACKGROUND

Stigma is a major barrier to health care access and impacts the quality of life for individuals affected by tuberculosis (TB). Assessing TB stigma is essential to addressing health disparities. However, no such instrument was available in Mexico at the time of our study. This study examined the adaptability of the TB and human immunodeficiency virus (HIV) stigma scales previously used in Thailand.

METHODS

The original scale, developed in English, was linguistically adapted to Spanish and administered to 217 individuals affected by TB in five states in Mexico. The TB-HIV stigma subscales were designed to assess individual and community perspectives. Additional data collected included general information and socio-demographics. Assessment of psychometric properties included basic statistical tests, evaluation of Cronbach's alpha and factor analysis.

RESULTS

We found no significant statistical differences associated with higher stigma scores by location, age, marital status, education and stigma scores. Factor analysis did not create any new factors. Internal consistency reliability coefficients were satisfactory (Cronbach α = 0.876-0.912).

CONCLUSION

The use of the stigma scales has implications for 1) health improvements, 2) research on stigma and health disparities, and 3) TB and HIV stigma interventions. Further research is needed to examine transferability among larger and randomly selected Spanish-speaking populations.

A novel nested reverse-transcriptase polymerase chain reaction method for rapid hepatitis C virus detection and genotyping

PURPOSE

Rapid and specific detection of viral nucleic acid is increasingly important in the diagnosis of infectious diseases. The objective was to develop a rapid, efficient process of nucleic acid based detection of hepatitis C virus (HCV) infection for its diagnosis and treatment follow-up.

MATERIALS AND METHODS

A two-step nested reverse-transcriptase polymerase chain reaction (RT-PCR) has been standardised on a sample set of 125 individuals from different liver clinics in Kolkata. The method utilises a novel fast nested RT-PCR for HCV detection and genotyping from HCV infected patient plasma with high processivity.

RESULTS

The overall time required from ribonucleic acid (RNA) isolation to nested PCR amplified product detection is reduced to 42% when compared with conventional nested RT-PCR amplification. The method is sensitive as conventional PCR and detected all HCV RNA positive samples. Sequencing, phylogenetic analysis of the PCR amplified product by this method showed concordant genotypes with conventional PCR.

CONCLUSION

Though being a two-step process, this method is fast, cost-efficient, reliable and feasible for regular HCV RNA screening and apt even in resource limited settings. This method could be translated to regular nucleic acid screening for other infectious diseases as regular PCR regimen.

Design and development of an in-line sputtering system and process development of thin film multilayer neutron supermirrors

Neutron supermirrors and supermirror polarizers are thin film multilayer based devices which are used for reflecting and polarizing neutrons in various neutron based experiments. In the present communication, the in-house development of a 9 m long in-line dc sputtering system has been described which is suitable for deposition of neutron supermirrors on large size (1500 mm × 150 mm) substrates and in large numbers. The optimisation process of deposition of Co and Ti thin film, Co/Ti periodic multilayers, and a-periodic supermirrors have also been described. The system has been used to deposit thin film multilayer supermirror polarizers which show high reflectivity up to a reasonably large critical wavevector transfer of ∼0.06 Å(-1) (corresponding to m = 2.5, i.e., 2.5 times critical wavevector transfer of natural Ni). The computer code for designing these supermirrors has also been developed in-house.

Cause of and contributing factors to maternal deaths; a cross-sectional study using verbal autopsy in four districts in Bangladesh

Verbal autopsy used at community level is an accepted method to identify cause of death and factors contributing to death. Maternal deaths occurring in four districts in Bangladesh over a period of 24 months were identified and community health workers were trained to conduct a verbal autopsy. Of 571 maternal deaths identified almost half (273, 47.8%) occurred at facility level, 97 (17.0%) died en route to a healthcare facility and 201 (35.2%) maternal deaths occurred at home. The majority of maternal deaths occurred in the postpartum period (78.8%) in the first 6 hours after giving birth (41.6% of all postpartum deaths). Women who had accessed care at a healthcare facility were less likely to die in the first 6 hours when compared with women who died at home (relative risk 0.70; 95% confidence interval 0.56-0.88) 70.4% (402) of deaths were classified as direct maternal deaths, 12.4% (71) as indirect and 13.8% (79) as unspecified. The most common cause of death was haemorrhage (38%), followed by eclampsia (20%) and sepsis (8.1%). Almost three out of four women who died had sought care for complications during the index pregnancy. Most mothers who died in Bangladesh had accessed care. It is now crucial that the quality of care received at health facility level is improved. This includes a refocus on strengthening healthcare providers' knowledge and skills to recognise and manage complications and provide emergency obstetric care. The enabling environment must be in place as well as ensuring a fully functional referral pathway between healthcare facilities.

The many faces of Pulmonary Langerhans Cell Histiocytosis

Langerhans Cell Histiocytosis is a rare disease with variable presentation and prognosis in adults and in children. Histiocytosis of the ocular choroidal tissue has never been reported before in adults. We present two cases, one with choroidal involvement with asymptomatic nodulo-cystic changes in the lungs and another case with advanced single organ pulmonary involvement. We discuss the various treatment modalities and highlight the lack of adequate guidelines to treat adults. Most of the current guidelines are based on evidence derived from pediatric literature. We would also like to draw attention to the asymptomatic nature of the lung involvement and suggest that imaging of the lung be obtained in all cases of Langerhans Cell Histiocytosis.