Assessment of Performance of Blind Center Lathe Operators

Although sight is generally considered to be necessary for the performance of most industrial jobs, this study found that blind persons can be trained to operate a center lathe and to perform various tasks on it accurately. The study assessed the blind subjects’ efficiency of performance of tasks when they utilized various adjustments to the lathe and to procedures that had been developed earlier specifically for blind people. It was found that the efficiency of the blind subjects, compared to that of sighted lathe operators, was 85 percent for moderately complex jobs. The factors of complexity, repetition, and mode of presentation of specifications had some bearing on the speed of work. The study demonstrated that even under adverse conditions, blind lathe operators can achieve satisfactory results.

Modular Concept in a Multi-Functional above Knee Prosthesis

Conventional designs of above knee prostheses do not permit squatting and sitting cross-legged (SCL) on the floor. These postures are commonly adopted in India and other Afro-Asian countries. A new prosthesis design permitting these postures has been evolved. Further, a modular system has been prepared to fit into a number of different leg sizes. As a result of the new technology, the ankle remains fixed in normal walking and automatically flexes during squatting. Also for SCL, the thigh rotation is automatic. Thus, no hand manipulations are needed and the movements, both going down and arising are similar to normal movements.

227 MESENCHYMAL STEM CELL ISOLATION AND CULTURE FROM ADIPOSE TISSUE OF A DEAD DOG

Isolation of cells or stem cells from clinically dead animals may serve applications such as revival of the animal through somatic cell nuclear transfer (SCNT) or cryopreservation of their cells for a long period so that cells can be used in the future. Thus, combining isolation of cells from clinically dead animals and SCNT of germplasm of elite animals could benefit research into endangered or extinct species. In the present study, we tried to isolate and culture adipose-derived mesenchymal stem cells (ADSC) from a clinically dead dog. Adipose tissues were collected surgically from the abdomen of a dead dog after 3 h and processed tissues within 10 h of death. The isolated tissues were washed in 70% ethanol for 30 s and washed 5 times in Dulbecco’s PBS supplemented with 50 µg mL–1 gentamicin. These fat tissues were minced to very small pieces and washed in DMEM by centrifugation at 800 rpm for 3 min. The tissue pellet was subjected to enzymatic digestion (collagenase 1 mg mL–1 of Dulbecco’s PBS) at 37°C in CO2 incubator for 1 h, with intermittent shaking after every 10 min. The digestive enzyme was inactivated by equal volume of DMEM/F-12 supplemented with fetal bovine serum (20%) and centrifuged at 1000 rpm for 10 min. The pellet was resuspended in DMEM/F-12 with 10% fetal bovine serum and cultured at 1 × 106 cells mL–1 in 25-cm2 tissue culture flasks. The medium was changed after every 48 h. Mesenchymal stem cells (MSC) were observed under an inverted microscope after 6 days. These cells were subcultured and a confluent monolayer was obtained. We have already standardized the protocol of MSC culture and characterisation as we are treating wounded and paralysed dogs using these MSC in a pet clinic. Characterisation of MSC was performed with specific surface marker genes of CD44, CD29, and CD166 in PCR and by immunocytochemistry of MSC-specific marker of CD44. Differentiation of these MSC into osteogenesis and chondrogenesis were observed after 3 weeks. Chondrogenic differentiation was confirmed by positive expression of chondrocyte-specific marker genes Aggrecan F-TTGGACTTTGGCAGAATACC and R-CTTCCACCAATGTCGTATCC and Collagen II F-AACCCTGGAACTGACGGAAT and R-CTCACCCGTTTGACCTTTCG primer in PCR. The MSC were cryopreserved after 80% confluency was reached. The monolayer cells were scraped out from the culture flask and pelleted down. The pellet was resuspended in DMEM containing 10% DMSO and 20% fetal bovine serum. The number of cells was determined by trypan blue staining using an automatic cell counter and 105 cells mL–1 were added to a 2-mL cryogenic vial. The cryogenic vials were kept in a cryobox at –80°C for slow cooling. Then these vials were transferred to liquid nitrogen tanks after 12 h for long-term storage. We conclude that ADSC were successfully cultured from adipose tissue of a dog within 10 h of death and further subcultured under in vitro conditions. The cells could be used for SCNT to revive the dead animal and cryopreserve these cells for use in the future.

Type 1 and type 3 Gaucher disease in two siblings in a family: 2 unusual case reports

Gaucher disease (GD) is an autosomal recessive disorder, characterized by lack of acid β-glucosidase (glucocerebrosidase) enzyme resulting in accumulation of glucosylceramide in different organs. It is common in Ashkenazi Jews but rare in India. Around five hundred cases are identified and diagnosed in India. We are reporting two interesting cases of type 1 non-neuropathic and type 3 juvenile subacute neuropathic variant of adult Gaucher disease in two of three siblings in a family.

198 ISOLATION, CHARACTERIZATION, AND IN VITRO DIFFERENTIATION OF GOAT ADIPOSE-TISSUE-DERIVED MESENCHYMAL STEM CELLS INTO PANCREATIC ISLETS-LIKE CELLS

The present study was carried out for isolation of goat (Capra hircus) adipose-tissue-derived stem cells (gADSCs) from adipose tissue, their characterization, and in vitro differentiation of gADSCs into pancreatic islets-like cells by giving conditioned medium. Goat ADSCs were isolated from goat adipose tissue by the enzymatic digestion method and were enriched by filtering through a 41-μm filter. Thus, filtered cells resuspended in a cell culture flask containing growth enriching medium and cultured in 5% CO2 in air at 38.5°C. Goat ADSCs were characterised by amplification of mesenchymal stem cell specific markers i.e. CD29, CD34, CD44, CD90, and CD166 as positive markers and CD41 and CD71 as negative markers. Immunocytochemistry of mesenchymal stem cell was also carried out with specific markers CD44 and CD90. Goat ADSCs were further characterised by in vitro differentiating them into osteocytes, chondrocytes, and adipocytes. For in vitro differentiation of gADSCs into osteocytes gADSCs were supplemented with conditioned medium i.e. DMEM containing fetal bovine serum (FBS), dexamethazone, B-glycerol phosphate and L-ascorbic acid. Osteogenic differentiation was confirmed by positive Alizarin red S staining and amplification of Osteopontin and Collagen I genes. For differentiation into chondrocytes cells, gADSCs were incubated in DMEM/F12 containing dexamethazone, ITX, BMP-4, and FBS for 21 days. Differentiated cells were confirmed by positive Safranin O staining and expression of chondrocytes specific Collagen III and Aggrecan genes. For adipogenesis, gADSCs were incubated with DMEM/F12 containing FBS, dexamethasone, and ITX and differentiated cells were confirmed by positive Oil Red O staining and amplification of adipocytes specific genes i.e. LPL, PPRγ and PPRα. For in-vitro differentiation gADSCs into pancreatic islets-like cells on the third or fourth passage gADSCs were incubated in conditioned medium containing serum-free DMEM/F12 medium with glucose (17.5 mM) in the presence of nicotinamide (10 mM), activin-A (2 nM), exendin-4 (10 nM), pentagastrin (10 nM), retinoic acid (10 μM) and mercaptoethanol (20 μM). The in vitro differentiation gADSCs into pancreatic islets-like cells was confirmed by amplification of pancreatic endoderm specific genes i.e. igf-1, sst, ngn3, pdx-1, isl-1, c-kit, thy-1, and Glut-2, and no expression was detected for above endoderm specific genes in undifferentiated gADSCs. Pancreatic islets-like cells were further characterised by immunostaining and Western blotting of Pdx-1, insulin, and Islets-1 specific protein. It could be concluded that gADSCs was differentiated into different lineages and secretory insulin was produced from pancreatic islets-like cells.

204 ISOLATION, CHARACTERIZATION, AND DIFFERENTIATION OF ADIPOSE TISSUE DERIVED MESENCHYMAL STEM CELLS: AN AUTOLOGOUS TRANSPLANTATION TO PATIENTS

Adult stem cells derived from all possible sources of livestock serve as the best possible alternative to embryonic stem cells. The discovery of mesenchymal stem cells has provided the new horizon to stem cell therapy. Adipose tissue derived mesenchymal stem cell (ADSCs), an easy source of adult stem cell has created a lot of interest among researchers as patient specific treatment and autologous transplantation in animals is becoming a viable option. The proposed study was carried out for 1) isolation of ADSCs from dogs, suffering from hip dysplasia or from paraplegia, 2) ADSC characterisation and in vitro differentiation ability into osteocytes, chondrocytes, adipocytes and neurocytes specific cells. Adipose tissues were collected from belly/umbilical cord region. ADSCs were isolated by enzymatic digestion method followed by enriching through a 41 μm filter. Filtered cells were then resuspended in cell culture flasks containing growth enriching medium and cultured in 5% CO2 in air at 37°C for 5 days. ADSCs were characterised by amplification of mesenchymal stem cell specific markers i.e. CD29, CD44, CD90, and CD166 and by immunocytochemistry of mesenchymal stem cell specific protein i.e. CD44 and CD90. ADSCs were further in vitro differentiated. ADSCs derived osteocytes, chondrocytes, and adipocytes were validated through the amplification of specific markers of osteocytes (Osteopontin, Collagen I); chondrocytes (Aggrecan and Collagen II) and adipocytes (LPL, PPARα, PPARγ). Dog ADSCs were further autogenic transplanted into hip dysplasia and paraplegic patients. These patients recovered well one month from transplantation and were able to move freely. It may be concluded that these findings may have implications for defining the physiological roles of ADSCs in arthritis; orthopaedic ailments, joint regeneration, neuronal disorders, and several other applications leading to novel therapeutic opportunities.

Factors responsible for delayed enrollment for anti-retroviral treatment

BACKGROUND

Late presentation followed by delayed diagnosis and further delayed initiation of anti-retroviral therapy (ART) increases the risk of opportunistic infections and neoplasms among the HIV infected patients. Furthermore, this leads to not only poor response to therapy but also early death among them.

METHODS

An institution based cross-sectional study was undertaken to identify the factor(s) responsible for delayed registration for initiation of therapy among the HIV infected patients with absolute CD4 count <250 cells/μL based on self reports. ART naïve adult HIV patients (age ≥18 years) with baseline CD4 count of <250 cells/μL were included in this study.

RESULTS

Most patients 95 (95%) were unaware of the available 'Integrated Counseling and Testing Centres'. Although 13 (13%) respondents had multiple reasons for delayed enrollment, majority 47 (47%) of the delays were due to the physician's failure to suspect and refer them for HIV testing at the earliest opportunity. Other causes include health seeking behavior 13 (13%), fear of stigma 5 (5%), depression 3 (3%), and lack of family support 6 (6%).

CONCLUSIONS

Even though delays in pre-ART enrollment have been realized since long, prevention efforts are poor, mostly due to the lack of understanding of the nature of the problem in its social context. Lack of clinical suspicion for HIV infection at the primary and secondary levels of health care still remains the most important reason for the delay. In order to prevent these delays in enrollments, intervention efforts need to be focused on not only the people infected with HIV but the primary health care providers as well, especially the practicing physicians.

Castlemans disease in HIV infected patient from eastern India

Castlemans disease is a rare lymphoproliferative disorder. We report a patient of Castlemans disease with advanced HIV infection who responded well to conventional HAART. This case is interesting because of the rarity of the disease in the eastern part of India and its good out come with antiretroviral therapy.

Studies on the membrane integrity of human sperm treated with a new injectable male contraceptive

BACKGROUND

The aim of this study was to evaluate the integrity of sperm surface characteristics in the presence of a new male contraceptive, RISUG [1 mg styrene maleic anhydride (SMA)/100 microl dimethylsulphoxide (DMSO) in 1 ml sperm solution].

METHODS

Progressively motile human sperm were treated in vitro with RISUG. The cells were analysed for the release of 5'-nucleotidase (5'-NT) (a plasma membrane marker) using 3 mmol/l 5'-AMP and 3 mmol/l beta-glycerophosphate as substrates. Hyaluronidase (an acrosomal membrane marker) was analysed using hyaluronic acid as a substrate. The contents of free and total acrosin, and % proacrosin (all acrosome markers) were assayed using 0.5 mmol/l alpha-N-benzoyl-L-arginine ethylester (BAEE).

RESULTS

RISUG caused almost complete disintegration of the plasma membrane leading to significant (P < 0.0001) release of 5'-NT into the surrounding media. Complete dissolution of the acrosome with concomitant vesiculation of the membrane system, as judged from the loss of hyaluronidase, was observed. Total acrosin content in the sperm was also reduced to almost 10%, and proacrosin dropped to 13.2% in the presence of RISUG in comparison to 90.2% in control (P < 0.0001), indicating dispersion of acrosomal contents.

CONCLUSION

Under in vitro conditions, RISUG, at a concentration of 1 mg SMA dissolved in 100 microl of DMSO, caused significant damage to the acrosome and its contents, indicating loss of functional ability of sperm.

Mucocutaneous manifestations of HIV infection

BACKGROUND AND AIMS

Human immunodeficiency virus (HIV) is associated with various mucocutaneous features, which may be the first pointer towards the existence of HIV infection. This study was done to note the different mucocutaneous lesions present in the HIV population in eastern India.

METHODS

Four hundred and ten HIV seropositive patients attending the outpatient and inpatient departments were included in the study.

RESULTS

Out of 410 HIV positives, 40% had mucocutaneous involvement at presentation. The mean age of the study population was 29 years and male to female ratio was 2.5:1. The common mucocutaneous morbidities included oral candidiasis (36%), dermatophytosis and gingivitis (13% each), herpes zoster (6%), herpes simplex and scabies (5% each). A striking feature, noted in 36% males, was straightening of hairs. Genital herpes was the commonest genital ulcer disease. Lesions associated with declining immunity included oral candidiasis, oral hairy leukoplakia and herpes zoster with median CD4 counts of 98, 62 and 198/ L respectively.

CONCLUSION

Early recognition of mucocutaneous manifestations and associated STDs help in better management of HIV/AIDS.

People living with HIV infection / AIDS - a study on lymph node FNAC and CD4 count

Between July 1997 and December 2000, 1616 HIV seropositive persons were identified by Western Blot test at the School of Tropical Medicine, Kolkata. Four hundred seventy two (29.2%) of them had generalized lymphadenopathy. CD4 count could be done in only 54 of these 472 subjects (11.4%). These 54 patients, consisting of 40 males (74%) and 14 females (26%) were the subjects of the study. Their mean age was 29.5 years. In all these subjects, FNAC was done from the enlarged lymph nodes (non-inguinal). Reactive hyperplasia was seen in 30 cases (55.5%) whose absolute CD4 count varied between 411-945 cells/microL (median value 670 cells/microL). Evidence of tuberculous lymphadenitis was detected in 22 (41%) with CD4 counts varying between 113 and 422 cells/microL (median value 212 cells/microL). Non-Hodgkin lymphoma was diagnosed in 2 cases (3.7%) with CD4 count 79-113 cells/microL. All patients had evidence of HIV-1 infection, excepting one case of dual infection (HIV-1 and 2).

A proton NMR study of the effect of a new intravasal injectable male contraceptive RISUG on seminal plasma metabolites

Nuclear magnetic resonance (NMR) spectroscopy was used to quantify citrate, glucose, lactate, glycerophosphorylcholine and choline in seminal plasma from subjects injected with a new male contraceptive RISUG, a copolymer of styrene maleic anhydride dissolved in dimethyl sulphoxide, and in seminal plasma from normal ejaculates. No significant difference in the concentration of citrate was observed between the groups, indicating that the prostate is not affected by the contraceptive. The concentrations of glucose, lactate, glycerophosphorylcholine and choline were significantly lower (P < 0.01) in subjects injected with RISUG compared with controls. In addition, metabolite ratios such as choline:citrate, citrate:lactate, choline:lactate and glycerophosphorylcholine:choline were calculated. Citrate:lactate and glycerophosphorylcholine:choline ratios were significantly lower in RISUG-injected subjects than in controls (P < 0.01), thereby indicating the occurrence of partial obstructive azoospermia. The most important finding of the present study was that the intervention of RISUG in the vas deferens even for a period as long as 8 years is absolutely safe and does not lead to prostatic diseases.

Differential decline in Leishmania membrane antigen-specific immunoglobulin G (IgG), IgM, IgE, and IgG subclass antibodies in Indian kala-azar patients after chemotherapy

Pathogenesis in kala-azar is associated with depressed cellular immunity and significant elevation of antileishmanial antibodies. Since these antibodies are present even after cure, analysis of the parasite-specific isotypes and immunoglobulin G (IgG) subclasses in kala-azar patients may shed new light on the immune responses during progression and resolution of infection. Using leishmanial membrane antigenic extracts, we investigated the relative levels of specific IgG, IgM, IgA, IgE, and IgG subclasses in Indian kala-azar patient sera during disease, drug resistance, and cure. Acute-phase sera showed strong stimulation of IgG, followed by IgE and IgM and lastly by IgA antibodies. IgG subclass analysis revealed expression of all of the subclasses, with a predominance of IgG1 during disease. Following sodium stibogluconate (SAG) resistance, the levels of IgG, IgM, IgE, and IgG4 remained constant, while there was a decrease in the titers of IgG2 and IgG3. In contrast, a significant (2.2-fold) increase in IgG1 was observed in these individuals. Cure, in both SAG-responsive and unresponsive patients, correlated with a decline in the levels of IgG, IgM, IgE, and all of the IgG subclasses. The stimulation of IgG1 and the persistence, most importantly, of IgE and IgG4 following drug resistance, along with a decline in IgE, IgG4, and IgG1 with cure, demonstrate the potential of these isotypes as possible markers for monitoring effective treatment in kala-azar.

Histoplasmosis in eastern India: the tip of the iceberg?

Systemic histoplasmosis has various clinical presentations and is of especially concern in immunocompromised patients. A high index of suspicion is required for its diagnosis. A total of 38 cases had been reported from India up to 1996. The most frequent occurrence of cases was around Calcutta in eastern India where the previous case was detected 20 years earlier. However, we have diagnosed 5 cases in the past 2 years from eastern India which are reported here. These cases may indicate under-diagnosis and under-reporting of histoplasmosis in India. All 5 patients had disseminated disease with multisystem involvement including 2 with bilateral adrenal enlargement. Two were diabetic and only 1 patient was infected with HIV.

Non-invasive reversal of intraluminal vas deferens polymer injection-induced azoospermia--technology

AIM

The rationale and technique underlying a novel concept of non-invasive removal of an intravasal vas deferens polymeric contraceptive drug to reverse drug injection-induced azoospermia are explained. Thus the conventional methods of surgical exploration to remove vas deferens plugs and intravasal injection of solvents to flush out contraceptive drugs are to be replaced by steps which will be readily accepted by subjects.

METHODS

The approach is based upon the non-invasive application of specific forces to various segments of the vas deferens so that non-sclerosing and non-tissue-adherent compounds, in particular styrene maleic anhydride (SMA) can be expelled. Forces are generated by palpation; percutaneous electrical stimulation; vibration application; and percussion. The forces help to propel the intravasal polymer towards the ejaculatory duct for expulsion during ejaculation. All aspects of the total technique are clinically acceptable, simple, atraumatic, unlikely to cause pain and discomfort even without tranquilizers, local or general anaesthetics. The procedure may be repeated several times in different sittings spaced apart by about one week to achieve adequate plug expulsion.

RESULTS

Model experiments demonstrated the feasibility of the concept. The polymer was nonadherent and could be moved within the vas deferens by the application of specific forces. Sufficient removal was possible to enable spermatic fluid to be transported along a region previously occupied by the polymer. A corroborating subhuman primate study by an independent investigator has shown that the semen profile becomes normal following the reversal.

CONCLUSION

Adoption of the new technique may provide a means of non surgical restoration of normal semen profile after a period of fertility control obtained by intravasal drug injection.

Multiple-pulse-mediated electrofusion of intact erythrocyte onto human term placental amnion

The creation of surface modified human term placental amnion by electrofusing human cells onto its surface has been thought of. A multiple-pulse electrofusion protocol with 10 square pulses of 10-micros pulse length, and electric field of 0.2 kV cm(-1), can make erythrocyte-amnion tissue electrofusion possible. The protocol devised merge the cell-tissue-adherence steps with fusogenic pulse. The finding opens up a new avenue of cell electrofusion onto human tissue with minimal procedural complexities.

Membrane microextension: a possible mechanism for establishing molecular contact in electrofusion

True cell membrane contact is an essential condition for electro-pulsed cell fusion, but initial morphological perturbation leading to true contact is still not clear. Dielectrophoresis mediated compression and fusogenic pulse induced compaction of cells led to rapid merger of tight membranes, and deprived direct microscopic view of surface membrane perturbation. Freely suspending cells with large and different cell-cell gaps may proceed to electrofusion with perturbed membrane and initiates fusion events at different time. These pulsed exposed cells can be used for capturing changes in the membrane surface and early electrofusion events. Early stage of fusion of freely suspended intact human erythrocytes exposed to single exponential decay pulse was studied by scanning electron microscopy (SEM). Field pulse induces small membrane bumps. Interaction of bumps on adjacent membranes lead to true membrane contact and form bridges between the membranes as microextension, combining both membranes into a topologically single structure. Some fusion products showed expanded fusion zones, which suggest indication of open lumen at contact area.

Theoretical aspects of single pulse induced modulation of cell-cell interactions favoring iso-electrofusion

A single pulse-mediated electrofusion of freely suspending widely separated cells could reduce steps in the protocol. Prediction of such electrofusion is still unsolved. In pre-pulse condition, quantitative estimation with three-layered model cell surface reveals electrostatic repulsion (due to negative surface charge) is the major hindrance to membrane-to-membrane contact. On theoretical grounds we predict that designed single high voltage pulsing on widely separated model cell surface can counteract the non-specific repulsive interaction and favor approach of two apposed membranes. But hydrodynamic modulation of pulse exposed cell surface interaction can hamper approach of membranes contact when cells are held at a gap of more than approximately 450 A.

Immunoglobulin subclass distribution and diagnostic value of Leishmania donovani antigen-specific immunoglobulin G3 in Indian kala-azar patients

Visceral leishmaniasis, or kala-azar, a fatal tropical disease, remains problematic, as early diagnosis is difficult and treatment often results in drug resistance and relapse. We have developed a sensitive enzyme-linked immunosorbent assay (ELISA), using leishmanial membrane antigenic extracts (LAg) to detect specific antibody responses in 25 untreated Indian visceral leishmaniasis patients. To investigate the pathogenetic significance of isotype markers in kala-azar, relative levels of specific immunoglobulin G (IgG), IgM, IgA, IgE, and IgG subclasses were analyzed under clinically established diseased conditions. Since LAg showed higher sensitivity for specific IgG than lysate, the immunoglobulin isotype responses were evaluated, with LAg as antigen. Compared to 60 controls, which included patients with malaria, tuberculosis, leprosy, and typhoid and healthy subjects, visceral leishmaniasis patients showed significantly higher IgG (100% sensitivity, 85% specificity), IgM (48% sensitivity, 100% specificity), and IgE (44% sensitivity, 98.3% specificity) responses. Low levels of IgA in visceral leishmaniasis patients contrasted with a 13-fold-higher reactivity in sera from patients with leprosy. Among IgG subclasses, IgG1, -3, and -4 responses were significantly higher in visceral leishmaniasis patients than in the controls. IgG2 response, however, was significantly higher (twofold) in leprosy than even visceral leishmaniasis patients. The rank orders for sensitivity (IgG = IgG1 = IgG3 = IgG4 > IgG2 > IgM > IgE > IgA) and specificity (IgM = IgG3 > IgE > IgG4 > IgG2 > IgG > IgG1 > IgA) for LAg-specific antibody responses suggest the potentiality of IgG3 as a diagnostic marker for visceral leishmaniasis.

Distribution of IgG subclasses in antimonial unresponsive Indian kala-azar patients

Sodium antimony gluconate (SAG) is the mainstay of treatment for visceral leishmaniasis (VL) or kala-azar. In view of the increasing incidence of refractoriness to SAG in India, we compared the levels of parasite-specific IgG and IgG subclasses in 20 longitudinally followed up kala-azar patients. In both SAG-responsive (n = 10) and unresponsive patients (n = 10), the levels of total IgG, IgG1, IgG2, IgG3 and IgG4 were increased, the rank order being IgG1 > IgG2 > IgG3 = IgG4. Following treatment, a significant decrease in total IgG and the four subclasses occurred in the SAG-responsive group, whereas in the SAG-unresponsive group these levels were unchanged or slightly increased. Therefore, monitoring of IgG1 and IgG2 levels in Indian kala-azar patients is a good serologic alternative to monitoring the disease status.

Reversibility with sodium bicarbonate of styrene maleic anhydride, an intravasal injectable contraceptive, in male rats

A copolymer of styrene and maleic anhydride (SMA) was dissolved in dimethyl sulphoxide (DMSO) and injected into the lumen of the vas deferens of rats. The polymer was retained in the lumen for a period of more than 90 days. Sodium bicarbonate (10%), pH 8.9, was used to flush the polymeric material from the vas deferens lumen. The reversibility and patency of the vas deferens was thus obtained. Sodium bicarbonate proved to be an effective alternative to dimethyl sulphoxide for reversal.