Infectious disease dynamics: What characterizes a successful invader?

Against the background of human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) and other potentially emerging (or re-emerging) infectious diseases, this review will focus on the properties which enable an infectious agent to establish and maintain itself within a specified host population. We shall emphasize that for a pathogen to cross a species barrier is one thing, but for it successfully to maintain itself in the new population is must have a 'basic reproductive number', R(0), which satisfies R(0) > 1. We shall further discuss how behavioural factors interweave with the basic biology of the production of transmission stages by the pathogen, all subject to possible secular changes, to determine the magnitude of R(0). Although primarily focusing on HIV and AIDS, we shall review wider aspects of these questions.

The epidemic behavior of the hepatitis C virus

Hepatitis C virus (HCV) is a leading worldwide cause of liver disease. Here, we use a new model of HCV spread to investigate the epidemic behavior of the virus and to estimate its basic reproductive number from gene sequence data. We find significant differences in epidemic behavior among HCV subtypes and suggest that these differences are largely the result of subtype-specific transmission patterns. Our model builds a bridge between the disciplines of population genetics and mathematical epidemiology by using pathogen gene sequences to infer the population dynamic history of an infectious disease.

Nitric oxide suppresses IL-8 transcription by inhibiting c-Jun N-terminal kinase-induced AP-1 activation

The role of activator protein-1 (AP-1) in tumor necrosis factor-alpha (TNF-alpha)-induced interleukin-8 (IL-8) gene expression was evaluated. We showed that TNF-alpha activates AP-1 in the transformed endothelial cell line ECV304 by transient transfections of IL-8 promoter construct pGL-3BF(2). Mutation of either the AP-1 site or the NF-IL-6 site on the IL-8 promoter suppressed the TNF-alpha-induced activation, suggesting cooperation between these transcription factors and transcription factor NF-kappaB. Overexpression of dominant negative mutants of c-Jun suppressed AP-1-driven transcription of the IL-8 promoter following stimulation by TNF-alpha, suggesting that cooperative interaction between AP-1 and NF-kappaB is essential for IL-8 transcription in the presence of TNF-alpha. We also showed that nitric oxide (NO), in the form of an exogenous NO donor, suppressed the level of activation of the AP-1 subunit, c-Jun, by down-regulation of c-Jun NH2 terminal kinase. This down-regulation could be the putative mechanism of action for NO-mediated inhibition of IL-8 secretion in activated endothelium. These observations suggest for the first time that NO has broad suppressive activities on various proinflammatory effectors in activated endothelium.

Mucocutaneous manifestations of secondary syphilis in north Indian patients: a changing scenario?

During the 1990s, no studies of various clinical presentations of syphilis have been published in the indexed literature. However, a change in the clinical profile of secondary syphilis was expected during the last decade with the rapid spread of the HIV epidemic. The objective was to study the mucocutaneous manifestations of secondary syphilis in patients attending the STD clinic at the Postgraduate Institute of Medical Education & Research Chandigarh, India, during the last decade and to compare them with other similar studies published during the 1980s. All patients who were diagnosed with secondary syphilis in our STD clinic from 1990 to 1999 were examined and investigated. Serological response was measured at 3, 6, 9, 12, and 24 months post-treatment or until serological negativity was reached. Fifty-three patients (males = 34, female = 19) during this period were found to have secondary syphilis. The most common symptoms were as follows-skin rash 38 (71.7%), lymphadenopathy 26 (49%), persistent chancre 4 (7.5%), nodular syphilides 2 (3.8%), lues maligna 2 (3.8%), patches in the oral mucosa 6 (11.3%), condylomata lata 14 (26.4%), split papules 2 (3.8%). Five patients had a thin and conspicuous genital scar of the healed primary chancre. Three patients were HIV seropositive (1 patient each with lues maligna, lichenoid, and nodular syphilides). With the spread of the HIV epidemic, atypical muco-cutaneous manifestations of secondary syphilis may be seen more frequently than before and may pose problems in diagnosis. In the present study, six patients had atypical manifestations, and three of them were HIV seropositive.

Cervical cerclage in the second trimester of pregnancy: a historical cohort study

OBJECTIVE

The purpose of this study was to compare second-trimester transvaginal cervical cerclage with conservative management on duration of pregnancy and perinatal outcome in patients with early or advanced cervical changes.

STUDY DESIGN

A historical cohort analysis was performed. Maternal and neonatal records between 1995 and 1999 were retrospectively reviewed for women presenting between 18 and 27 weeks of gestation with early cervical changes (length <3 cm, dilatation <2 cm, funneling of fetal membranes shown by transvaginal ultrasonography) (group 1, n = 31) and for women with advanced cervical effacement and dilatation (cervical dilatation > or =2 cm but < or =5 cm, fetal membranes visible) (group 2, n = 39). In each group, patients who underwent Shirodkar or McDonald cerclage were compared with patients treated conservatively with bed rest. Both groups also received multifactorial treatment with tocolytic agents, broad-spectrum antibiotics, and indomethacin. Outcome variables were analyzed for statistical significance by parametric and nonparametric methods.

RESULTS

Regardless of treatment method, patients with early cervical changes (group 1) were given a diagnosis earlier and delivered later in pregnancy compared with their counterparts who had advanced cervical changes (group 2) (P <.05). In both patients who underwent cerclage and those treated conservatively, the mean birth weight among surviving infants was higher and the mean neonatal intensive care unit stay was shorter in group 1 than in group 2 (P <.02). However, duration of maternal hospital stay and neonatal survival rates were not different. In both groups 1 and 2, the interval from treatment to delivery, the mean gestational age at delivery, and mean birth weight were increased, whereas neonatal intensive care unit stay was decreased by cerclage treatment (P <.05). In group 1, a higher percentage of patients treated with cerclage received antibiotics and indomethacin than did control subjects (P <.01), whereas in group 2, the use of multifactorial treatment was not different (P =.5). The duration of maternal hospital stay and neonatal survival did not differ significantly among patients treated conservatively or with cerclage.

CONCLUSIONS

Diagnosis of premature cervical changes by ultrasonography was correlated with treatment earlier in gestation and with a favorable impact on perinatal outcome in both patients treated with cerclage and those treated conservatively. Cervical cerclage was associated with an improved perinatal outcome (in comparison with conservative therapy) in women with early cervical changes detected by ultrasonography and in patients with advanced cervical dilatation and visible membranes. However, the apparent therapeutic effect of cerclage in patients with mild cervical incompetence may be due in part to an increased use of antibiotics and indomethacin in conjunction with cerclage.

A Semiparametric Deconvolution Model to Establish In Vivo–In Vitro Correlation Applied to OROS Oxybutynin

In vitro-in vivo correlation (IVIVC) models may be used to predict in vivo drug concentration-time profiles given in vitro release characteristics of a drug. This prediction is accomplished by incorporating in vitro release characteristics as an input function (A(vitro)) to a pharmacokinetics model. This simple approach often results in biased predictions of observed in vivo drug concentrations, and it can result in rejecting IVIVC. To solve this problem we propose a population IVIVC model that incorporates the in vitro information and allows one to quantify possibly changed in vivo release characteristic. The model assumes linear kinetics and describes the in vivo release as a sum of A(vitro) and a nonparametric function (A(d), a spline) representing the difference in release due to in vivo conditions. The function A(vitro) and its variability enter the model as a prior distribution. The function A(d) is estimated together with its intersubject variability. The number of parameters associated with A(d) defines the model: no parameters indicates perfect IVIVC, a large number of parameters indicates poor IVIVC. The number of parameters is determined using statistical model selection criteria. We demonstrate the approach to solve the IVIVC problem of an oral extended release oxybutynin form (OROS), administered in three pharmacokinetic studies. These studies present a particular challenging case; that is, the relative bioavailability for the OROS administration is >100% compared with that of the immediate-release form. The result of our modeling shows that the apparent lack of IVIVC can be overcome: in vivo concentration can be predicted (within or across data sets) based on in vitro release rate together with a simple form of systematic deviation from the in vitro release.

Efficacy and safety of sparfloxacin in combination with kanamycin and ethionamide in multidrug-resistant pulmonary tuberculosis patients: preliminary results

SETTING

Department of tuberculosis and chest diseases of a tertiary referral tuberculosis institute in New Delhi, India.

OBJECTIVE

To study the efficacy and safety of sparfloxacin, in combination with kanamycin (for the initial 3-4 months) and ethionamide, in multidrug-resistant (MDR) pulmonary tuberculosis patients.

DESIGN

Prospective, uncontrolled study of nine patients with pulmonary tuberculosis who had received adequate anti-tuberculosis treatment with first-line drugs, including supervised category II treatment regimen as per World Health Organization guidelines for 5 months, and were still sputum smear acid-fast bacilli positive. It was planned to give them kanamycin (initial 3-4 months), ethionamide and sparfloxacin for 2 years.

RESULTS

All nine patients achieved sputum conversion within 6 months. Seven patients converted within 3.5 months, two of these within 1 month. All patients reported improvement in clinical symptoms, and chest X-ray improved in seven patients. Four patients developed mild to moderate phototoxicity. Eight patients have completed treatment for an average of 19 months (range 15-24 months), and are still under follow-up. One patient defaulted after 7 months of treatment.

CONCLUSIONS

In MDR-TB patients, sparfloxacin, along with other anti-tuberculosis drugs, appears to be effective and safe. Mild to moderate phototoxicity is common. However, the long-term results, including relapses, are still awaited.

"Pot-lid" technique for aesthetic removal of small lipoma on the face

BACKGROUND

Patients presenting with an asymptomatic subcutaneous facial lipoma desire its removal in order to restore the contour of the face. The standard treatment for lipoma is excision, with the size of the incision being about one-half of that of the tumor itself. The long linear scar resulting from simple excision may fail to improve the appearance of the patient. The removal of the lipoma through a small incision or a punch hole decreases the size of the resulting scar, but does not eliminate it completely.

OBJECTIVE

To improve the aesthetic outcome of the commonly used technique for lipoma removal, known as the narrow hole extrusion technique (NHET), by modification.

METHODS

Four patients (three men and one woman) with small lipomas on the face (three on the forehead and one on the cheek) were selected for the procedure. A 5-mm punch was inserted deep into the center of the lesion to create a circular hole. The punched-out piece of skin was kept in normal saline. The lipoma was extruded with the help of a hemostat and by squeezing pressure. This resulted in the formation of a subcutaneous cavity. After achieving hemostasis, two absorbable buried subcutaneous sutures were placed to create support for the graft. The punched-out piece of skin was then positioned to cover the defect, like a "lid on a pot" and dressed.

RESULTS

The color and texture match of the graft with the surrounding skin were excellent in three of the four patients by the end of 6 months. The graft, which was depressed in the fourth patient, improved through spot dermabrasion.

CONCLUSION

The proposed modification of the NHET for lipoma removal improves the cosmetic outcome.

Spinal endoscopy in chronic low back pain with radiculopathy. A prospective case series

All 38 patients listed for day-case spinal endoscopy over a 12-month period (April 1998 - April 1999), who had chronic severe low back pain with a radiculopathic element, were studied prospectively. The mean [range] pain duration before treatment was 10.9 [2-26] years and 50% had failed back surgery syndrome. In all patients in whom treatment was completed (n = 34), the pain-generating nerve roots were located through symptom interaction with the patient. All had epidural scar tissue, 14 (41%) having dense adhesions. Mobilisation of adhesions around the nerve root (neuroplasty) was performed so that a pocket was formed for the subsequent placement of bupivacaine, Depomedrone and clonidine. No intra-operative complications occurred and side-effects were minimal. Follow-up over a 12-month period showed statistically significant reductions in pain scores and disability. Spinal endoscopy may be the diagnostic method of choice for epidural fibrosis. It has substantial therapeutic and research potential. Prospective randomised studies are required.

Stage-specific modulation of IFN-regulatory factor 4 function by Krüppel-type zinc finger proteins

Optimal humoral responses depend on the activation of Ag-specific B cells, followed by their progression toward a fully differentiated phenotype. Acquisition of stage-appropriate patterns of gene expression is crucial to this differentiation program. However, the molecular mechanisms used by B cells to modulate gene expression as they complete their maturation program are poorly understood. IFN-regulatory factor 4 (IRF-4) plays a critical role in mature B cell function. Using the transcriptional regulation of the human B cell activation marker CD23 as a model system, we have previously demonstrated that IRF-4 is induced in response to B cell-activating stimuli and that it acts as a transactivator of CD23 gene expression. We have furthermore found that IRF-4 function can be blocked by B cell lymphomas 6 (BCL-6) protein, a Krüppel-type zinc finger repressor normally expressed in germinal center B cells. However, CD23 expression is known to be down-regulated in plasma cells despite high level expression of IRF-4 and the lack of BCL-6, suggesting that in plasma cells the IRF-4-mediated induction of CD23 is prevented by its interaction with a distinct repressor. In this set of studies, we demonstrate that IRF-4 interacts with B lymphocyte-induced maturation protein/positive regulatory domain I-binding factor 1 (Blimp1/PRD1-BF1), a Krüppel-type zinc finger protein whose expression correlates with terminal B cell differentiation. Functional studies indicate that Blimp1, like BCL-6, can block IRF-4-transactivating ability. These findings thus support a model whereby IRF-4 function is modulated in a stage-specific manner by its interaction with developmentally restricted sets of Krüppel-type zinc finger proteins.

Down-regulation of cholesterol 7alpha-hydroxylase (CYP7A1) gene expression by bile acids in primary rat hepatocytes is mediated by the c-Jun N-terminal kinase pathway

Cholesterol 7alpha-hydroxylase (CYP7A1), the rate-limiting enzyme in the neutral pathway of bile acid biosynthesis, is feedback-inhibited at the transcriptional level by hydrophobic bile acids. Recent studies show that bile acids are physiological ligands for farnesoid X receptor (FXR). Activated FXR indirectly represses CYP7A1 transcription through induction of small heterodimer protein (SHP-1). In this study, we provide evidence that bile acids rapidly down-regulate CYP7A1 transcription via activation of the JNK/c-Jun pathway. Furthermore, we demonstrate that SHP-1 is also a direct target of activated c-Jun. In primary rat hepatocyte cultures, taurocholate (TCA) strongly activated JNK in a time- and concentration-dependent manner. Tumor necrosis factor-alpha, a potent activator of JNK, also rapidly activated JNK and down-regulated CYP7A1 mRNA levels. Overexpression of dominant-negative JNK1 or a transactivating domain mutant of c-Jun significantly blocked the ability of TCA to down-regulate CYP7A1 mRNA. In contrast, overexpression of wild-type c-Jun (c-Jun(wt)) enhanced the repression of CYP7A1 by TCA. Moreover, overexpression of c-Jun(wt) resulted in increased SHP-1 promoter activity. Mutation of a putative AP-1 (c-Jun) element suppressed c-Jun-mediated activation of the SHP-1 promoter construct. These results indicate that the bile acid-activated JNK pathway plays a pivotal role in regulating CYP7A1 levels in primary rat hepatocytes.

Involvement of Bcl-2 and Bax in photodynamic therapy-mediated apoptosis. Antisense Bcl-2 oligonucleotide sensitizes RIF 1 cells to photodynamic therapy apoptosis

Photodynamic therapy (PDT), a promising treatment modality, is an oxidative stress that induces apoptosis in many cancer cells in vitro and tumors in vivo. Understanding the mechanism(s) involved in PDT-mediated apoptosis may improve its therapeutic efficacy. Although studies suggest the involvement of multiple pathways, the triggering event(s) responsible for PDT-mediated apoptotic response is(are) not clear. To investigate the role of Bcl-2 in PDT-mediated apoptosis, we employed Bcl-2-antisense and -overexpression approaches in two cell types differing in their responses toward PDT apoptosis. In the first approach, we treated radiation-induced fibrosarcoma (RIF 1) cells, which are resistant to silicon phthalocyanine (Pc 4)-PDT apoptosis, with Bcl-2-antisense oligonucleotide. This treatment resulted in sensitization of RIF 1 cells to PDT-mediated apoptosis as demonstrated by i) cleavage of poly(ADP-ribose) polymerase, ii) DNA ladder formation, iii) terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells, and iv) DEVDase activity. This treatment also resulted in oligonucleotide concentration-dependent decrease in cell viability and down-regulation of Bcl-2 protein with a concomitant increase in apoptosis. However, the level of Bax, a pro-apoptotic member of Bcl-2 family, remained unaltered. In the second approach, an overexpression of Bcl-2 in PDT apoptosis-sensitive human epidermoid carcinoma (A431) cells resulted in enhanced apoptosis and up-regulation of Bax following PDT. In both the approaches, the increased Bax/Bcl-2 ratio was associated with an increased apoptotic response of PDT. Our data also demonstrated that PDT results in modulation of other Bcl-2 family members in a way that the overall ratio of pro-apoptotic and anti-apoptotic member proteins favors apoptosis.

Effects of intracerebroventricularly administered chimeric peptide of metenkephalin and FMRFa--[D-Ala2]YFa-on antinociception and its modulation in mice

An enzymatically stable analog of YGGFMKKKFMRFamide (YFa), a chimeric peptide of metenkephalin and FMRFa, was synthesised. The antinociceptive effects of intracerebroventricular injections of this analog-[D-Ala2)]YAGFMKKKFMRFamide ([D-Ala2]YFa)-was then investigated using the mouse radiant-heat tail-flick test. [D-Ala2]YFa produced modest to good antinociception at 1, 2, and 5 microg/mouse (0.64, 1.28, and 3.22 nmol, respectively). This antinociceptive effect was completely reversed by the opioid receptor antagonist naloxone (1.5 microg/mouse: 4.12 nmol, intracerebroventricular [i.c.v.]), administered 5 min prior. Pretreatment (5 min) with either neuropeptides FF (1 microg/mouse: 0.92 nmol, i.c.v.) or FMRFa (1 microg/mouse: 1.69 nmol, i.c.v.) significantly attenuated the antinociceptive effects induced by [D-Ala2]YFa (1 microg/mouse, i.c.v.). Intracerebroventricular administration of [D-Ala2]YFa at 1 microg/mouse dose with morphine (2 microg/mouse: 5.86 nmol, i.c.v.) produced an additive antinociceptive effect, suggesting that [D-Ala2]YFa may have a modulatory effect on opioid (morphine) analgesia. These results provide further support for a role of such amphiactive sequences in antinociception and its modulation.

Mapping of hiv-1 Gag epitopes recognized by polyclonal antibodies using gene-fragment phage display system

Phage display has emerged as a powerful technique for mapping epitopes recognised by monoclonal and polyclonal antibodies. We have recently developed a simple gene-fragment phage display system and have shown its utility in mapping epitope recognised by a monoclonal antibody. In the present study, we have employed this system in mapping epitopes recognised by polyclonal antibodies raised against HIV-1 capsid protein, p24 which is derived from proteolytic cleavage of Gag polyprotein. HIV-1 gag DNA was fragmented by DNase I and the fragments (50-250 bp) were cloned into gene-fragment phage display vector to construct a library of phages displaying peptides. This phage library was used for affinity selection of phages displaying epitopes recognised by rabbit anti-p24 polyclonal antibodies. Selected phages contained sequences from two discrete regions of p24, demonstrating the presence of two antigenic regions. The DNA sequences encoding these regions were also cloned and expressed as GST fusion proteins. The immunoreactivity of these epitopes as GST fusion proteins, or as phage-displayed peptides, was comparable in ELISA system using same anti-p24 polyclonal antibodies. The results indicate that the gene-fragment based phage display system can be used efficiently to identify epitopes recognised by polyclonal antibodies, and phage displayed epitopes can be directly employed in ELISA to detect antibodies.

Effects of intracerebroventricularly administered chimeric peptide of metenkephalin and FMRFa--[D-Ala2]YFa-on antinociception and its modulation in mice

An enzymatically stable analog of YGGFMKKKFMRFamide (YFa), a chimeric peptide of metenkephalin and FMRFa, was synthesised. The antinociceptive effects of intracerebroventricular injections of this analog-[D-Ala2)]YAGFMKKKFMRFamide ([D-Ala2]YFa)-was then investigated using the mouse radiant-heat tail-flick test. [D-Ala2]YFa produced modest to good antinociception at 1, 2, and 5 microg/mouse (0.64, 1.28, and 3.22 nmol, respectively). This antinociceptive effect was completely reversed by the opioid receptor antagonist naloxone (1.5 microg/mouse: 4.12 nmol, intracerebroventricular [i.c.v.]), administered 5 min prior. Pretreatment (5 min) with either neuropeptides FF (1 microg/mouse: 0.92 nmol, i.c.v.) or FMRFa (1 microg/mouse: 1.69 nmol, i.c.v.) significantly attenuated the antinociceptive effects induced by [D-Ala2]YFa (1 microg/mouse, i.c.v.). Intracerebroventricular administration of [D-Ala2]YFa at 1 microg/mouse dose with morphine (2 microg/mouse: 5.86 nmol, i.c.v.) produced an additive antinociceptive effect, suggesting that [D-Ala2]YFa may have a modulatory effect on opioid (morphine) analgesia. These results provide further support for a role of such amphiactive sequences in antinociception and its modulation.

Genetic toxicology of a paradoxical human carcinogen, arsenic: a review

Arsenic is widely distributed in nature in air, water and soil in the form of either metalloids or chemical compounds. It is used commercially, as pesticide, wood preservative, in the manufacture of glass, paper and semiconductors. Epidemiological and clinical studies indicate that arsenic is a paradoxical human carcinogen that does not easily induce cancer in animal models. It is one of the toxic compounds known in the environment. Intermittent incidents of arsenic contamination in ground water have been reported from several parts of the world. Arsenic containing drinking water has been associated with a variety of skin and internal organ cancers. The wide human exposure to this compound through drinking water throughout the world causes great concern for human health. In the present review, we have attempted to evaluate and update the mutagenic and genotoxic effects of arsenic and its compounds based on available literature.

Blunt abdominal trauma with delayed rupture of splenic haematoma in a haemophiliac patient

A 13-year-old haemophilia A patient presented with pain in the abdomen, 4 days after a blunt abdominal trauma. The computed tomography scan of the abdomen showed a large splenic haematoma. The patient was initially managed with factor VIII replacement therapy, but 4 weeks later he had a delayed rupture of the splenic haematoma with haemoperitoneum and shock. An elective splenectomy under factor VIII therapy was successfully performed.

Sustained-release bupropion for selective serotonin reuptake inhibitor-induced sexual dysfunction: a randomized, double-blind, placebo-controlled, parallel-group study

OBJECTIVE

The authors compared low-dose sustained-release bupropion with placebo for sexual dysfunction induced by selective serotonin reuptake inhibitors (SSRIs).

METHOD

Thirty adults who had received SSRIs for at least 6 weeks, who were euthymic, and who had sexual dysfunction as determined by a total score greater than 19 out of a possible 30 on the Arizona Sexual Experience Scale were randomly assigned to receive either 150 mg/day of sustained-release bupropion or placebo at 6:00 p.m. for 3 weeks.

RESULTS

There were no significant differences between the sustained-release bupropion and placebo groups as measured by change in Arizona Sexual Experiences Scale or Hamilton Depression Rating Scale scores or side effects.

CONCLUSIONS

Future studies should compare higher doses of bupropion for treating sexual dysfunction and should include a greater number of subjects.

Intralesional cryosurgery using lumbar puncture and/or hypodermic needles for large, bulky, recalcitrant keloids

BACKGROUND

Keloids are notoriously difficult to treat. A variety of treatment modalities are currently in use, indicating that none is totally satisfactory. Surface cryosurgery is effective for smaller keloids, but not for larger ones. It often results in widespread depigmentation over the surface of the keloids, which may not be desirable, especially in patients with dark skin.

OBJECTIVES

To determine the efficacy of intralesional (IL) cryosurgery in large, bulky keloids unresponsive to IL steroids, and to observe the extent of depigmentation and other complications produced by the technique.

METHODS

Twelve patients with large, bulky, symptomatic keloids unresponsive to at least five injections of IL triamcinolone acetonide were included in the study. The age of the patients and the duration of the keloids were in the range 19-50 years and 1-12 years, respectively. The IL cryosurgery device was assembled using a small liquid nitrogen Dewar cylinder, a rubber and a plastic tube taken from a drip-set, adhesive tape, and hypodermic and lumbar puncture needles. The lumbar puncture or injection needle was introduced through the lesion until it appeared at the other side. Liquid nitrogen was then passed through the needle. The freezing time was between 20 and 30 s. The procedure was repeated for a second freeze-thaw cycle in the same session.

RESULTS

The patients underwent a minimum of five up to a maximum of 10 sessions of IL cryosurgery. Seven out of 12 patients showed > 75% flattening. Depigmentation was observed along the tracks of the needles in all the patients, which improved during follow-up due to pigment spread from the normally pigmented areas in between. At the end of follow-up, 1-25% of the area remained hypo- or depigmented in four patients, 26-50% in six patients, and 51-75% in the remaining two patients.

CONCLUSIONS

IL cryosurgery should be the preferred mode of therapy for large, bulky keloids, which are unresponsive to IL steroids.

Effect of 2',4'-dichlorobenzamil hydrochloride, a Na(+)-Ca(2+) exchange inhibitor, on human spermatozoa

The present study is aimed to investigate the contact spermicidal efficacy of 2',4'-dichlorobenzamil hydrochloride (DBZ), a Na(+)-Ca(2+) exchange inhibitor, on ejaculated human spermatozoa. The drug produced a dose- and time-dependent spermicidal action on human spermatozoa. A concentration of 4 mM produced total loss of sperm viability within 1 min of addition to total semen. On the other hand, a similar action on spermatozoa separated from semen was noted at 0.5 mM concentration. The loss of spermatozoal viability was accompanied with an increase in intracellular Ca(2+). Sperm revival testing with glucose suggested a spermicidal rather than a spermiostatic action.