A straightforward approach for bioorthogonal labeling of proteins and organelles in live mammalian cells, using a short peptide tag

Background

In the high-resolution microscopy era, genetic code expansion (GCE)-based bioorthogonal labeling offers an elegant way for direct labeling of proteins in live cells with fluorescent dyes. This labeling approach is currently not broadly used in live-cell applications, partly because it needs to be adjusted to the specific protein under study.

Results

We present a generic, 14-residue long, N-terminal tag for GCE-based labeling of proteins in live mammalian cells. Using this tag, we generated a library of GCE-based organelle markers, demonstrating the applicability of the tag for labeling a plethora of proteins and organelles. Finally, we show that the HA epitope, used as a backbone in our tag, may be substituted with other epitopes and, in some cases, can be completely removed, reducing the tag length to 5 residues.

Conclusions

The GCE-tag presented here offers a powerful, easy-to-implement tool for live-cell labeling of cellular proteins with small and bright probes.

Resolving ESCRT-III Spirals at the Intercellular Bridge of Dividing Cells Using 3D STORM

The ESCRT machinery mediates membrane fission in a variety of processes in cells. According to current models, ESCRT-III proteins drive membrane fission by assembling into helical filaments on membranes. Here, we used 3D STORM imaging of endogenous ESCRT-III component IST1 to reveal the evolution of the structural organization of ESCRT-III in mammalian cytokinetic abscission. Using this approach, ESCRT-III ring and spiral assemblies were resolved and characterized at different stages of abscission. Visualization of IST1 structures in cells lacking the microtubule-severing enzyme spastin and in cells depleted of specific ESCRT-III components or the ATPase VPS4 demonstrated the contribution of these components to the organization and function of ESCRTs in cells. This work provides direct evidence that ESCRT-III proteins form helical filaments to mediate their function in cells and raises new mechanistic scenarios for ESCRT-driven cytokinetic abscission.

Direct fluorescent-dye labeling of α-tubulin in mammalian cells for live cell and superresolution imaging

This work describes an elegant approach for direct, site-specific labeling of proteins with fluorescent-dyes for live cell imaging. By integrating a noncanonical amino acid that is capable of binding a fluorescent dye into tubulin, we directly and specifically labeled tubulin with a fluorescent-dye and imaged microtubules in live mammlian cells.

Genetic code expansion and bioorthogonal labeling provide for the first time a way for direct, site-specific labeling of proteins with fluorescent-dyes in live cells. Although the small size and superb photophysical parameters of fluorescent-dyes offer unique advantages for high-resolution microscopy, this approach has yet to be embraced as a tool in live cell imaging. Here we evaluated the feasibility of this approach by applying it for α-tubulin labeling. After a series of calibrations, we site-specifically labeled α-tubulin with silicon rhodamine (SiR) in live mammalian cells in an efficient and robust manner. SiR-labeled tubulin successfully incorporated into endogenous microtubules at high density, enabling video recording of microtubule dynamics in interphase and mitotic cells. Applying this labeling approach to structured illumination microscopy resulted in an increase in resolution, highlighting the advantages in using a smaller, brighter tag. Therefore, using our optimized assay, genetic code expansion provides an attractive tool for labeling proteins with a minimal, bright tag in quantitative high-resolution imaging.

Auctions with Severely Bounded Communication

We study auctions with severe bounds on the communication allowed: each bidder may only transmit t bits of information to the auctioneer. We consider both welfare- and profit-maximizing auctions under this communication restriction. For both measures, we determine the optimal auction and show that the loss incurred relative to unconstrained auctions is mild. We prove non-surprising properties of these kinds of auctions, e.g., that in optimal mechanisms bidders simply report the interval in which their valuation lies in, as well as some surprising properties, e.g., that asymmetric auctions are better than symmetric ones and that multi-round auctions reduce the communication complexity only by a linear factor.

Some puzzling situations in the onset, occurrence and future of coronary heart disease in developed and developing populations, particularly such in sub-Saharan Africa

Coronary heart disease (CHD) was rare in developed populations until the early 1900s; this prevailed even among the small segments who were prosperous and who, in measure, had most of the currently recognised risk factors. However, in the 1930s, with improved circumstances from general rises in socio-economic state, there were major increases in the occurrence and mortality rate from the disease, the latter reaching a third of the total mortality in some countries, as in the United Kingdom (UK). Puzzlingly, the inter-population diversity of the increases in CHD has been such that there are as much as five fold differences in CHD mortality rates, as, for example, between Poland and Spain. Within recent years, with appropriate treatments, the mortality rate has halved in some countries, again, as in the UK. However, the incidence rate of the disease has diminished little or hardly at all. Risk factors include a familial component and, nutritionally, over-eating, a high fat intake, relatively low intakes of plant foods, especially of vegetables and fruit and, non-nutritionally, smoking, excessive alcohol consumption and a low level of everyday physical activity. On the one hand, known risk factors, broadly, are considered to be capable of explaining only about half of the variation in the occurrence of the disease. Even at present, known risk factors far from fully explain the epidemiological differences in mortality rates. Yet, on the other hand, there is abundant evidence that in population groups, among whom risk factors are low or have been reduced, CHD incidence and mortality rates are lower. Notwithstanding this knowledge, broadly, there is very little interest in the general public in taking avoiding measures. As to the situation in developing populations, in sub-Saharan Africa, in urban Africans, as in Johannesburg, South Africa, despite considerable westernisation of life style and with rises in risk factors, CHD remains of very low occurrence, the situation thereby resembling, historically, its relatively slow emergence in developed populations. In most eastern countries, mortality rates remain relatively low, as in Russia and Japan. However, in major contrast, in India, rates have risen considerably in urban dwellers. Indeed, in Indian immigrants, as in those in the UK, their rate actually exceeds that in the country's white population. In brief, much remains to be explained in the epidemiology of the disease.

Major differences in the IgG subclass response to Helicobacter pylori in the first and third worlds

BACKGROUND

Studies in developed countries would suggest that the immune response to Helicobacter pylori infection is a T helper cell I predominant response. Unlike subjects from developed countries, those resident in developing countries are subject to infection with a myriad of gastrointestinal pathogens from early in life. Given that H. pylori is acquired early in life, such infections may alter the immune response to H. pylori. The aim of this study was to compare the immune response to H. pylori in subjects from developed and developing countries.

METHODS

Using a previously validated IgG subclass ELISA, the H. pylori specific IgG I/IgG2 subclass ratio (a marker of the T helper cell response) in 58 adult and 21 paediatric symptomatic H. pylori positive Sowetan subjects was compared with that in 64 Australian and 45 German symptomatic H. pylori positive subjects.

RESULTS

An IgGI predominant response (IgG1/IgG2 ratio >1) was observed in 81% of Sowetan adults and 90% of children compared with 4.7% of Australians and 4.4% of Germans. The IgG1/IgG2 ratio was significantly higher in Sowetans compared with Australians and Germans (P < 0.001). In Australian and German subjects the IgG1/IgG2 ratio was significantly higher in NUD compared with DU. No significant difference was observed between NUD and other disease states in Sowetans.

CONCLUSIONS

This study is the first to provide evidence that the host immune response to H. pylori infection in an African population differs to that observed in subjects from developed countries. Further studies are required to determine if this occurs in other developing countries.

Colorectal cancer in an African city population in transition

An enquiry has been made on a series of African patients with colorectal cancer who were admitted in 1995-1999 to Chris Hani Baragwanath Hospital (3200 beds), and who lived in Soweto (population about 1 million), Johannesburg, South Africa. In the urban context described, Africans have considerably more advantages, socio-economically, dietarily and in other respects, than their rural counterparts. The 126 patients comprised 58 males and 68 females, giving calculated incidence rates in their communities for colorectal cancer of 1.7 and 2.0, respectively, per 100,000 'world' population. In contrast, as indicated in the South African Cancer Registry for 1993-1995, the corresponding rates for white males and females were 24.7 and 19.3, respectively, per 100,000. The proportion of African patients under 40 years was 19.0%; but was only 4.0% in the white population. In contrast to this major disparity, there was only a minor interethnic disparity regarding cancers that are very common in Africans, namely, those of the oesophagus and lung. Hence, with ongoing transitional changes - in diet and other respects - the relatively high proportion of younger African patients probably indicates a rising occurrence of colorectal cancer in the urban African population.

Gastric cancer in sub-Saharan Africa

Gastric cancer has a variable but generally low prevalence in black populations of sub-Saharan Africa, despite a high prevalence of Helicobacter pylori (the 'African enigma'). Evidence from Soweto indicates that the host response to H. pylori may be protective against a virulent organism and that, in most people, H. pylori does not lead to more serious sequelae. This suggests that there may be host protective/inhibitory factors present, which prevent the progression of H. pylori-induced chronic active gastritis to cancer.

Tropical enteropathy: a T-cell-mediated crypt hyperplastic enteropathy

OBJECTIVE

Tropical enteropathy is widespread throughout the tropics, but its pathogenesis is unknown. T-cell activation has been demonstrated to result in enteropathy in vitro and in animal models, and occurs in untreated patients with coeliac disease. We have therefore examined the hypothesis that T-cell activation is important in the pathogenesis of tropical enteropathy.

PATIENTS AND METHODS

Healthy black Zambian subjects were compared with black and white South Africans. Quantitative microscopy was conducted on distal duodenal biopsies. Mucosal T-cell activation was quantitated by dual colour immunofluorescence staining for CD3 plus CD69 or HLA-DR. Crypt proliferation was measured by direct counting of Feulgen-stained mitotic figures, and systemic immune activation by assay of serum tumour necrosis factor alpha (TNF-alpha).

RESULTS

Villous height was reduced (P = 0.0004), crypt depth increased (P < 0.0001), and mitoses per crypt increased (P = 0.014) in black Zambians compared with black and white South Africans. Mucosal thickness was similar. Intraepithelial lymphocyte count was increased in the black groups compared with whites (P = 0.03). CD3+CD69+ (P = 0.0007) and CD3+HLA-DR+ (P < 0.0001) expression was increased in black Zambians compared with black and white South Africans. Serum TNF-alpha was similar in all groups.

CONCLUSIONS

Tropical enteropathy is associated with mucosal T-cell activation and crypt hyperplasia. Tropical enteropathy occurs in the absence of malnutrition, diarrhoea or systemic illness.

Helicobacter pylori--an African perspective

Helicobacter pylori is ubiquitous in Africa, with acquisition in childhood the rule. Despite the prevalence of a virulent strain (in Soweto, most H. pylori organisms are cagA- and vacAS(1)-positive) H. pylori-associated pathology (duodenal ulcer, gastric ulcer and gastric cancer) has a variable, often low distribution in sub-Saharan Africa that does not parallel H. pylori prevalence in the population, suggesting a different natural history from that seen in developed countries. Progression to atrophic gastritis in Africans does not appear to differ from that reported in other regions, but as yet unidentified factors may play a role in inhibiting progression to gastric cancer. Studies have suggested that the specific IgG subclass response to H. pylori is predominately IgG1 (suggestive of a Th2 response), and the Th2 response may provide a protective effect against development of gastric cancer. Host immune mechanisms may be the key to different responses to H. pylori in the developed and developing worlds.

The gastro-oesophageal reflux disease complex in sub-Saharan Africa

Epidemiological and clinical studies that have reported on gastro-oesophageal reflux disease (GERD), Barrett's oesophagus, oesophageal adenocarcinoma and Helicobacter pylori infection in sub-Saharan Africa were reviewed. The data indicate that Barrett's oesophagus is rare and oesophageal adenocarcinoma uncommon in all regions of sub-Saharan Africa studied (South Africa, Ethiopia, Nigeria, Zimbabwe, Kenya and Uganda). Hiatus hernia is also uncommon. There are too few reports of GERD to allow comment. The overwhelming majority of oesophageal cancers are squamous cell type. H. pylori infection is ubiquitous with an overall prevalence of 61-100%. It is concluded that although urbanization has resulted in an increase of risk factors associated with GERD, which would be expected to lead to an increase in this disease among Africans, this increase has not happened. It is believed that the critical factor preventing GERD in black Africans is H. pylori infection, which is usually acquired in childhood, is lifelong and is probably protective for the oesophagus.

Sequential inactivation of rdxA (HP0954) and frxA (HP0642) nitroreductase genes causes moderate and high-level metronidazole resistance in Helicobacter pylori

Helicobacter pylori is a human-pathogenic bacterial species that is subdivided geographically, with different genotypes predominating in different parts of the world. Here we test and extend an earlier conclusion that metronidazole (Mtz) resistance is due to mutation in rdxA (HP0954), which encodes a nitroreductase that converts Mtz from prodrug to bactericidal agent. We found that (i) rdxA genes PCR amplified from 50 representative Mtz(r) strains from previously unstudied populations in Asia, South Africa, Europe, and the Americas could, in each case, transform Mtz(s) H. pylori to Mtz(r); (ii) Mtz(r) mutant derivatives of a cultured Mtz(s) strain resulted from mutation in rdxA; and (iii) transformation of Mtz(s) strains with rdxA-null alleles usually resulted in moderate level Mtz resistance (16 microg/ml). However, resistance to higher Mtz levels was common among clinical isolates, a result that implicates at least one additional gene. Expression in Escherichia coli of frxA (HP0642; flavin oxidoreductase), an rdxA paralog, made this normally resistant species Mtz(s), and frxA inactivation enhanced Mtz resistance in rdxA-deficient cells but had little effect on the Mtz susceptibility of rdxA(+) cells. Strains carrying frxA-null and rdxA-null alleles could mutate to even higher resistance, a result implicating one or more additional genes in residual Mtz susceptibility and hyperresistance. We conclude that most Mtz resistance in H. pylori depends on rdxA inactivation, that mutations in frxA can enhance resistance, and that genes that confer Mtz resistance without rdxA inactivation are rare or nonexistent in H. pylori populations.

Pancreatitis in Soweto, South Africa. Focus on alcohol-related disease

Both acute pancreatitis and chronic pancreatitis now appear to be endemic at Soweto, South Africa, and they carry a substantial toll in terms of morbidity and mortality. Case-control studies identified the same three environmental factors in each disease, namely, heavy alcohol consumption, marked exposure to occupational chemicals and low intake of fruit (a major source of vitamin C). This congruity, and parallel trends on blood biochemical analysis indicating heightened free radical activity coupled with poor antioxidant status, suggest that the two diseases may be part of a pathobiological spectrum that is linked by pancreatic oxidant stress. Further, asymptomatic chronic alcoholics had plasma glutathione concentrations that were midway between the values in non-alcoholic controls and patients with chronic pancreatitis, being significantly different from each. And, finally, apparently healthy Sowetans were actually in a state of oxidant stress that was tied in with their very poor vitamin C status, and lower serum selenium concentrations than in the UK. These data, and evidence that both antioxidants mitigate against alcoholic toxicity in experimental studies, may offer scope for disease prophylaxis in this unprivileged community.

Differences in genotypes of Helicobacter pylori from different human populations

DNA motifs at several informative loci in more than 500 strains of Helicobacter pylori from five continents were studied by PCR and sequencing to gain insights into the evolution of this gastric pathogen. Five types of deletion, insertion, and substitution motifs were found at the right end of the H. pylori cag pathogenicity island. Of the three most common motifs, type I predominated in Spaniards, native Peruvians, and Guatemalan Ladinos (mixed Amerindian-European ancestry) and also in native Africans and U.S. residents; type II predominated among Japanese and Chinese; and type III predominated in Indians from Calcutta. Sequences in the cagA gene and in vacAm1 type alleles of the vacuolating cytotoxin gene (vacA) of strains from native Peruvians were also more like those from Spaniards than those from Asians. These indications of relatedness of Latin American and Spanish strains, despite the closer genetic relatedness of Amerindian and Asian people themselves, lead us to suggest that H. pylori may have been brought to the New World by European conquerors and colonists about 500 years ago. This thinking, in turn, suggests that H. pylori infection might have become widespread in people quite recently in human evolution.

Fermentation of dietary starch in humans

OBJECTIVE

Dietary starch that escapes digestion in the small intestine may be quantitatively more important than dietary fiber as a substrate for fermentation. The products of fermentation have important implications in the pathogenesis of colorectal cancer and other diseases of the large bowel, which are uncommon in Africans but have a high prevalence in Western populations.

METHODS

Maize porridge is a staple of most blacks in South Africa. Stale maize porridge (high-resistant starch [HRS]) seems to induce greater fermentation in the large bowel than fresh maize porridge (low-resistant starch [LRS]).

RESULTS

In the present study, healthy colostomy subjects fed stale maize porridge had significantly more production of short-chain fatty acids (SCFA) (mean SCFA, HRS = 182.6; mean SCFA, LRS = 116.1; p < 0.05) in their colostomy effluent together with a significant drop in stool pH (mean pH, HRS = 5.91; mean pH, LRS = 6.70; p < 0.001). The SCFA butyrate (mean, HRS = 35.1; mean, LRS = 17.6; p < 0.05) and acetate (mean, HRS = 93.9; mean, LRS = 65.8; p < 0.05) were significantly elevated on the stale maize porridge diet when compared with consumption of fresh maize porridge. SCFA propionate (mean, HRS = 43.1; mean, LRS = 24.8; p = 0.05), also increased with stale maize porridge, but was not statistically significant.

CONCLUSION

A high-resistant starch diet and its resultant increase in fermentation products may be partly responsible for protecting the black population against colorectal cancers and other large bowel diseases.

Dendritic spine formation and pruning: common cellular mechanisms?

The recent advent of novel high-resolution imaging methods has created a flurry of exciting observations that address a century-old question: what are biological signals that regulate formation and elimination of dendritic spines? Contrary to the traditional belief that the spine is a stable storage site of long-term neuronal memory, the emerging picture is of a dynamic structure that can undergo fast morphological variations. Recent conflicting reports on the regulation of spine morphology lead to the proposal of a unifying hypothesis for a common mechanism involving changes in postsynaptic intracellular Ca2+ concentration, [Ca2+]i: a moderate rise in [Ca2+]i causes elongation of dendritic spines, while a very large increase in [Ca2+]i causes fast shrinkage and eventual collapse of spines. This hypothesis provides a parsimonious explanation for conflicting reports on activity-dependent changes in dendritic spine morphology, and might link these changes to functional plasticity in central neurons.

Temporal analysis of connexin43 protein and gene expression throughout the menstrual cycle in human endometrium

OBJECTIVE

To analyze the pattern of connexin43 gene and protein expression in human endometrium throughout the menstrual cycle.

DESIGN

Controlled clinical study.

SETTING

An academic research center.

PATIENT(S)

Women with 28-day menstrual cycles who had mechanical infertility and failed to conceive after IVF treatment.

INTERVENTION(S)

Endometrial and blood samples were collected on days 8, 12, 14, 21, and 25 of spontaneous menstrual cycles.

MAIN OUTCOME MEASURE(S)

Endometrial expression of connexin43 protein and messenger RNA, endometrial thickness, and serum concentrations of gonadotropins and steroids.

RESULT(S)

The expression of connexin43 gene and protein decreased on day 12 and day 14 of the menstrual cycle and then increased on day 21 and day 25, respectively. A serum LH surge accompanied by a peak in the FSH concentration was observed on days 12-14. The progesterone concentration increased on days 21-25, but there was no significant change in the E2 concentration. The thickness of the endometrium increased between days 8 and 12 and did not change further between days 21 and 25.

CONCLUSION(S)

The expression of connexin43 gene and protein in human endometrium changes during the menstrual cycle in a pattern that is associated with the secretion of LH, FSH, and progesterone. This pattern may serve as a marker for implantation competence.

Case Control Study of Environmental Factors in the Etiology of the First Attack of Acute Pancreatitis: A Pilot Study

The aim of this case control study was to assess environmental factors in the etiology of the first attack of acute pancreatitis (AP) in Soweto, South Africa, in the light of modern developments. The study group consisted of 30 patients presenting with a first attack of AP, and 30 healthy age- and gender-matched controls. Fruit intake was found to be a protective factor (odds ratio [OR] 5.3). Crude ORs, although of marginal importance, showed that daily alcohol intake and years of exposure to occupational chemicals may be of significance but would require a much larger study to test these factors. This would be necessary in order to explain the rapid increase in pancreatitis coincident with urbanization and industrialization in the community.

Hepatitis B and C virus infections and liver function in AIDS patients at Chris Hani Baragwanath Hospital, Johannesburg

BACKGROUND

Impaired liver function tests and co-infection with hepatitis viruses in AIDS patients are common in western countries.

OBJECTIVE

To assess liver function and prevalence of co-infection with hepatitis B and hepatitis C viruses in AIDS patients at Chris Hani Baragwanath Hospital.

DESIGN

A prospective study.

SETTING

Chris Hani Baragwanath Hospital, Johannesburg, South Africa.

PATIENTS

One hundred consecutive patients with AIDS admitted to Chris Hani Baragwanath Hospital.

RESULTS

There were 52 males and 48 females aged 16 to 54 years (mean + SD: 34.6 + 7.5 years). The results of laboratory test were as follows: LFTs: bilirubin 11.8 (+15.6) mumol/l; AST: 79.6 (+/- 116.6) iu/L; alkaline phosphatase: 204.3 (+/- 237.4) i mu/L; albumin: 23.9 (+/- 6.2) g/l; CD4+ lymphocytes: 141.5 (+/- 168.6) microliters; CD8+: 666.9 (+/- 618.3) microliters; HBV - HbsAg: 6 (6%); HbsAg + eAg: 3 (3%); previous disease (Anti HBs and/or anti HBc): 35%, HCV: 1(1%).

CONCLUSION

Liver function tests were impaired in the majority of patients with AIDS (93%) in our setting. Evidence of previous and present HBV infection was present in 41%. This is different from what is observed in western countries (90-95%). The results also suggest that patients here acquired HBV infection while still immuno competent. HCV infection was rare.

Iron overload in Sub-Saharan Africa: to what extent is it a public health problem?

Excessive deposition of Fe in the organs and tissues of Sub-Saharan Africans was first described in South Africa in 1929. Fe overload, or siderosis, was initially attributed to infections and to metallic poisoning (Cu, Sn, Zn), and then to malnutrition. In 1953 it was hypothesized that it was due primarily to excessive Fe intake derived from foods and drinks prepared in Fe vessels. Recently, in 1992 it was advanced that a gene distinct from any HLA-linked locus may also play a role. As to sequelae, in early research on series of hospital patients, the condition was linked to scurvy, osteoporosis, diabetes, cirrhosis, and latterly, to hepatocellular cancer and tuberculosis. Accordingly, many have concluded that Fe overload is responsible for considerable morbidity and mortality, that adventitious Fe intake should be reduced, and that phlebotomy be recommended for those severely affected. However, there are numerous limitations in the evidence. There are also problems in interpretation, since levels of Fe in the serum are affected additionally by a variety of factors: infection, inflammation, certain cancers and alcohol intake. These considerations complicate attempts to assess to what extent the associations described denote causation, and whether Fe overload has significant ramifications for ill in the general African population. While the adverse sequelae of overload may be less of significance than many believe, the precise pathogenicity of the phenomenon will remain uncertain until further investigations, including prospective studies, are undertaken.

Rarity of colorectal adenomas in the African black population

In South African blacks colorectal cancers are uncommon and adenomatous polyps are rare, despite major changes in diet and lifestyle in the large urbanized community of Soweto (population over 3 million). Factors favouring adenomas formation are changes in bowel function. Thus, stool weights, defaecation frequencies, oro-caecal transit times and whole-gut transit times in Sowetans approximate those of western populations. Moreover a measure of westernization of diet has occurred, the salient feature being a greatly reduced fibre intake (14 g daily). Factors thought to inhibit adenoma formation are physiological malabsorption of maize, lactose and fructose. Sucrose activity is significantly lowered compared with whites. With regard to diet, fat consumption is well below that of western societies. There are differences in colon cell proliferation, faecal short chain fatty acids, faecal pH and colonic microflora compared with white groups. Equivocal factors that may be involved in adenoma formation are time trends and genetic background. In the context of the above it is apparent that in South African blacks inhibiting factors outweigh promotive factors in adenoma formation.

Is hydrosalpinx fluid cytotoxic?

Accumulation of oviductal fluid in the ampullar lumen as a result of occlusion of the infundibulum is referred to as hydrosalpinx. A low pregnancy rate (10%) after in-vitro fertilization (IVF) in hydrosalpinx patients and a relatively high incidence (50%) of abortions during the first trimester suggested that leakage of this fluid into the uterine cavity may exert a cytotoxic effect on the developing embryo. To examine this possibility, we analysed the composition of the hydrosalpinx fluid and tested its effect on human granulosa cells and embryos. Hydrosalpinx fluids and granulosa cells were collected from IVF patients at ovum pick-up. IVF eggs containing three pronuclei (3PN) were employed for this study. Analysis of hydrosalpinx fluids revealed electrolyte concentrations similar to those in serum with lower amounts of total protein and albumin. No blood cells were detected and bacterial cultures were negative. Granulosa cells incubated in hydrosalpinx fluid-containing medium (diluted 1:1) were not morphologically different and showed a steroidogenic capacity that was higher than that of cells incubated in its absence. Fertilized 3PN eggs incubated in IVF culture medium successfully developed into 6- to 8- and 8- to 16-cell embryos within 48 and 72 h, respectively. This rate of embryonal development was not impaired by hydrosalpinx fluid (at either 50 or 100% concentration). In the absence of a demonstrable detrimental effect we suggest that the low implantation rate in hydrosalpinx IVF patients may not be due to an embryotoxic effect. We further suggest that constant passage of fluid into the uterine cavity in these patients could possibly introduce some mechanical interference that may result in implantation failure.

Health/ill-health transition in less privileged populations: what does the future hold?

Changes in health/ill-health in response to alterations in environmental factors are recognised. While the phenomenon has been extensively investigated in Western populations, the extent and sequelae of transitions in less privileged populations are less well appreciated. Examples of changes are given, first for Western populations as a comparison but, more particularly, for rural and urban Africans, for African-Americans, and also for Australian Aboriginals, whose mortality rates for chronic degenerative diseases now exceed those of white Australians. Discussion of the likely future of these populations indicates that a lessening of proneness to Western diseases is unlikely.

Acute pancreatitis in Sowetan Africans. A disease with high mortality and morbidity

CONCLUSION

In African blacks, acute pancreatitis requiring hospital admission is a severe disease associated with a high mortality and significant long-term morbidity in surviving patients.

BACKGROUND

It has been suggested that acute pancreatitis has a benign course in Africans in contrast to Western populations. The aim of the present study was to ascertain the incidence of acute pancreatitis at Baragwanath Hospital for a 1-yr period and to test the validity of the above hypothesis.

METHODS

One hundred thirty-six patients with acute pancreatitis were retrospectively assessed. Fifty patients were available for a prospective follow-up examination and underwent sonographic and biochemical investigations. Acute pancreatitis was diagnosed if the patient presented with the typical clinical picture and a raised serum amylase level > 800 U/L.

RESULTS

The study consisted of 108 male and 28 female patients. Alcohol was identified as the predominant etiologic factor in 83.1%, biliary disease in 7.4%, and idiopathic causes in 6.6%. Substantial morbidity was encountered in 32.3% and was caused mainly by pancreatic complications, metabolic derangements, alcohol-related symptoms, and respiratory impairment. A portion (10.3%) of the patients developed further pancreatic pathology, such as pseudocysts, necroses, or an abscess. The overall mortality rate was 8.1%. Patients who died had a higher mean serum amylase, and most deaths occurred within 2 d of admission. Prospective follow-up after an average of 9.3 mo revealed serious morbidity in two-thirds of patients. Fifty-two percent suffered from severe abdominal pain, 36% complained of weight loss, and 18% were shown to have a sonographically abnormal pancreas. Fecal chymotrypsin levels indicated exocrine pancreatic impairment in 30.6%.

Effects of transition on bowel diseases in sub-Saharan Africans

In populations in sub-Saharan Africa, transitional changes in patterns of morbidity and mortality are taking place, with decreases in the diseases of poverty and infection, but rises in chronic diseases of prosperity, associated, however, with greater longevity. Remarkably, bowel diseases - appendicitis, diverticular disease, colon cancer - while nearly absent in rural areas, have very low incidences in urban dwellers, despite rises in risk factors, including a decreasing intake of fibre-containing foods. Currently, there is no explanation for the phenomenon, which stands in marked contrast to the considerable rises which have occurred in dental caries, obesity in women and diabetes.

Efficacy and tolerability of pantoprazole 40 mg versus 80 mg in patients with reflux oesophagitis

BACKGROUND

Pantoprazole is a substituted benzimidazole which is a potent inhibitor of gastric acid secretion by its action upon H+, K+-ATPase.

METHODS

Pantoprazole 40 mg and 80 mg were compared in a randomized double-blind study in 192 out-patients with stage II or III (Savary-Miller classification) reflux oesophagitis. Patients received either pantoprazole 40 mg (n = 97) or pantoprazole 80 mg (n = 95), once daily before breakfast for 4 weeks. Treatment was extended for a further 4 weeks if the oesophagitis had not healed.

RESULTS

After 4 weeks complete healing of the reflux oesophagitis was seen in 78% of protocol-correct patients given pantoprazole 40 mg daily (n = 86), and in 72% in the 80 mg (n = 87) group. The cumulative healing rates after 8 weeks were 95 and 94%, respectively (P > 0.05, Cochran-Mantel-Haenszel), and time until healing of oesophagitis comparable in both groups. Differences between doses were also not significant in an intention-to-treat analysis. Both dosing schedules were well tolerated and the patients experienced remarkable symptom relief. No adverse event or changes in laboratory values of clinical significance could definitely be ascribed to the trial medication.

CONCLUSION

The 40 mg pantoprazole dosage is comparable to 80 mg in reflux oesophagitis, both in efficacy and tolerability.

Expression of Ad4-BP/cytochrome P450 side chain cleavage enzyme and induction of cell death in long-term cultures of human granulosa cells

Freshly isolated granulosa cells obtained from women undergoing in-vitro fertilization (IVF) become refractory to further gonadotrophin stimulation in culture due to their previous hormonal treatment. However, when precultured for 7 days in gonadotrophin-free medium they regain their response to both human chorionic gonadotrophin (HCG) and follicle stimulating hormone (FSH) with a 10-fold and 5-fold increase in progesterone production respectively, within an additional 7 days of culture. Forskolin, a direct activator of adenylate cyclase, increased progesterone levels 12-fold compared with non-stimulated cultures. Oestradiol formation was also significantly elevated (P < 0.005) following 48 h stimulation with luteinizing hormone (LH), FSH or forskolin. Intracellular cAMP levels rose 1.5-fold, 10-fold and 15-fold after 1 h of FSH, HCG or forskolin treatment. Expression of both cytochrome P450 side chain cleavage enzyme (SCC) and the steroidogenic transcription factor SF1/Ad4BP could be demonstrated by Western blotting. However, elevation of P450 SCC alone was evident following FSH and HCG stimulation. In the presence of serum, the ultrastructure of these cultured cells displayed numerous lipid droplets and well-developed mitochondria, characteristic of highly steroidogenic cells. The proportion of apoptotic nuclei in these cultures was < 30%. Removal of the serum increased apoptotic incidence to 40%, whereas addition of FSH prevented cell death significantly (P < 0.01). HCG and forskolin increased apoptosis to approximately 50%, while treatment with 8Br-cAMP led to 80% cell death. Our data suggest that, after prolonged culture, human granulosa cells can regain cAMP and steroidogenic response to gonadotrophin stimulation. Moreover, our experiments indicate that apoptosis and steroidogenesis can coexist in the same cell population while the interrelationship between these processes can be determined by the intracellular levels of cAMP.

Perforation of the gastro-intestinal tract by a foreign body. A case report

Most ingested foreign bodies pass through the gastro-intestinal tract without giving rise to complications. If they become lodged in a narrow segment of the gastro-intestinal tract, perforation may occur. The resulting morbidity depends on the further route of the penetrating object and whether septic sequelae ensue. This article describes an unusual case of foreign body perforation with a protracted clinical course. It emphasises that there are no insurmountable barriers in the pathway of foreign bodies.

Iron, ascorbate and copper status of Sowetan Blacks with calcific chronic pancreatitis

Vitamin C can be used to overcome oxidative stress and ease pain in chronic pancreatitis. But its use is deprecated in conditions of tissue iron overload, because its bioactive form, ascorbate, can accelerate free-radical reactions that are driven by transition metals. We measured iron, ascorbate and copper in Sowetan Blacks (RSA) with chronic pancreatitis, obtaining serum/plasma from 14 consecutive patients and 15 controls. Compared with data from corresponding groups in Manchester, African samples had less ascorbate (p < 0.0001), but more caeruloplasmin (p < 0.0001). African and British controls had comparable iron and iron-binding capacity. Plasma from African patients had less ascorbate than that from African controls (p < 0.005) and in six samples, ferritin exceeded 300 micrograms/l (677 pmol/l). Low-molecular-mass iron or copper, capable of participating in free radical reactions, was not detected. British patients, had similar caeruloplasmin levels to African patients but higher ascorbate levels. There is no evidence of iron overload in our African samples. Outwardly healthy controls from Soweto have elevated levels of caeruloplasmin, possibly to compensate for dietary deficiency of ascorbate. Persistent oxidative stress is a unifying feature of chronic pancreatitis, but its degree is higher in African than British patients. Supplements of vitamin C should be safe in Blacks of southern Africa.