Measuring abscission spatiotemporal dynamics using quantitative high-resolution microscopy.

The spatiotemporal characteristics of ESCRT (Endosomal Sorting Complex Required for Transport)-mediated mammalian cytokinetic abscission have been studied in recent years using quantitative high-resolution light microscopy techniques. Here we describe how to apply spinning disk live cell imaging and structured illumination microscopy (SIM) to define the dynamics and structural organization of abscission and of proteins involved in abscission in a quantitative manner. We further provide a protocol to correlate the structural data, obtained by SIM, to the dynamic information obtained by live cell recordings.

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.

Lactase deficiency in the South African black population.

H2 breath analysis was carried out to determine the prevalence of lactase deficiency in different tribes of the South African Black population. Lactase deficiency was common (78%), despite the fact that two of the largest tribes (Zulu and Xhosa) are cattle herders and milk drinkers. This apparent anomaly is due to the consumption of a traditional fermented buttermilk, ("amasi" which has a low lactose content) instead of fresh milk. The most important reason for lactase deficiency, however, is that the South African Blacks originated in the West and Central African zone of nonmilking and took up dairying and milk use fairly recently. Thus they have not had enough time for genetic selection for lactase deficiency through life. The implications inherent in this study are that it would be more prudent to supply milk to developing countries in the form of a fermented milk product such as buttermilk. This is readily accepted by the Black population and would not be counter to accepted cultural practice.

PIP: H2 breath analysis was carried out to determine the prevalence of lactase deficiency in different tribes of the South African black population. Lactase deficiency was common (78%), despite the fact that 2 of the largest tribes (Zulu and Xhosa) are cattle herders and milk drinkers. This apparent anomaly is due to the consumption of a traditional fermented buttermilk (amasi) which has a low lactose content, instead of milk. The most important reason for lactase deficiency, however, is that the South African blacks originated in the West and Central African zone of nonmilking and took up dairying and milk use fairly recently. Thus they have not had enough time for genetic selection for lactase deficiency through life. Experience in Africa has shown that introducing skimmed milk causes diarrhea which may have catastrophic results in terms of mortality and morbidity. The implications inherent in this study are that it would be more prudent to supply milk to developing countries in the form of a fermented milk product such as buttermilk, prepared under traditional conditions and without refrigeration, since commercially prepared products do not have much less lactose and would also cause diarrhea in this population.

Reflux esophagitis therapy: sucralfate versus ranitidine in a double blind multicenter trial.

Sucralfate (Sc) suspension 6 g/day and ranitidine (Rn) tablets, 150 mg, were compared in 125 patients in a double-blind, multicenter, endoscopically controlled trial in the treatment of reflux esophagitis. Inclusion criteria were symptomatic reflux (number and severity of attacks) and endoscopic evidence of esophagitis (grades 1 to 4). Clinical assessments were performed on entry, and at 4 and at 8 weeks, and endoscopy was repeated at 8 weeks. Sc suspension and Rn placebo or Sc placebo and Rn tablets were taken on waking and immediately before retiring at night. Of the 125 patients, 27 were withdrawn because of default (Rn = 4; Sc = 14), noncompliance (Rn = 1; Sc = 2), or the development of congestive cardiac failure (Rn = 1), diarrhea (Rn = 1; Sc = 1), nausea (Sc = 1), constipation (Sc = 1), and hematemesis (Sc = 1). Analysis was performed on the remaining 98 patients, 43 of whom had been treated with Sc and 55 with Rn. Heartburn, acid regurgitation, epigastric pain, dysphagia, and chest pain were relieved in 34% vs 40%, 67% vs 72%, 71% vs 57%, and 86% vs 63% for Sc and Rn, respectively. There was no significant difference between the two groups. Endoscopic healing occurred in 47% of the Sc- and in 31% of the Rn-treated patients (chi 2 = 2.50), and healing or improvement was noted in 81% of the Sc- and 64% of the Rn-treated patients. This difference approached statistical significance (chi 2 = 3.73). There was no obvious endoscopic benefit in 8 of the 43 and 20 of the 55 patients in the groups treated with Sc and Rn, respectively. Although the findings with sucralfate and ranitidine in patients with reflux esophagitis completing the trial suggest a benefit of these agents, the absence of a placebo control group and the high default rates, particularly for those receiving sucralfate, preclude any firm conclusions as to relative or specific efficacy of these agents in this condition.

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.

Analysis of anesthetic action on the potassium channels of the Shaker mutant of Drosophila.

Recent evidence suggest that exposure to volatile anesthetic agents causes a change in conductance through an undelineated potassium channel. With recently developed genetic and molecular techniques the Drosophila melanogaster (D.m.) genome can be manipulated to study the role that potassium ion channel function plays in anesthetic action. The IA potassium channel is encoded by the Shaker (Sh) locus on the X chromosome of D.m. Because this channel may be one of those involved in volatile anesthetic action, we tested the sensitivity to isoflurane in three Shaker strains with different degrees of dysfunctional IA conductance (Shnull greater than ShKS133 greater than Sh5). Anesthetic sensitivity was also examined in mutant strains of D.m. which express abnormalities either in other potassium channel conductances (eag, slo) or other ion conductances (para). The normally conducting wild type served as the control. Two-day-old adult D.m. were stimulated with a heat source during exposure to the volatile anesthetic isoflurane, and the number moving in response to the noxious stimulus was noted. After testing the Shaker and control strains at no fewer than 13 concentrations, the IC50S (isoflurane concentration in percent vol/vol at which 50% of the flies did not respond to the heat stimulus) were derived. The IC50 values for Sh 5 (0.89), Sh133 (1.29), and Shnull (1.37) were significantly different from the wild type (0.56). The rank order of insensitivity of these Shaker mutants corresponded to the extent of the alteration in IA conductance as established by previous studies in these mutants. Neither eag (0.66), para (0.48), nor slo (0.63) differed significantly from the wild type. These data suggest that the IA potassium channel plays a role in volatile anesthetic action.

Pancreatic ascites and effusion. Risk factors for failure of conservative therapy and the role of octreotide.

The possible risk factors for failure of medical therapy were examined in 23 patients with pancreatic ascites or effusion. The ascites or effusion resolved completely in 10 patients after a mean (+/- SEM) of 30 +/- 2 days of conventional medical treatment. In five patients in whom conventional medical therapy failed, the addition of an octreotide (SMS 201-995) analogue to the medical therapy led to a resolution of the ascites (three patients) or effusion (two patients). Six patients underwent surgery after failed medical therapy, one patient died while receiving conservative therapy, and one patient refused hospital treatment. Serum sodium and albumin levels were significantly lower, and the ratio of total fluid protein to total serum protein was significantly higher in the group that failed to heal in response to conventional medical therapy. Nine of 11 patients with mild to moderately severe chronic pancreatitis healed in response to conservative therapy. Only one of 10 patients with advanced pancreatitis healed in response to conventional medical therapy. Our results suggest that a selective surgical approach is warranted to treat pancreatic ascites and effusion. In patients with mild or moderately severe pancreatitis, medical therapy is recommended. Patients with advanced pancreatic disease should be selected for early surgery. Octreotide may be useful in the patient in whom surgery may be associated with a prohibitive morbidity or mortality.

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.

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.

Modulating role of dopamine on anesthetic requirements.

The influence of dopamine on halothane anesthetic requirements was determined in mice. Halothane anesthetic requirement was defined as the minimum anesthetic concentration (MAC) that prevented 50% animals from moving in response to a supramaximal stimulus. Levodopa (L-DOPA) dose-dependently decreased halothane MAC to a maximum of 49% of control; over the same dose range L-DOPA increased striatal dopamine nearly 4-fold. The MAC-reducing effect of L-DOPA was attenuated by selective antagonism of the D2 dopamine receptor with YM-09151-2 while selective blockade of the D1 dopamine receptor with SCH-23390 did not alter L-DOPA's effect on the MAC for halothane. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) decreased striatal dopamine by 82% and increased the MAC for halothane by 27%. Repletion of striatal dopamine with L-DOPA, in MPTP-treated mice, restored the MAC for halothane back to the control state. The regression line derived from the plot of halothane MAC versus striatal dopamine content shows a highly significant correlation between the two variables (r2 = 0.94). These are the first results to suggest that anesthetic requirements can be modulated directly and precisely by increasing or decreasing the content of a single neurotransmitter in the central nervous system.

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.

Can premature luteinization in superovulation protocols be prevented by aspiration of an ill-timed leading follicle?

In 12 patients stimulated for in vitro fertilization and embryo transfer (IVF-ET), a single leading follicle developed, whereas the other follicles were 6 mm smaller. In 7 patients chosen at random (group A), the leading follicle was aspirated, whereas in the other 5 the leading follicle was allowed to continue growing (group B). Comparison of the hormonal pattern of both groups showed that a premature luteinizing hormone (LH) surge was avoided only in group A, and only in this group a second follicle aspiration for IVF-ET was done, and two pregnancies were achieved. In group B, aspiration for IVF-ET was canceled because of premature LH surge. It is suggested that aspiration of a single leading follicle during ovulation induction may be an efficient method to avoid premature LH surge enabling other follicles to develop up to the preovulatory stage.

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.

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.

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.

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.

Cancer patterns in three African populations compared with the United States black population.

Cancer incidence rates and patterns in three African populations in the Gambia, Mali and South Africa, have been compared with corresponding data on the Black population in Connecticut, USA. In the African populations, total rates for cancer are much lower than that of US Blacks, even allowing for under-reporting. Chief cancers are those of the oesophagus, liver and cervix. In Mali, stomach cancer is very common. As to trends, among South African Blacks, a population in transition, rates are rising, albeit slowly, of cancers of prosperity--prostate, lung, breast and colon-rectum. Salient questions are: can the number of cancers of underprivilege be lessened, and can cancers linked with rising socioeconomic states be restrained? Discussions of common risk factors, including diet, reproduction, smoking and drinking practices, indicate that for Africans as a whole, continuing poverty will prevent major changes in cancer pattern and rises in occurrence of the disease. However, should prosperity increase for Africans in big cities, rates are ultimately likely to attain those prevailing in the US Black population. Significant avoiding action seems almost impossible.

Micronutrient antioxidant status in black South Africans with chronic pancreatitis: opportunity for prophylaxis.

Biochemical assessments of micronutrient antioxidant status were done in 14 consecutive black patients with calcific chronic pancreatitis and 15 controls at Soweto, near Johannesburg in southern Africa. The patients showed subnormal levels of vitamin C in plasma; selenium, beta-carotene and alpha-tocopherol in serum; and inorganic sulphate (as an index of long-term sulphur amino acid intake) in urine (P < 0.001 for each): furthermore, among the patients ascorbate constituted a lower fraction of vitamin C (P < 0.002), indicating heightened oxidation of the bioactive form. By comparing the results in Sowetan controls with reference ranges from Manchester, UK, the markedly lower vitamin C and, hence, ascorbate levels in the Sowetans was underlined (P < 0.001) and their selenium levels were also lower (P < 0.001), but beta-carotene, alpha-tocopherol and inorganic sulphate levels were comparable. The very low bioavailability of ascorbate among Sowetan controls is reminiscent of our previous finding in outwardly healthy people at Madras in southern India: in both these areas chronic pancreatitis is currently endemic, has a propensity to pancreatic calculi and runs a virulent course towards premature death from diabetes, malnutrition or pancreatic cancer. Considering that low ascorbate levels are a feature in patients with chronic pancreatitis who develop pancreatic calculi at Manchester and that antioxidant supplements ameliorate painful symptoms, we suggest that poor antioxidant intake may predispose underprivileged tropical communities to the disease. If so, there could be an opportunity for prophylaxis through a daily tablet containing vitamin C, perhaps along with selenium at Soweto and beta-carotene at Madras.

Heightened free radical activity in blacks with chronic pancreatitis at Johannesburg, South Africa.

Four indices of free radical activity were measured in fasting serum/plasma samples from 14 consecutive blacks with clinically quiescent chronic pancreatitis and 15 outwardly healthy hospital personnel at Soweto, the township near Johannesburg in South Africa. The patients had higher serum levels than did controls of lipid isomerisation (P < 0.002) and peroxidation (P < 0.05) markers, with lower plasma levels of glutathione (P < 0.0001) and bioactive fraction of vitamin C (P < 0.002). Lipid peroxide and non-bioavailable vitamin C concentrations in Sowetan patients were significantly higher than in their counterparts from Manchester, UK (P < 0.0001, P < 0.0005, respectively). These differences mirrored those in controls in that outwardly healthy Sowetans had much higher serum lipid peroxide levels than Manchester controls (P < 0.001) and much lower plasma concentration of vitamin C (P < 0.001) and hence of the bioavailable fraction ascorbate (P < 0.0002). Heightened free radical activity is thus a common denominator in chronic pancreatitis irrespective of geography, or putative aetiological factors whether alcoholism or idiopathic, since that ratio was approximately 95:5 at Johannesburg and 50:50 at Manchester. The further finding of subclinical oxidative stress in Sowetan controls and the endemic nature of chronic pancreatitis in that area supports the hypothesis that oxidative stress may be involved in its pathogenesis.

A preliminary report on urinary BT-PABA/PAS excretion index, serum pancreatic isoamylase and faecal chymotrypsin tests of pancreatic dysfunction in Sowetan Africans.

The steady increase in chronic pancreatitis among black Africans at Soweto, RSA, in the past 40 years necessitates an objective and non-invasive test to detect the disease at an early stage. Given the biphasic nature of the disease--secretory hyperfunction with periodic active inflammatory episodes followed by steady exocrine impairment--we assessed three potential aids. Urinary BT-PABA/PAS excretion index (PEI), serum pancreatic isoamylase (PIA) and faecal chymotrypsin activity (FCA) were measured in the following groups: 16 outwardly healthy hospital workers, 16 consecutive patients with calcifying chronic pancreatitis and 19 with abdominal pain ascribed to other conditions (disease controls). (1) Healthy controls had lower PEI than those at Manchester, UK, or Madras, India, from subclinical acinar loss--as shown by lower PABA recovery whereas intestinal absorptive capacity was maintained, as shown by recovery of PAS. (2) Using the popular cut-off for PEI (0.75) only 9 of 14 patients with chronic pancreatitis were identified (sensitivity 64%, 2 tests unsatisfactory), while a value of less than 0.54, the mean -2 S.D. in local controls, yielded sensitivity of 50%. (3) If PEI of less than 0.75 or PIA outside the reference range was taken to indicate the disease, 5 of 9 disease controls would have been classed as chronic pancreatitis (among those with both tests satisfactory): retrospective ultrasound scans did not identify these. (4) Although FCA was less than the preselected cut-off, 5 units/g, in every patient with chronic pancreatitis (100% sensitivity) its poor predictive value was indicated by low specificity: subnormal levels in 4 of 14 and 6 of 16 healthy controls or disease controls, respectively, most of whom had near-normal values of PEI, PIA or both. (5) Collectively, these results suggest a high frequency of subclinical chronic pancreatitis at Soweto, but also that the combination of tests required to identify it may prove impractical--whether in field surveys or hospital practice.