Transgenic tomato plants with decreased sucrose synthase are unaltered in starch and sugar accumulation in the fruit

Sucrose is the photoassimilate transported from the leaves to the fruit of tomato yet the fruit accumulates predominantly glucose and fructose. Hydrolysis of sucrose entering the fruit can be accomplished by invertase or sucrose synthase. Early in tomato fruit development there is a transient increase in sucrose synthase activity and starch which is correlated with fruit growth and sink strength suggesting a regulatory role for sucrose synthase in sugar import. Using an antisense sucrose synthase cDNA under the control of a fruit-specific promoter we show that sucrose synthase activity can be reduced by up to 99% in young fruit without affecting starch or sugar accumulation. This result calls into question the importance of sucrose synthase in regulating sink strength in tomato fruit.

Small-diameter PTFE portosystemic shunts: portocaval vs mesocaval

Fifty-seven patients with failed sclerotherapy received a mesocaval interposition shunt with an externally supported, ringed polytetrafluoroethylene prosthesis of either 10 or 12 mm diameter. Thirty-one patients had Child-Pugh grade A disease and 26 grade B; all had a liver volume of 1000-2500 ml. Follow-up ranged from 16 months to 6 years 3 months. Three patients (5 per cent) died in the postoperative period. There were two postoperative recurrences of variceal haemorrhage and one recurrent bleed in the second year after surgery. The cumulative shunt patency rate was 95 per cent and the incidence of encephalopathy 9 per cent; the latter was successfully managed by protein restriction and/or lactulose therapy. The actuarial survival rate for the whole group at 6 years was 78 per cent, for those with Child-Pugh grade A 88 per cent and for grade B 67 per cent. Small-lumen mesocaval interposition shunting achieves portal decompression, preserves hepatopetal flow, has a low incidence of shunt thrombosis, prevents recurrent variceal bleeding and is not associated with significant postoperative encephalopathy.

A Voluntary Smokers' Registry: Characteristics of joiners and non-joiners in the Community Intervention Trial for Smoking Cessation (COMMIT)

OBJECTIVES

This paper examines differences between joiners and nonjoiners of a voluntary smokers' registry.

METHODS

A baseline prevalence survey was used to identify characteristics of smokers who joined or did not join a smokers' registry.

RESULTS

Communities varied significantly in registry enrollment rates. Heavy-smoking joiners expressed more desire to quit, were more likely to live with nonsmokers, and were older than nonjoiners. Light-to-moderate joiners smoked more, were more addicted to cigarettes, and expressed more desire to quit than nonjoiners.

CONCLUSIONS

Few baseline characteristics differentiated joiners from nonjoiners. Nonjoiners were significantly more likely to achieve cessation than joiners.

A multicentre randomised trial comparing octreotide and injection sclerotherapy in the management and outcome of acute variceal haemorrhage

BACKGROUND

Few studies have compared vasoactive drugs with endoscopic sclerotherapy in the control of acute variceal haemorrhage. Octreotide is widely used for this purpose, but its value remains undetermined.

AIMS

To compare octreotide with endoscopic sclerotherapy for acute variceal haemorrhage.

PATIENTS

Consecutive patients with acute variceal haemorrhage.

METHODS

Patients were randomised at endoscopy to receive either a 48 hour intravenous infusion of 50 pg/h octreotide (n = 73), or emergency sclerotherapy (n = 77).

RESULTS

Overall control of bleeding and mortality was not significantly different between octreotide (85%, 62 patients) and sclerotherapy (82%, 63 patients) over the 48 hour trial period (relative risk of rebleeding 0.83; 95% confidence interval (CI) 0.38 to 1.82), irrespective of Child's grading or active bleeding at endoscopy. One major complication was observed in the sclerotherapy group (aspiration) and two in the octreotide group (pulmonary oedema, severe paralytic ileus). During 60 days of follow up there was an overall trend towards an increased mortality in the octreotide group which was not statistically significant (relative risk of dying at 60 days 1.91, 95% CI 0.97 to 3.78, p = 0.06).

CONCLUSIONS

The results of this study indicate that intravenous octreotide is as effective as injection sclerotherapy in the control of acute variceal bleeding, but further controlled trials are necessary to evaluate the safety of this treatment.

Murine CTLA4-IgG treatment inhibits airway eosinophilia and hyperresponsiveness and attenuates IgE upregulation in a murine model of allergic asthma

Antigen-specific T-cell activation requires the engagement of the T-cell receptor (TCR) with antigen as well as the engagement of appropriate costimulatory molecules. One of the most important pathways of costimulation is the interaction of CD28 on the T cell with B7-1/B7-2 on antigen-presenting cells. In the present study, we have examined the in vivo effects of blocking the CD28:B7 T-cell costimulatory pathway by administration of mCTLA4-IgG in a murine model of allergic asthma. Mice were sensitized with ovalbumin and exposed to repeated ovalbumin inhalation challenges. In mice treated with a control antibody at the time of ovalbumin challenge a significant increase in the number of eosinophils (12.8 +/- 4.3 x 10(3) cells, P < 0.05) in the bronchoalveolar lavage (BAL) fluid and airway hyperresponsiveness to methacholine (49 +/- 15%, P < 0.05) was observed. In addition, serum levels of ovalbumin-specific IgE were significantly (P < 0.01) increased after ovalbumin challenge compared with saline challenge (1,133 +/- 261 experimental units [EU]/ml and 220 +/- 63 EU/ml, respectively). In mice treated with mCTLA4-IgG at the time of ovalbumin challenge, the infiltration of eosinophils into BAL fluid and the development of airway hyperresponsiveness to methacholine were completely inhibited. The upregulation of ovalbumin-specific IgE levels in serum was attenuated by mCTLA4-IgG treatment. Furthermore, addition of mCTLA4-IgG to cultures of parabronchial lymph node cells from sensitized mice inhibited the ovalbumin-induced interleukin-4 production. These data indicate the therapeutic potential of blocking T-lymphocyte costimulation by CTLA4-IgG as a possible immunosuppressive treatment for patients with allergic asthma.

Improving diabetes care in the primary health setting. The Indian Health Service experience

PURPOSE

To identify key systems issues from the Indian Health Service (IHS) experience that must be addressed to improve metabolic control among patients with non-insulin-dependent diabetes mellitus (NIDDM) who were followed in primary care settings.

DATA SOURCES

Records of diabetic patients seen in IHS facilities in specific geographic regions from 1987 to 1994.

STUDY SELECTION

A representative sample of charts from each facility was reviewed yearly to measure key variables. The sampling frame was the number of diabetic patients currently active on the registry and the sample size calculated to measure a 10% change in selected practices at each facility.

EXTRACTION

Regional diabetes coordinators reviewed charts or trained local providers to sample and extract data in a standard format.

RESULTS

Regional data were examined to show trends in the performance of immunizations and foot examinations and in other variables such as hypertension and metabolic control. The percentage of diabetic patients who received a single dose of pneumococcal vaccine improved from 24% in 1987 to 1988 to 57% in 1994 (P < 0.01 for trend) among diabetic patients in Minnesota, Wisconsin, and Michigan. Rates of yearly comprehensive foot examination increased from 36% to 58% (P < 0.01 for trend) over the same period. In Montana and Wyoming, the percentage of diabetic patients with uncontrolled hypertension (defined as the mean of three systolic blood pressure measurements of > or = 140 mm Hg or diastolic pressure measurements > or = 90 mm Hg, or both, during the previous year) decreased from 36% in 1992 to 25% in 1993 after the regional diabetes coordinator emphasized hypertension control. In 1994, when less emphasis was placed on hypertension, 33% of the diabetic patients had uncontrolled hypertension. Estimates of metabolic control from records of diabetic patients in Washington, Oregon, and Idaho in 1994 showed that 29% of patients had excellent metabolic control (a hemoglobin A1c [HbA1c] level < or = 7.5% or mean blood glucose level < or = 9.2 mmol/L) within the past year; only 9% experienced poor control (a HbA1c level > 12% or mean blood glucose level > 18.9 mmol/L).

CONCLUSIONS

The IHS experience shows that standard, ongoing monitoring of key variables allows facilities to improve diabetes care. Simple, reliable methods of defining metabolic control combined with a feedback system in the primary care setting are needed to improve metabolic control in patients with NIDDM.

Octreotide in the control of post-sclerotherapy bleeding from oesophageal varices, ulcers and oesophagitis

Bleeding from oesophageal varices, oesophageal ulcers or oesophagitis is occasionally massive and difficult to control. Octreotide, a synthetic analogue of somatostin lowers portal pressure and collateral blood flow including that through varices, increases lower oesophageal sphincter pressure, and inhibits the gastric secretion of acid as well as pepsin. Our current experience suggests it is effective in controlling acute variceal haemorrhage. Therefore we have examined the efficacy of octreotide in the control of post-sclerotherapy bleeding from oesophageal varices, oesophageal ulcers and oesophagitis. During the study period 77 patients experienced a significant gastrointestinal bleed (blood pressure < 100 mm Hg, pulse > 100 beats per min or the need to transfuse 2 or more units of blood to restore the hemoglobin level) following injection sclerotherapy of oesophageal varices. The source of bleeding was varices in 42 patients, oesophageal ulcers in 31 and oesophagitis in 4. All patients received a continuous intravenous infusion of octreotide (50 micrograms/h) for between 40-140h. If bleeding was not controlled in the first 12h after commencing octreotide hourly bolus doses (50 micrograms) for 24h were superimposed on the continuous infusion. Haemorrhage was successfully controlled by an infusion of octreotide in 38 of the 42 patients with bleeding from varices, in 30 of 31 patients with oesophageal ulceration, and all patients with oesophagitis. In the 1 patient with persistent bleeding from oesophageal ulceration and in 2 of the 4 with continued haemorrhage from varices, haemostasis was achieved by hourly boluses of 50 micrograms octreotide for 24h in addition to the continuous infusion. No major complications were associated with octreotide administration. The results of this study clearly indicate that octreotide is a safe and effective treatment for the control of severe haemorrhage after technically successful injection of sclerotherapy.

Alcohol and oesophageal varices

Oesophageal varices are abnormally dilated veins that develop beneath the mucosa of the lower oesophagus and upper stomach and cause profound gastrointestinal haemorrhage associated with a high mortality. Varices develop in the presence of protal hypertension, which, in Europe and the USA, is most commonly due to alcoholic cirrhosis of the liver. Alcoholic cirrhosis develops in 10-20% of chronic ethanol abusers as a result of prolonged hepatocyte damage, leading to centrilobular inflammation and fibrosis. The net effect on the portal venous system is an elevation of resistance, and/or increase of inflow, producing portal hypertension, and the development of collateral channels in the form of varices. Such parenchymal liver disease also causes ascites, clotting deficiencies, secondary malnutrition and hepatic encephalopathy, all of which contribute to the high mortality associated with variceal haemorrhage. Variceal bleeding is more likely to occur when the varices are large, long and numerous, with surface red markings, and may be precipitated to respiratory tract infection, non-steroidal anti-inflammatory drugs, alcohol, or may occur spontaneously. Once identified by endoscopy, the aims of management are to control the haemorrhage, to prevent recurrent haemorrhage, and to treat the underlying cause of portal hypertension. Attention to nutrition and long-term rehabilitation are particularly important in those alcoholic cirrhotic patients who survive.

The binding site on human immunoglobulin E for its high affinity receptor

Immunoglobulin (Ig) E antibodies mediate allergic responses by binding to specific high affinity receptors, Fc epsilon RI, on mast cells and basophils. Previous studies have shown that the principal Fc epsilon RI binding site is located on the third constant domain, Fc epsilon 3, of IgE. Based on a model of the IgE Fc epsilon 3 (which is homologous to the second constant domain of IgG), homology scanning mutagenesis and replacement of individual residues were used to determine the specific amino acids of human IgE involved in binding to human Fc epsilon RI. The amino acids are localized in three loops, which form a putative ridge on the most exposed side of the Fc epsilon 3 domain of IgE and include Arg-408, Ser-411, Lys-415, Glu-452, Arg-465, and Met-469. The preponderance of charged residues suggests that IgE-Fc epsilon RI binding is mediated primarily by electrostatic interaction. Furthermore, it is possible to confer Fc epsilon RI binding to an IgG molecule by introducing these three IgE loops into the IgG C gamma 2 domain.

A trans-spliced leader RNA sequence in plant parasitic nematodes

A trans-spliced leader gene has been identified in the genomes of the potato cyst nematodes Globodera rostochiensis and G. pallida. The gene contains a 22-nt sequence identical to that of the leader sequence of Caenorhabditis elegans, a consensus splice donor site and a putative Sm antigen binding site. In common with other nematodes the spliced leader gene is present in tandem repeating units together with the 5S ribosomal RNA gene. Variation in the length of the intergenic spacer region has permitted the design of polymerase chain reaction primers which can be used to reveal repeat length variants diagnostic for G. rostochiensis and G. pallida and the Pa1 pathotype of G. pallida.

Administration of an anti-IgE antibody inhibits CD23 expression and IgE production in vivo

High IgE responder BDF1 mice were immunized intraperitoneally (i.p.) with dinitrophenol4 (DNP4)-ovalbumin (OVA) in alum concomitant with intravenous (i.v.) administration of an anti-IgE monoclonal antibody (mAb). IgE levels were undetectable in mice treated with the anti-IgE antibody, whereas mice treated with isotype-matched irrelevant mAb had IgE levels comparable to that of untreated, immunized mice. Subsequent antigen challenges with DNP4-OVA, either at weekly or monthly intervals, failed to evoke an IgE response for greater than 2 months in mice treated with anti-IgE during the primary sensitization, even though the terminal half-life of the anti-IgE antibody was 7 days. This inhibition was specific for DNP4-OVA since the DNP4-OVA-suppressed mice were able to respond to keyhole limpet haemocyanin (KLH). To investigate the effects of antibody treatment at the cellular level, passive transfer experiments were performed. The primary DNP-specific IgE response of adoptive transfer recipient mice was the same whether the donor cells were from mice treated with IgG or anti-IgE. Transfer of enriched T- or B-cell populations indicated that T-cell help was not compromised by administration of the anti-IgE mAb. However, splenocytes from the anti-IgE-treated mice failed to synthesize IgE in vitro, and flow cytometric analysis of B cells from anti-IgE-treated mice showed a dose-dependent decrease in CD23+ cells following antibody treatment, which correlated with decreased serum IgE levels. Taken together, the results of these studies suggest that anti-IgE treatment suppresses IgE responses via effects on B cells rather than T cells, possibly through effects on CD23-dependent pathways.

Crohn's disease and myasthenia gravis: a possible role for thymectomy

A female patient with a three year history of Crohn's disease of the colon developed myasthenia gravis. Despite diversion of the faecal stream by an ileostomy, and total colectomy, the patient had continuing problems with perineal and perianal abscesses and fistulas. Her myasthenia gravis became unresponsive to anti-cholinergics so a thymectomy was performed. The perineal and perianal disease improved subsequently. This case supports the theory that functional disturbances of the thymus may have a role in the pathogenesis of inflammatory bowel disease.

Human IgE receptor alpha-chain IgG chimera blocks passive cutaneous anaphylaxis reaction in vivo

Cross-linking of the high affinity IgE receptor (Fc epsilon RI) expressed on mast cells and basophils is essential for triggering anaphylaxis in vivo. Previously, other investigators have tried to produce competitive inhibitors using IgE peptide analogues and anti-IgE antibodies with limited success. To create a novel specific inhibitor of IgE that can block binding of IgE to Fc epsilon RI without the capacity to stimulate degranulation, we made an Fc epsilon RI-IgG immunoadhesin. The Fc epsilon RI-IgG was constructed by gene fusion of the extracellular portion of the human alpha-chain of Fc epsilon RI, which contains the high affinity binding site for IgE, with a truncated human IgG1 H chain C region. The Fc epsilon RI-IgG recognizes both human and murine IgE. Coincubation of Fc epsilon RI-IgG with murine IgE prevented sensitization of RBL-2H3 cells and the subsequent histamine release in response to anti-IgE. Similarly, when the Fc epsilon RI-IgG was preincubated with equimolar concentrations of either hyperimmune mouse sera or purified mouse IgE, it completely blocked the passive cutaneous anaphylaxis reaction in rats. Furthermore, i.v. administration of Fc epsilon RI-IgG following intracutaneous injection of serum from DNP-immunized mice was able to block the passive cutaneous anaphylaxis reaction in a time-dependent fashion. These results demonstrate that Fc epsilon RI-IgG is a potent inhibitor of IgE binding to intracutaneous mast cells in vivo and may prove clinically useful for the treatment of IgE-mediated disease.

Human IgE receptor alpha-chain IgG chimera blocks passive cutaneous anaphylaxis reaction in vivo

Cross-linking of the high affinity IgE receptor (Fc epsilon RI) expressed on mast cells and basophils is essential for triggering anaphylaxis in vivo. Previously, other investigators have tried to produce competitive inhibitors using IgE peptide analogues and anti-IgE antibodies with limited success. To create a novel specific inhibitor of IgE that can block binding of IgE to Fc epsilon RI without the capacity to stimulate degranulation, we made an Fc epsilon RI-IgG immunoadhesin. The Fc epsilon RI-IgG was constructed by gene fusion of the extracellular portion of the human alpha-chain of Fc epsilon RI, which contains the high affinity binding site for IgE, with a truncated human IgG1 H chain C region. The Fc epsilon RI-IgG recognizes both human and murine IgE. Coincubation of Fc epsilon RI-IgG with murine IgE prevented sensitization of RBL-2H3 cells and the subsequent histamine release in response to anti-IgE. Similarly, when the Fc epsilon RI-IgG was preincubated with equimolar concentrations of either hyperimmune mouse sera or purified mouse IgE, it completely blocked the passive cutaneous anaphylaxis reaction in rats. Furthermore, i.v. administration of Fc epsilon RI-IgG following intracutaneous injection of serum from DNP-immunized mice was able to block the passive cutaneous anaphylaxis reaction in a time-dependent fashion. These results demonstrate that Fc epsilon RI-IgG is a potent inhibitor of IgE binding to intracutaneous mast cells in vivo and may prove clinically useful for the treatment of IgE-mediated disease.

An in vivo 31P MRS study of patients with liver cirrhosis: progress towards a non-invasive assessment of disease severity

Fourteen patients with liver cirrhosis of differing severity participated in a one-dimensional chemical shift imaging 31P MRS study of the liver. Patients were divided into two groups according to the severity of their liver disease using Child's classification and the aminopyrine breath test (AB test). Seven normal volunteers without liver disease acted as controls. The phosphomonester (PME) peak in normal subjects was 4.77% (95% confidence interval, CI: 4.11-5.42) of total phosphorus. The PME peak was significantly elevated in both mild cirrhosis [5.80% (95% CI: 5.46-6.14), p = 0.0051, vs normal subjects] and severe cirrhosis [9.64% (95% CI: 8.71-10.57), p = 0.0002, vs normal subjects and p = 0.001, vs mild cirrhosis]. There was a significant negative linear correlation (r = 0.88, p < 0.01) of PME with the percentage dose of 14CO2 excreted over 2 h in the AB test. pH values in patients with mild cirrhosis [7.45 (95% CI: 7.35-7.55)] but not severe cirrhosis [7.36 (95% CI: 7.25-7.47)] were significantly elevated (p = 0.04) compared to normal subjects [7.29 (95% CI: 7.17-7.41)]. Comparison of the peak area of PME at TR = 0.5 s against that using TR = 5.0 s in cirrhotic liver suggested no reduction in T1 of phosphorus metabolites in cirrhosis. A relationship between the severity of liver cirrhosis and a relative increase in PME was demonstrated and this was not due to a reduction of T1. This study highlights the clinical potential of 31P MRS as a non-invasive means of assessing the severity of liver cirrhosis.