The relationship between insulin, IGF-I and weight gain in cystic fibrosis

OBJECTIVE

In cystic fibrosis, reduced body mass is related to low levels of IGF-I and changes in the IGF binding proteins. Our aim was to determine whether these abnormalities are linked to pancreatic endocrine dysfunction.

PATIENTS AND DESIGN

We measured serum levels of insulin, IGF-I, IGFBP-I, IGFBP-3 and IGF bioactivity in 77 fasting subjects (43 male) mean age 9.6 years (range 2.99-17.98 years). Data were analysed with respect of body mass, puberty and stature and compared with control data established in the same laboratory.

RESULTS

The mean height standard deviation score (SDS (SD)) was -0.54 (0.97) and the body mass index SDS -0.24 (1.09). Both body mass index SDS (r = -0.40, P = 0.0003) and IGF-I SDS (r = - 0.32, P = 0.009) declined with age. Insulin levels were also low and correlated with IGF-I and IGFBP-3 (r = 0.42, P = 0.0004, and r = 0.45, P = 0.0002, respectively) whereas levels of IGFBP-I were inversely related to those of IGF-I and insulin (r = - 0.43, P = 0. 0004, r = - 0.52, P < 0.0001). IGF bioactivity was reduced and inversely related to IGFBP-I (r = - 0.31, P = 0.009). In multiple regression analysis, body mass index SDS was negatively related to age (P < 0.0001) and positively related to insulin and IGF-I (P = 0. 04, P = 0.03, respectively). Height SDS was correlated with IGF bioactivity (P = 0.003) and negatively with IGFBP-I (P = 0.01).

CONCLUSIONS

We conclude that progressive insulin deficiency may result in reduced IGF-I levels and IGF-bioactivity and may determine weight gain and statural growth in cystic fibrosis.

Serum total homocysteine and coronary heart disease: prospective study in middle aged men

OBJECTIVES

To examine the prospective relation between total homocysteine and major coronary heart disease events.

DESIGN

A nested case-control study carried out within the British regional heart study, a prospective investigation of cardiovascular disease in men aged 40-59 years at entry. Serum total homocysteine concentrations were analysed retrospectively and blindly in baseline samples from 386 cases who had a myocardial infarct during 12.8 years of follow up and from 454 controls, frequency matched by age and town.

RESULTS

Geometric mean serum total homocysteine was slightly higher in cases (14.2 micromol/l) than in controls (13.5 micromol/l), a proportional difference of 5.5% (95% confidence interval (CI) -0.02% to 10.8%, p = 0.06). Age adjusted risk of myocardial infarction increased weakly with log total homocysteine concentration; a 1 SD increase in log total homocysteine (equivalent to a 47% increase in total homo cysteine) was associated with an increase in odds of myocardial infarction of 1.15 (95% CI 1.00 to 1. 32; p = 0.05). The relation was particularly marked in the top fifth of the total homocysteine distribution (values >16.5 micromol/l), which had an odds ratio of 1.77 (95% CI 1.28 to 2.42) compared with lower levels. Adjustment for other risk factors had little effect on these findings. Total homocysteine concentrations more than 16.5 micromol/l accounted for 13% of the attributable risk of myocardial infarction in this study population. Serum total homocysteine among control subjects varied between towns and was correlated with town standardised mortality ratios for coronary heart disease (r = 0.43, p = 0.08).

CONCLUSIONS

Serum total homocysteine is prospectively related to increased coronary risk and may also be related to geographical variation in coronary risk within Britain. These results strengthen the case for trials of total homocysteine reduction with folate.

Gene therapy in transplantation

Facilitation of solid organ and cell transplantation depends on metabolic and immunologic factors that can be manipulated ex vivo and in vivo using gene transfer technology. Vectors have been developed which can optimally transfer relevant genes to various tissues and organs. Interventions aimed at promoting tissue preservation before transplantation, prevention of oxidative stress and immunological rejection have recently become attractive options using viral and nonviral gene delivery vehicles. Further understanding of the mechanisms involved in tolerance induction as well as the facilitation of xenogeneic engraftment have made possible a variety of avenues that can be exploited using gene transfer technology.

New thrombolytic drugs

Thrombolytic drugs reduce mortality from myocardial infarction and research is focused on newer drugs with improved clinical efficacy. The ideal thrombolytic drug should be effective in dissolving fresh and older thrombi, be rapid in its action with complete dissolution of the thrombus, be able to be given as a bolus and be safe without hypotensive or allergic or immunogenic reactions. The types of agents being developed fall into five broad categories: * mutants or variants of single chain urokinase type plasminogen activator; * mutants or variants of tissue type plasminogen activator; * recombinant chimaeric plasminogen activators; * conjugates of plasminogen activators and anti-fibrin monoclonal antibodies; * compounds derived from haemophagous animals. Within the mutant and variant groups there may be single point mutations which increase the half life or deletion of various amino acid sequences to increase resistance to plasma protease inhibitors or cause more selective binding to fibrin. The recombinant chimaeric plasminogen activators are designer drugs where the kringle regions, the growth hormone domain region, the finger domain region and the serine protease part of the molecules are all cleaved and recombined in various ways to improve potency. The conjugates of plasminogen activators and anti-fibrin and monoclonal antibodies improve the targeting of the agent to fibrin clot. Monoclonal antibodies are commonly used against the seven aminoterminal residues of the beta chain of fibrin. These are cross linked and bound to plasminogen activators. A variety of substances from haemophageous animals are currently being studied including salivary plasminogen activator from vampire bats, venom from southern copperhead snakes and staphylokinase from bacteria. Currently available thrombolytic agents have many limitations, but the novel thrombolytic agents have yet to be tested in clinical trials. With few exceptions, they all act via the plasminogen system and it may be in the future that combinations of anti-platelet and thrombolytic agents may prove to be more efficacious than thrombolytics and aspirin alone.

Chimerism and xenotransplantation. New concepts

In both transplant and infectious circumstances, the immune response is governed by migration and localization of the antigen. If the antigenic epitopes of transgenic xenografts are sufficiently altered to avoid evoking the destructive force of innate immunity, the mechanisms of engraftment should be the same as those that permit the chimerism-dependent immunologic confrontation and resolution that is the basis of allograft acceptance. In addition to "humanizing" the epitopes, one of the unanswered questions is whether the species restriction of complement described in 1994 by Valdivia and colleagues also necessitates the introduction of human complement regulatory genes in animal donors. Because the liver is the principal or sole source of most complement components, the complement quickly is transformed to that of the donor after hepatic transplantation. Thus, the need for complementary regulatory transgenes may vary according to the kind of xenograft used. Much evidence shows that physiologically important peptides produced by xenografts (e.g., insulin, clotting factors, and enzymes) are incorporated into the metabolic machinery of the recipient body. To the extent that this is not true, xenotransplantation could result in the production of diseases that are analogous to inborn errors of metabolism. In the climate of pessimism that followed the failures of baboon to human liver xenotransplantation in 1992-1993, it seemed inconceivable that the use of even more discordant donors, such as the pig, could ever be seriously entertained; however, this preceded insight into the xenogeneic and allogeneic barriers that has brought transplantation infectious immunity to common ground. With this new insight and the increasing ease of producing transgenic donors, the goal of clinical xenotransplantation may not be so distant.

Dietary lipid composition modifies intestinal morphology and nutrient transport in young rats

BACKGROUND

Varying lipid content of the diet of pregnant and nursing dams results in alterations in sugar and lipid uptake into the intestine of their suckling offspring. In this study, we wished to determine whether the same alterations in dietary lipid result in adaptation of intestinal transport in postweaning rats.

METHODS

During nursing, the dams were fed the same diet that their offspring were fed for 3 more weeks after weaning. These semipurified diets contained: 1) 15.8% of total fatty acids (w/w) as 18:2n-6 and an n6/n3 ratio of 7.3:1; 2) a diet with 17.6% of total fatty acids as 18:2n-6 and an n6/n3 ratio of 4:1; 3) a diet with 16.2% of total fatty acids as 18:2n-6 and 1.2% arachidonic acid (AA); 4) a diet with 16.8% of total fatty acids at 18:2n-6, 1.2% AA and 0.7% docosahexaenoic acid (DHA); and 5) a diet with 16.0% of total fatty acids as 18:2n-6 and 0.7% as DHA. The in vitro uptake of D-glucose, D-fructose, medium- or long-chain fatty acids and cholesterol was assessed in 6-week-old rats.

RESULTS

Feeding AA increased the Vmax for jejunal and ileal uptake of glucose, compared with the high n6/n3 diet. This effect was prevented by adding DHA to the AA diet. The low n6/n3 fatty acid ratio diet decreased uptake of fructose as compared with the high n6/n3 diet, and the increased uptake of fructose with DHA was prevented by adding AA. The incremental change in free energy associated with uptake of medium chain-length fatty acids was lower in the jejunum of animals fed AA plus DHA as compared with the other diet groups. Jejunal uptake of 18:0 was lower for animals fed DHA or AA plus DHA, as compared with AA alone; ileal rate of uptake of long-chain fatty acids was unaffected by diet.

CONCLUSIONS

The intestine of young rats modifies its intestinal morphology and adapts its nutrient transport in response to variations in dietary lipids. In postweaning rats, the potentially undesirable effect of one fatty acid on nutrient uptake may be countered by adding a select second fatty acid to the diet.

Submucosal hemorrhage of the esophagus associated with endoscopy in a patient with cervical osteophytes

Submucosal hemorrhage of the esophagus is an uncommon complication of endoscopy. It has a characteristic appearance and is most likely to occur in patients with cervical osteophytes. It is important to recognize the lesion so that unnecessary biopsies are not taken and other investigations are limited.

Maximising the world wide web for high quality educational and clinical support to health and medical professionals in rural areas

Attracting and retaining medical and allied health professionals to rural and remote regions is a perennial problem, world-wide. It is exacerbated by the associated problem of providing high quality, cost-effective educational and clinical support to health professionals and trainees located in such areas. The world wide web is being used as a tool to address these twin problems to provide a means of communication, interaction and educational and clinical support to geographically dispersed and isolated pools of users. An interactive electronic notice board has been developed as a clinical problems' discussion forum to act as a venue for critical debate about clinical issues and to provide a searchable archive of information to assist in the management of clinical problems. A description of the forum will demonstrate the potential of the world wide web as a learning and a clinical support tool.

Serious hemorrhage complicating diagnostic abdominal paracentesis

We describe two patients awaiting orthoptic liver transplantation in whom diagnostic paracentesis for the diagnosis of spontaneous bacterial peritonitis led to major hemorrhage. Accordingly, we advise caution in patients such as ours, particularly if the prothrombin time or partial thromboplastin time is more than twice the control value.

Serum levels of interleukins 8 and 10, interferon gamma, granulocyte-macrophage colony stimulating factor and soluble CD23 in patients with primary sclerosing cholangitis

The presence of auto-antibodies and hypergammaglobulinaemia in patients with primary sclerosing cholangitis (PSC) suggest an overactive humoral immune system. Serum cytokines, measured using in-house double monoclonal sandwich ELISA, were used to assess the state of cellular and humoral immunity in this condition by comparison with sex and age matched normal controls and patients with alcoholic cirrhosis (AC). Soluble CD23 (sCD23) as a marker of humoral immunity was significantly elevated in PSC (N = 31) relative to patients with AC (N = 12) and the control group (N = 20) (P < 0.0001 and P < 0.001 respectively). Serum interleukin (IL) 10, as an anti-inflammatory cytokine and IL8, as a marker of neutrophil activation were significantly elevated in patients with PSC relative to those with AC and the controls (P < 0.001 and P < 0.05 respectively). Interferon gamma, as a marker of cellular immunity, and granulocyte-macrophage colony stimulating factor, a marker of monocyte/macrophage function were similar in all the groups. Cytokines and sCD23 were no different between patients with AC and the control group. While more than two thirds of the patients with PSC were positive for ANCA, there was no correlation between the presence of ANCA or ANCA titre and serum levels of either IL8, IL10 and sCD23. These results suggest exaggerated humoral immunity in PSC. The raised levels of IL10 and IL8 in PSC are discussed in the context of inflammatory bowel disease and liver dysfunction.

Psychological factors predicting nausea and vomiting in breast cancer patients on chemotherapy

A series of 100 breast cancer patients were included in a study to test the hypothesis that incidence of anticipatory nausea and vomiting during chemotherapy and towards the end of a patient's course of treatment is influenced by patient expectation, anxiety level and coping response. The role of psychological factors in postinfusional nausea and vomiting was also examined. Incidence of postinfusional and anticipatory nausea was high overall, with vomiting less frequently reported; 43% of patients reported nausea or vomiting before treatment at some stage over their chemotherapy cycles and 77% reported post-treatment symptoms. Anticipatory nausea was described by 47% of those experiencing it as being of moderate or severe intensity at some point throughout chemotherapy. Postinfusional side-effects were more intense; 21 and 10 patients, respectively, described severe or very severe levels as occurring at some point during their treatment. The majority of patients experiencing postinfusional symptoms indicated that these persisted for more than 24 h and were worse a day or two after chemotherapy administration. Incidence of anticipatory nausea or vomiting was found to relate directly to experience of nausea or vomiting during preceding cycles. Psychological variables were associated with symptoms of anticipatory nausea mid-treatment, but not with postinfusional symptoms. In particular, trait anxiety and a baseline expectation that nausea would be experienced during treatment were predictive in a multivariate model. Despite this, the overwhelming factor influencing ANV and PNV both mid- and towards the end of treatment was that of previous experience of the symptoms at earlier courses.

Oxidative stress and antioxidants in intestinal disease

Oxidative injury caused by free radicals is an important cause of tissue injury now recognized to occur in inflammation, ischemia and by the action of xenobiotics. It is also recognized to induce gene mutation and promote carcinogenesis. In this review the general concept of nett free radical injury counterbalanced by antioxidants is discussed as oxidative stress. The role of oxidative stress in intestinal ischemia, radiation enteritis, inflammatory bowel disease and the promotion of gastric and colorectal cancer is discussed. The data for the role of oxidative stress in the pathogenesis of ischemic, inflammatory and radiation induced disease are strong, but interventional studies with antioxidants have shown only weak beneficial effects in the above diseases. Therefore the role of antioxidants in the therapy of gastrointestinal diseases remains controversial and should be the subject of controlled trials.

Sleep and psychological disturbance in nocturnal asthma

Subjective and objective sleep disturbance was studied in children with nocturnal asthma. Relations between such disturbance and daytime psychological function were also explored, including possible changes in learning and behaviour associated with improvements in nocturnal asthma and sleep. Assessments included home polysomnography, parental questionnaires concerning sleep disturbance, behaviour, and mood and cognitive testing. Compared with matched controls, children with asthma had significantly more disturbed sleep, tended to have more psychological problems, and they performed less well on some tests of memory and concentration. In general, improvement of nocturnal asthma symptoms by changes in treatment was followed by improvement in sleep and psychological function in subsequent weeks. The effects of asthma on sleep and the possible psychological consequences are important aspects of overall care.