High plasma levels of pro-NT are associated with increased colon cancer risk

Emerging data supports a potential role of neurotensin (NT) in the development of obesity, obesity-associated comorbidities, and certain cancers. The association of NT with colon cancer risk has not been explicitly explored. We determined plasma levels of pro-NT, a stable NT precursor fragment, in 223 incident colon cancer patients and 223 age-, gender-, BMI-matched population controls participating in a population-based case-control study of colon cancer. On average, the cases have significantly higher levels of pro-NT than the controls (median = 205.6 pmol/L vs 183.1 pmol/L, respectively; P = 0.02). Multivariate logistic regression models, adjusted for age, gender, BMI, family history of colorectal cancer, smoking, diabetes mellitus, alcohol, and non-steroidal anti-inflammatory drugs use, show statistically significant risk associations: for continuous measure of pro-NT, the OR estimate was 1.30 (95% CI =1.03-1.64; P = 0.026) for each increment of 175 pmol/L; for dichotomized measure of pro-NT, the OR estimate was 1.75 (95% CI = 1.12-2.74; P = 0.025) for those in the top quartile comparing to the other participants. Our results support circulating levels of pro-NT as a novel risk biomarker for colon cancer.

Functional Characterization of Human ProNGF and NGF Mutants: Identification of NGF P61SR100E as a "Painless" Lead Investigational Candidate for Therapeutic Applications

Background

Nerve Growth Factor (NGF) holds a great therapeutic promise for Alzheimer's disease, diabetic neuropathies, ophthalmic diseases, dermatological ulcers. However, the necessity for systemic delivery has hampered the clinical applications of NGF due to its potent pro-nociceptive action. A “painless” human NGF (hNGF R100E) mutant has been engineered. It has equal neurotrophic potency to hNGF but a lower nociceptive activity. We previously described and characterized the neurotrophic and nociceptive properties also of the hNGF P61S and P61SR100E mutants, selectively detectable against wild type hNGF. However, the reduced pain-sensitizing potency of the “painless” hNGF mutants has not been quantified.

Objectives and Results

Aiming at the therapeutic application of the “painless” hNGF mutants, we report on the comparative functional characterization of the precursor and mature forms of the mutants hNGF R100E and hNGF P61SR100E as therapeutic candidates, also in comparison to wild type hNGF and to hNGF P61S. The mutants were assessed by a number of biochemical, biophysical methods and assayed by cellular assays. Moreover, a highly sensitive ELISA for the detection of the P61S-tagged mutants in biological samples has been developed. Finally, we explored the pro-nociceptive effects elicited by hNGF mutants in vivo, demonstrating an expanded therapeutic window with a ten-fold increase in potency.

Conclusions

This structure-activity relationship study has led to validate the concept of developing painless NGF as a therapeutic, targeting the NGF receptor system and supporting the choice of hNGF P61S R100E as the best candidate to advance in clinical development. Moreover, this study contributes to the identification of the molecular determinants modulating the properties of the hNGF “painless” mutants.

Prandial subcutaneous injections of glucagon-like peptide-1 cause weight loss in obese human subjects

Recombinant glucagon-like peptide-1 (7–36)amide (rGLP-1) was recently shown to cause significant weight loss in type 2 diabetics when administered for 6 weeks as a continuous subcutaneous infusion. The mechanisms responsible for the weight loss are not clarified. In the present study, rGLP-1 was given for 5d by prandial subcutaneous injections (PSI) (76nmol 30min before meals, four times daily; a total of 302·4nmol/24h) or by continuous subcutaneous infusion (CSI) (12·7nmol/h; a total of 304·8nmol/24h). This was performed in nineteen healthy obese subjects (mean age 44·2 (sem 2·5) years; BMI 39·0 (sem 1·2)kg/m2) in a prospective randomised, double-blind, placebo-controlled, cross-over study. Compared with the placebo, rGLP-1 administered as PSI and by CSI generated a 15% reduction in mean food intake per meal (P=0·02) after 5d treatment. A weight loss of 0·55 (sem 0·2) kg (P<0·05) was registered after 5d with PSI of rGLP-1. Gastric emptying rate was reduced during both PSI (P<0·001) and CSI (P<0·05) treatment, but more rapidly and to a greater extent with PSI of rGLP-1. To conclude, a 5d treatment of rGLP-1 at high doses by PSI, but not CSI, promptly slowed gastric emptying as a probable mechanism of action of increased satiety, decreased hunger and, hence, reduced food intake with an ensuing weight loss.

Glucagon-like peptide 1 and its derivatives in the treatment of diabetes

Glucagon-like peptide 1 (GLP-1) was discovered as an insulinotropic gut hormone, suggesting a physiological role as an incretin hormone, i.e., being responsible, in part, for the higher insulin secretory response after oral as compared to intravenous glucose administration. This difference, the incretin effect, is partially lost in patients with Type 2 diabetes. The actions of GLP-1 include (a) a stimulation of insulin secretion in a glucose-dependent manner, (b) a suppression of glucagon, (c) a reduction in appetite and food intake, (d) a deceleration of gastric emptying, (e) a stimulation of beta-cell neogenesis, growth and differentiation in animal and tissue culture experiments, and (f) an in vitro inhibition of beta-cell apoptosis induced by different toxins. Intravenous GLP-1 can normalize and subcutaneous GLP-1 can significantly lower plasma glucose in the majority of patients with Type 2 diabetes. GLP-1 itself, however, is inactivated rapidly in vivo and thus does not appear to be useful as a therapeutic agent in the long-term treatment of Type 2 diabetes. Other agents acting on GLP-1 receptors have been found (like exendin-4) or developed as GLP-1 derivatives (like liraglutide or GLP-1/CJC-1131). Clinical trials with exenatide (two injections per day) and liraglutide (one injection per day) have shown reductions in glucose concentrations and HbA1c by more than 1%, associated with moderate weight loss (2-3 kg), but also some nausea and, rarely, vomiting. It is hoped that this new class of drugs interacting with the GLP-1 or other incretin receptors, the so-called "incretin mimetics", will broaden our armamentarium of antidiabetic medications in the nearest future.

Unique characteristics of the geriatric diabetic population and the role for therapeutic strategies that enhance glucagon-like peptide-1 activity

PURPOSE OF REVIEW

Care for elderly diabetic patients poses a unique clinical challenge. This review highlights distinct aspects of the pathophysiology and the risks for secondary complications in the geriatric diabetic population. Based on these considerations, we discuss emerging therapeutic options based on the actions of the incretin hormone glucagon-like peptide (GLP)-1, which may be ideal for achieving glycemic control in the elderly diabetic patient.

RECENT FINDINGS

Aging is associated with diminished capacity of pancreatic beta-cells to respond to glucose. This functional decline in beta-cell insulin secretion is a major contributor to the development of diabetes in the older patient. In addition, elderly diabetics suffer from a broader range of diabetic complications than do younger diabetics, warranting aggressive glycemic control. GLP-1 is known to improve beta-cell insulin secretion, increase beta-cell mass, and suppress glucagon secretion. Recent studies investigating improved GLP-1 activity have yielded promising results, with improved glycemic control in elderly patients with type 2 diabetes and without significant risk for hypoglycemia.

SUMMARY

Elderly diabetics are a growing subset of the type 2 diabetic population with unique pathophysiologic characteristics and diabetic risk profiles. Therapeutic strategies that incorporate enhancement of GLP-1 action on beta-cells to improve beta-cell insulin secretion and glycemic control may be ideal for this distinct population and should be validated with further long-term clinical studies.

Incretin Mimetics as Emerging Treatments for Type 2 Diabetes

OBJECTIVE:

To review the physiology, pharmacology, and clinical efficacy of glucagon-like peptide (GLP-1) and the incretin mimetics exenatide and liraglutide in clinical studies.

DATA SOURCES:

Primary literature obtained via MEDLINE (1966–April 2004) and International Pharmaceutical Abstracts (1970–April 2004) searches; abstracts obtained from meeting sources and manufacturers.

STUDY SELECTION AND DATA EXTRACTION:

All English-language studies and abstracts evaluating GLP-1, exenatide, and liraglutide in the treatment of patients with type 2 diabetes were reviewed. Data from animal studies were also included if human data were not available. Primary and review articles related to the physiology, development, and evaluation of GLP-1s were reviewed.

DATA SYNTHESIS:

GLP-1, exenatide (exendin-4, AC2993), and liraglutide (NN2211) are incretin mimetics that have been shown in human studies to be an effective treatment to improve glycemic control in patients with type 2 diabetes. Mechanisms by which these compounds improve glycemic control include enhancing glucose-dependent pancreatic secretion of insulin in response to nutrient intake, inhibiting glucagon secretion, delaying gastric emptying, and promoting early satiety. GLP-1 has been shown to promote pancreatic progenitor cell differentiation and improve β-cell function and lifespan. Reported adverse effects of exenatide and liraglutide include nausea, vomiting, and transient headache, as well as increased risk of hypoglycemia when used with sulfonylureas.

CONCLUSIONS:

Clinical studies show that GLP-1, exenatide, and liraglutide improve glycemic control for patients with type 2 diabetes through unique mechanisms not available with current pharmaceutical products. Ongoing Phase III studies will help to further position these compounds as treatment options for patients with type 2 diabetes.

Effects of glucagon-like peptide-1 on endothelial function in type 2 diabetes patients with stable coronary artery disease

GLP-1 stimulates insulin secretion, suppresses glucagon secretion, delays gastric emptying, and inhibits small bowel motility, all actions contributing to the anti-diabetogenic peptide effect. Endothelial dysfunction is strongly associated with insulin resistance and type 2 diabetes mellitus and may cause the angiopathy typifying this debilitating disease. Therefore, interventions affecting both endothelial dysfunction and insulin resistance may prove useful in improving survival in type 2 diabetes patients. We investigated GLP-1's effect on endothelial function and insulin sensitivity (S(I)) in two groups: 1) 12 type 2 diabetes patients with stable coronary artery disease and 2) 10 healthy subjects with normal endothelial function and S(I). Subjects underwent infusion of recombinant GLP-1 or saline in a random crossover study. Endothelial function was measured by postischemic FMD of brachial artery, using ultrasonography. S(I) [in (10(-4) dl.kg(-1).min(-1))/(muU/ml)] was measured by hyperinsulinemic isoglycemic clamp technique. In type 2 diabetic subjects, GLP-1 infusion significantly increased relative changes in brachial artery diameter from baseline FMD(%) (3.1 +/- 0.6 vs. 6.6 +/- 1.0%, P < 0.05), with no significant effects on S(I) (4.5 +/- 0.8 vs. 5.2 +/- 0.9, P = NS). In healthy subjects, GLP-1 infusion affected neither FMD(%) (11.9 +/- 0.9 vs. 10.3 +/- 1.0%, P = NS) nor S(I) (14.8 +/- 1.8 vs. 11.6 +/- 2.0, P = NS). We conclude that GLP-1 improves endothelial dysfunction but not insulin resistance in type 2 diabetic patients with coronary heart disease. This beneficial vascular effect of GLP-1 adds yet another salutary property of the peptide useful in diabetes treatment.

Heat denaturation affects the ProDer p 1 IgE reactivity and downregulates the development of the specific allergic response

BACKGROUND

Modified allergens with reduced IgE-binding activity represent an elegant approach to circumvent the risk of anaphylactic reactions in allergen-specific immunotherapy.

OBJECTIVE

The current work investigated the effect of heat denaturation on the allergenic properties of recombinant ProDer p 1, a precursor form of the major house dust mite allergen Der p 1.

METHODS

The IgE reactivity was estimated by direct and competition ELISA. The immunogenicity of heat-denatured ProDer p 1 was evaluated in naive and Der p 1-allergic mice.

RESULTS

Heat denaturation in reducing conditions drastically reduced the in vitro ProDer p 1 IgE reactivity toward human allergic sera. In naive mice, heat-denatured ProDer p 1 generated mixed T(H)1-T(H)2 responses characterized by the absence of specific IgE with concomitant rise in specific IgG2a titers and the presence of IL-5 and IFN-gamma in splenocyte cultures. In contrast, natural Der p 1 or native ProDer p 1 induced typical strict T(H)2-biased allergic responses with strong IgG1 and IgE titers, whereas spleen cells exhibited only high IL-5 secretion. Moreover, native or heat-denatured ProDer p 1 vaccinations prevented airway eosinophil infiltrations after challenge. Although native or heat-treated ProDer p 1 adjuvanted with SBAS1b induced mixed T(H)1-T(H)2 responses in allergic mice, heat-denatured ProDer p 1, compared with native ProDer p 1, proved to be more effective in redirecting the T(H)2-allergic response toward T(H)1.

CONCLUSION

Taken together, our results suggest that variants of Der p 1 with reduced IgE-binding reactivity could represent hypoallergenic molecules suitable for allergen-specific immunotherapy.

[Advances in safety studies of soil Bt toxin proteins released from transgenic Bt crops]

Commercialized transgenic Bt (Bacillus thuringiensis) crops are permitted for field growth in a large scale, which leads to significant issues of ecological risk assessment in soil ecosystem. In this paper, some general safety problems involving in the soil Bt active toxins released from insect-resistant transgenic Bt crops in the forms of plant residues, root exudates and pollens were reviewed, including their adsorption by soil active-particles, their insecticidal activity, persistence, and biodegradation by soil microbes, and their effects on soil organisms.

Effects of 3 months of continuous subcutaneous administration of glucagon-like peptide 1 in elderly patients with type 2 diabetes

OBJECTIVE

Glucagon-like peptide 1 (GLP-1) is an insulinotropic gut hormone that, when given exogenously, may be a useful agent in the treatment of type 2 diabetes. We conducted a 3-month trial to determine the efficacy and safety of GLP-1 in elderly diabetic patients.

RESEARCH DESIGN AND METHODS

A total of 16 patients with type 2 diabetes who were being treated with oral hypoglycemic agents were enrolled. Eight patients (aged 75 +/- 2 years, BMI 27 +/- 1 kg/m(2)) remained on usual glucose-lowering therapy and eight patients (aged 73 +/- 1 years, BMI 27 +/- 1 kg/m(2)), after discontinuing hypoglycemic medications, received GLP-1 delivered by continuous subcutaneous infusion for 12 weeks. The maximum dose was 120 pmol x kg(-1). h(-1). Patients recorded their capillary blood glucose (CBG) levels (four times per day, 3 days per week) and whenever they perceived hypoglycemic symptoms. The primary end points were HbA(1c) and CBG determinations. Additionally, changes in beta-cell sensitivity to glucose, peripheral tissue sensitivity to insulin, and changes in plasma ghrelin levels were examined.

RESULTS

HbA(1c) levels (7.1%) and body weight were equally maintained in both groups. The usual treatment group had a total of 87 CBG measurements of <or=3.6 mmol/l during the study, and only 1 such measurement (3.5 mmol/l) was recorded in the GLP-1 group. Infusion of GLP-1 enhanced glucose-induced insulin secretion (pre: 119 +/- 21; post: 202 +/- 51 pmol/l; P < 0.05) and insulin-mediated glucose disposal (pre: 29.8 +/- 3.3; post: 35.9 +/- 2.3 micromol x kg(-1 x min(-1); P < 0.01). No effect of GLP-1 treatment was seen on the fasting plasma ghrelin levels. Although plasma ghrelin levels decreased during both portions of the clamp, a drug effect was not present.

CONCLUSIONS

A GLP-1 compound is a promising therapeutic option for elderly diabetic patients.

New vaccination strategies for low- and non-responders to hepatitis B vaccine

The currently available recombinant hepatitis B vaccines are safe, efficacious and immunogenic. Nevertheless, a high rate of low- and nonresponsiveness to the current vaccine poses a problem since this group remains susceptible to infection with hepatitis B virus. Efforts are underway to develop new vaccines and strategies to enhance seroprotection rates. One possibility under investigation is the low-dose intradermal administration of vaccine since the immune system is well represented in both the epidermis and the dermis. Despite encouraging results concerning the immunogenicity in previous non-responders, the main difficulty is the technique of administration and unacceptable local adverse effects. Promising data have emerged from clinical trials evaluating the immunogenicity of new recombinant vaccines containing the complete pre-S1 and pre-S2 regions of HbsAg and, more recently, of novel adjuvanted hepatitis B vaccines. Future approaches include DNA vaccination and expression of HbsAg determinants in live recombinant vectors.

Glucagon-like peptide-1 infusion must be maintained for 24 h/day to obtain acceptable glycemia in type 2 diabetic patients who are poorly controlled on sulphonylurea treatment

OBJECTIVE

To assess the efficacy and safety of glucagon-like peptide-1 (GLP-1) on the plasma glucose level when given as a continuous infusion for either 16 or 24 h per day to type 2 diabetic patients who were poorly controlled on sulfonylurea treatment.

RESEARCH DESIGN AND METHODS

This single-center, randomized, parallel, double-blind, placebo-controlled trial was conducted in 40 hospitalized patients who were randomized to receive infusions of either placebo or GLP-1 4 or 8 ng. kg(-1). min(-1) for either 16 or 24 h per day for 7 days. At predetermined intervals, 24-h profiles of glucose, glucagon, and insulin were measured. Adverse events and clinical chemistry and hematology were recorded.

RESULTS

For all active treatment groups, the change in average glucose (area under the curve [AUC] for day 7 minus AUC for day 0 divided by 24 h) was statistically significantly different from placebo (P < or = 0.001). The GLP-1 8 ng. kg(-1). min(-1) dose given for 24 h was more efficacious than any of the other doses (P < or = 0.05). Nocturnal and fasting plasma glucose levels at day 7 were greater in the 16-h groups compared with the 24-h groups (P < or = 0.05). Insulin AUC did not show any treatment effect for any of the treatment groups when change was assessed from day 0 to day 7. However, for the 16-h groups, the pattern of the insulin profiles changed; the insulin profiles were considerably higher during the initial 3-4 h after restart of the GLP-1 infusion on day 7, although there was a tendency for insulin levels to decrease during the afternoon and evening. Glucagon AUC decreased significantly for all active treatment groups compared with placebo. GLP-1 was generally well tolerated.

CONCLUSIONS

This study demonstrated that GLP-1 should be given continuously to obtain the most optimal glycemic control. Because of the short plasma half-life of native GLP-1, long-acting derivatives should be developed to make GLP-1 treatment clinically relevant.

A novel hyperglycaemic clamp for characterization of islet function in humans: assessment of three different secretagogues, maximal insulin response and reproducibility

BACKGROUND

Characterization of beta-cell function in humans is essential for identifying genetic defects involved in abnormal insulin secretion and the pathogenesis of type 2 diabetes.

MATERIALS AND METHODS

We designed a novel test assessing plasma insulin and C-peptide in response to 3 different secretagogues. Seven lean, healthy volunteers twice underwent a 200 min hyperglycaemic clamp (10 mmol L-1) with administration of GLP-1 (1.5 pmol. kg-1. min-1) starting at 120 min and an arginine bolus at 180 min. We determined glucose-induced first and second-phase insulin secretion, GLP-1-stimulated insulin secretion, arginine-stimulated insulin response (increase above prestimulus, DeltaIarg) and the maximal, i. e. highest absolute, insulin concentration (Imax). Insulin sensitivity was assessed during second-phase hyperglycaemia. On a third occasion 6 subjects additionally received an arginine bolus at > 25 mM blood glucose, a test hitherto claimed to provoke maximal insulin secretion.

RESULTS

Insulin levels increased from 46 +/- 11 pM to 566 +/- 202 pM at 120 min, to 5104 +/- 1179 pM at 180 min and to maximally 8361 +/- 1368 pM after arginine (all P < 0.001). The within subject coefficients of variation of the different secretion parameters ranged from 10 +/- 3% to 16 +/- 6%. Except for second-phase which failed to correlate significantly with DeltaIarg (r = 0.52, P = 0.23) and Imax (r = 0.75, P = 0.053) all phases of insulin secretion correlated with one another. The insulin concentration after the arginine bolus at > 25 mM glucose (n = 6) was 2773 +/- 855 pM vs. 7562 +/- 1168 pM for Imax (P = 0.003).

CONCLUSION

This novel insulin secretion test elicits a distinct pattern of plasma insulin concentrations in response to the secretagogues glucose, GLP-1 and arginine and is highly reproducible and can be used for differential characterization of islet function.

Gonadotropin-releasing hormone agonists administration in polycystic ovary syndrome. Effects on bone mass

Women with amenorrhea and polycystic ovaries (PCO) seem to present a relative degree of protection against bone loss caused by hypoestrogenism. We treated 20 patients affected by polycystic ovary syndrome (PCOS) with a gonadotropin-releasing hormone agonist (GnRH-a) for 6 months. After treatment mean bone mineral density (BMD) significantly decreased. We concluded that patients with PCOS have to be considered at risk of developing osteopenia when treated with GnRH-a. The relative protection against osteoporosis, that is present in amenorrheic patients with PCO, might be attributed to the characteristics of amenorrhea in these patients.

Near-normalisation of diurnal glucose concentrations by continuous administration of glucagon-like peptide-1 (GLP-1) in subjects with NIDDM

The gut hormone, glucagon-like peptide-1 (GLP-1) is a potent insulin secretogogue with potential as a therapy for non-insulin-dependent diabetes mellitus (NIDDM). GLP-1 has been shown to reduce glucose concentrations, both basally, and, independently, in response to a single meal. For it to be an effective treatment, it would need to be administered as a long-acting therapy, but this might not be feasible due to the profound delay in gastric emptying induced by GLP-1. In order to assess the feasibility and efficacy of continuous administration of GLP-1 in NIDDM, we determined the effects of continuous intravenous infusion of GLP-1 (7-36) amide, from 22.00-17.00 hours, on glucose and insulin concentrations overnight and in response to three standard meals, in eight subjects with NIDDM. These were compared with responses to 0.9% NaCl infusion and responses in six non-diabetic control subjects who were not receiving GLP-1. Effects of beta-cell function were assessed in the basal state using homeostasis model assessment (HOMA) and in the postprandial state by dividing incremental insulin responses to breakfast by incremental glucose responses. To assess possible clinical benefit from priming of beta cells by GLP-1 given overnight only, a third study assessed the effect of GLP-1 given from 22.00-07.30 hours on subsequent glucose responses the next day. Continuous GLP-1 infusion markedly reduced overnight glucose concentrations (mean from 24.00-08.00 hours) from median (range) 7.8 (6.1-13.8) to 5.1 (4.0-9.2) mmol/l (p < 0.02), not significantly different from control subjects, 5.6 (5.0-5.8) mmol/l. Daytime glucose concentrations (mean from 08.00-17.00 hours) were reduced from 11.0 (9.3-16.4) to 7.6 (4.9-11.5) mmol/l (p < 0.02), not significantly different from control subjects, 6.7 (6.5-7.0) mmol/l. GLP-1 improved beta-cell function in the basal state from 62 (13-102) to 116 (46-180) %beta (p < 0.02) and following breakfast from 57 (19-185) to 113 (31-494) pmol/mmol (p < 0.02). GLP-1 only given overnight did not improve the glucose responses to meals the next day. In conclusion, continuous infusion of GLP-1 markedly reduced diurnal glucose concentrations, suggesting that continuous GLP-1 administration may be as useful therapy in NIDDM.

[Factors with insulin-like effects: IGF-I and GLP-1]

In the submitted review the author discusses two substances secreted into the circulation which can similarly as insulin lower the blood sugar level. These substances are IGF-I (insulin-like growth factor I) and GLP (glucagon-like peptide). While in case of the former it is not certain whether it participates in the glucose homeostasis, this is beyond doubt in the latter. IGF-I prepared by the recombinant technique can be used therapeutically in cases of insulin resistance caused by a receptor or postreceptor disorder, because it may act via its own receptor. Side-effects after larger doses are a problem. GLP-1, the use of which would be useful in type 2 diabetics as it stimulates insulin secretion, is not used so far in therapy because hitherto prepared preparations have a very short period of a effectiveness.

A prime-boost approach to HIV preventive vaccine using a recombinant canarypox virus expressing glycoprotein 160 (MN) followed by a recombinant glycoprotein 160 (MN/LAI). The AGIS Group, and l'Agence Nationale de Recherche sur le SIDA

The safety and the immunogenicity of a recombinant canarypox live vector expressing the human immunodeficiency virus type 1 (HIV-1) gp160 gene from the MN isolate, ALVAC-HIV (vCP125), followed by booster injections of a soluble recombinant hybrid envelope glycoprotein MN/LAI (rgp160), were evaluated in vaccinia-immune, healthy adults at low risk for acquiring HIV-1 infection. Volunteers (n = 20) received vCP125 (10(6) TCID50) at 0 and 1 month, followed randomly by rgp160 formulated in alum or in Freund's incomplete adjuvant (FIA) at 3 and 6 months. Local and systemic reactions were mild or moderate and resolved within the first 72 hr after immunization. No significant biological changes in routine tests were observed in any volunteer. Two injections of vCP125 did not elicit antibodies. Neutralizing antibodies (NA) against the HIV-1 MN isolate were detected in 65 and 90% of the subjects after the first and the second rgp 160 booster injections, respectively. Six months after the last boost, only 55% were still positive. Seven of 14 sera with the highest NA titers against MN weakly cross-neutralized the HIV-1 SF2 isolate; none had NA against the HIV-1 LAI or against a North American primary isolate. Specific lymphocyte T cell proliferation to rgp 160 was detected in 25% of the subjects after vCP125 and in all subjects after the first booster injection and 12 months after the first injection. An envelope-specific cytotoxic lymphocyte activity was found in 39% of the volunteers and characterized for some of them as CD3+, CD8+, MHC class I restricted. The adjuvant formulation did not influence significantly the immune responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Dephosphorylation of the retinoblastoma gene product induced by differentiation and its relevancy to growth inhibition in normal human keratinocytes

The retinoblastoma gene product (pRB) is a tumor suppressor gene product. Recently, it has been shown that the dephosphorylation of pRB leads a variety of cells into G1/G0 arrest. Keratinocytes were grown in serum-free MCDB 153 medium containing 0.1 mM Ca2+, followed by addition of Ca2+ to 1.8 mM (calcium switch). Under-phosphorylated pRB band appeared at 48 h and increased up to 72 h after calcium switch. S phase cells decreased at 48 and 72 h in a time-dependent manner. In contrast, the number of involucrin positive cells, differentiated cells, increased even at 24 h, preceding the dephosphorylation of pRB and continued to increase up to 72 h. These results indicate that the dephosphorylation of pRB is closely related to growth inhibition of human keratinocytes associated with differentiation.

Safety and immunogenicity of a fully glycosylated recombinant gp160 human immunodeficiency virus type 1 vaccine in subjects at low risk of infection. National Institute of Allergy and Infectious Diseases AIDS Vaccine Evaluation Group Network

Recombinant gp160 derived from human immunodeficiency virus type 1 (HIV-1)IIIB and produced in mammalian tissue culture cells using a vaccinia virus expression system (rgp160-mam) was evaluated as a vaccine in combination with alum and deoxycholate adjuvant. Sixty low-risk, uninfected subjects received 12.5 micrograms, 50.0 micrograms, or adjuvant control at 0, 1, 6, and 12 months in a randomized, double-blind dose-escalation study. A single injection of 200 micrograms of vaccine was given at 18 months in an open study to 9 vaccines who had received 50 micrograms. The vaccine was safe. Six of 16 subjects receiving 50 micrograms developed neutralizing antibody to HIV-1IIIB. Seven of the 9 boosted with 200 micrograms of vaccine at 18 months developed neutralizing antibodies. Lymphocyte proliferation to rgp160-mam and baculovirus-derived rgp160 and rgp120 was induced in both groups (12.5 and 50.0 micrograms) and appeared after the first dose. Further studies with higher doses of rgp160-mam and vaccines derived from other strains of HIV-1 are warranted.

Removal of gp160 induced bio-hazards for a safe AIDS vaccine candidate

In the first AIDS vaccine trial, immunizing preparations were based on HIV-1 Env protein (gp160). Immunogenic properties of gp160 which trigger both a humoral and cellular immune response have since justified its use in various vaccine programs, both past and present. Many reports however have underlined deleterious effects on the immune system--anti-HIV-1 enhanced antibodies, anti-CD4 autoantibodies, and inhibition of T cell activation by HIV-1--particularly associated with the Env protein. The present study shows that gp160 presented in a biologically inactivated but immunogenic form, as used in our trial, could avoid these complications. Bio-hazards associated with gp160 which indeed could be removed by appropriate treatment of the native protein, should be taken into consideration in AIDS vaccine programs.

A phase I evaluation of the safety and immunogenicity of vaccination with recombinant gp160 in patients with early human immunodeficiency virus infection. Military Medical Consortium for Applied Retroviral Research

BACKGROUND

Despite multiple antiviral humoral and cellular immune responses, infection with the human immunodeficiency virus (HIV) results in a progressively debilitating disease. We hypothesized that a more effective immune response could be generated by post-infection vaccination with HIV-specific antigens.

METHODS

We performed a phase I trial of the safety and immunogenicity of a vaccine prepared from molecularly cloned envelope protein, gp160, in 30 volunteer subjects with HIV infection in Walter Reed stage 1 or 2. The vaccine was administered either on days 0, 30, and 120 or on days 0, 30, 60, 120, 150, and 180. HIV-specific humoral and cellular immune responses were measured; local and systemic reactions to vaccination, including general measures of immune function, were monitored.

RESULTS

In 19 of the 30 subjects both humoral and cellular immunity to HIV envelope proteins increased in response to vaccination with gp160. Seroconversion to selected envelope epitopes was observed, as were new T-cell proliferative responses to gp160. Response was associated with the CD4 cell count determined before vaccination (13 of 16 subjects [81 percent] with greater than 600 cells per milliliter responded, as compared with 6 of 14 [43 percent] with less than or equal to 600 cells per milliliter; P = 0.07) and with the number of injections administered (87 percent of subjects randomly assigned to receive six injections responded, as compared with 40 percent of those assigned to three injections; P = 0.02). Local reactions at the site of injection were mild. There were no adverse systemic reactions, including diminution of general in vitro or in vivo cellular immune function. After 10 months of follow-up, the mean CD4 count had not decreased in the 19 subjects who responded, but it had decreased by 7.3 percent in the 11 who did not respond.

CONCLUSIONS

This gp160 vaccine is safe and immunogenic in volunteer patients with early HIV infection. Although it is too early to know whether this approach will be clinically useful, further scientific and therapeutic evaluation of HIV-specific vaccine therapy is warranted. Similar vaccines may prove to be effective for other chronic infections.