Highly sensitive ligand-binding assays in pre-clinical and clinical applications: immuno-PCR and other emerging techniques

Recombinant DNA technology and corresponding innovations in molecular biology, chemistry and medicine have led to novel therapeutic biomacromolecules as lead candidates in the pharmaceutical drug development pipelines. While monoclonal antibodies and other proteins provide therapeutic potential beyond the possibilities of small molecule drugs, the concomitant demand for supportive bioanalytical sample testing creates multiple novel challenges. For example, intact macromolecules can usually not be quantified by mass-spectrometry without enzymatic digestion and isotopically labeled internal standards are costly and/or difficult to prepare. Classical ELISA-type immunoassays, on the other hand, often lack the sensitivity required to obtain pharmacokinetics of low dosed drugs or pharmacodynamics of suitable biomarkers. Here we summarize emerging state-of-the-art ligand-binding assay technologies for pharmaceutical sample testing, which reveal enhanced analytical sensitivity over classical ELISA formats. We focus on immuno-PCR, which combines antibody specificity with the extremely sensitive detection of a tethered DNA marker by quantitative PCR, and alternative nucleic acid-based technologies as well as methods based on electrochemiluminescence or single-molecule counting. Using case studies, we discuss advantages and drawbacks of these methods for preclinical and clinical sample testing.

Emerging technologies to increase ligand binding assay sensitivity

Ligand binding assays (LBAs) have been the method of choice for protein analyte measurements for more than four decades. Over the years, LBA methods have improved in sensitivity and achieved larger dynamic ranges by using alternative detection systems and new technologies. As a consequence, the landscape and application of immunoassay platforms has changed dramatically. The introduction of bead-based methods, coupled with single molecule detection standardization and the ability to amplify assay signals, has improved the sensitivity of many immunoassays, in some cases by several logs of magnitude. Three promising immunoassay platforms are described in this article: Single Molecule Counting (SMC™) from Singulex Inc, Single Molecule Arrays (Simoa™) from Quanterix Corporation, and Immuno-PCR (Imperacer®) from Chimera Biotec GmbH. These platforms have the potential to significantly improve immunoassay sensitivity and thereby address the bioanalytical needs and challenges faced during biopharmaceutical drug development.

Evaluation of the efficacy and tolerability of acarbose in patients with diabetes mellitus : a postmarketing surveillance study

OBJECTIVE

The efficacy and tolerability of acarbose were examined in a postmarketing surveillance study of 27 803 patients with diabetes mellitus (26 044 were diagnosed as having type 2 diabetes) over a 12-week treatment period. PATIENTS AND M ethods: Overall efficacy data were reported for type 1 and type 2 diabetes, and a detailed data analysis was conducted for patients with type 2 diabetes. Tolerability was described for the total group. Of the type 2 diabetes patients, 37.6% were treated with diet only; 44.2% were additionally treated with sulphonylureas; 6.3% with metformin or metformin plus sulphonylurea; and 11.6% with insulin alone or in combination with oral treatment. The frequency of two or more concomitant diseases was 45.8% for all type 2 diabetes patients, and 62.4% in elderly patients (age >/=70 years).

RESULTS

In patients with type 2 diabetes, acarbose administration in addition to the existing treatment resulted in reductions in mean blood glucose levels (fasting 50 mg/dL, 1h post-prandial [pp] 60 mg/dL, 2h pp 56 mg/dL), glycosylated haemoglobin (HbA(1c) 1.3%; HbA(1) 1.6%) and bodyweight (1.5 kg). Results for type 1 diabetes patients were similar. No clinically relevant influence of age, body mass index or number of concomitant diseases on the results could be observed. Tolerability was good: 83% of patients had no adverse events, 13.7% reported flatulence, and 2.2% had at least one occurrence of diarrhoea. Hypoglycaemia was found in 0.07% of patients, mainly in combination with metformin or insulin. Tolerability was independent of patients' age. Laboratory investigations gave no indication of other adverse events.

CONCLUSION

This postmarketing surveillance study documents the therapeutic benefit and good tolerability and compliance of acarbose as mono- and combination therapy, even in elderly and multimorbid patients.

Environmental persistence of amphibian and reptilian ranaviruses

Ranaviruses infect fish, amphibians, and reptiles. The present study was conducted to compare the persistence of amphibian and reptilian ranaviruses in a pond habitat. The 4 viruses used in this study included 2 amphibian ranaviruses, Frog virus 3 (FV3, the type species of the genus Ranavirus) and an isolate from a frog, and 2 ranaviruses of reptilian origin (from a tortoise and from a gecko). A sandwich germ-carrier technique was used to study the persistence of these viruses in sterile and unsterile pond water (PW) and soil obtained from the bank of a pond. For each virus, virus-loaded carriers were placed in each of the 3 substrates, incubated at 4 and 20°C, and titrated at regular intervals. Serial data were analyzed using a linear regression model to calculate T-90 values (time required for 90% reduction in the virus titer). Resistance of the viruses to drying was also studied. All 4 viruses were resistant to drying. At 20°C, T-90 values of the viruses were 22 to 31 d in sterile PW and 22 to 34 d in unsterile PW. Inactivation of all 4 viruses in soil at this temperature appeared to be non-linear. T-90 values at 4°C were 102 to 182 d in sterile PW, 58 to 72 d in unsterile PW, and 30 to 48 d in soil. Viral persistence was highest in the sterile PW, followed by the unsterile PW, and was lowest in soil. There were no significant differences in the survival times between the amphibian and reptilian viruses. The results of the present study suggest that ranaviruses can survive for long periods of time in pond habitats at low temperatures.

Screening for cytochrome p450 reactivity by harnessing catalase as reporter enzyme

Cytochrome P450 enzymes are known to catalyze a variety of reactions that are difficult to perform by standard organic synthesis, such as the oxidation of unactivated C--C bonds. Cytochrome P450 enzymes can also be used in artificial systems in which organic peroxides act as cosubstrates. To find substrates that are converted by a certain P450 catalyst in the presence of an organic peroxide, various screening assays have been established, however, most of them are limited to one or only a few specific substrates. Here, we report a simple and rapid screening assay that works independently of the nature of the substrate and utilizes a previously undescribed reactivity of catalase as reporter enzyme. In an initial demonstration of this assay, we screened 180 enzyme/peroxide/substrate combinations for potential bioconversions. As shown by subsequent verification of the screening results with liquid chromatography/multistage mass spectrometry (LC/MS(n)), we were able to identify three new substrates for the enzyme CYP152A1 and at least two previously undescribed conversions by the enzyme CYP119.

Engineering and assaying of cytochrome P450 biocatalysts

Cytochrome P450s constitute a highly fascinating superfamily of enzymes which catalyze a broad range of reactions. They are essential for drug metabolism and promise industrial applications in biotechnology and biosensing. The constant search for cytochrome P450 enzymes with enhanced catalytic performances has generated a large body of research. This review will concentrate on two key aspects related to the identification and improvement of cytochrome P450 biocatalysts, namely the engineering and assaying of these enzymes. To this end, recent advances in cytochrome P450 development are reported and commonly used screening methods are surveyed.

Synthesis of covalent DNA-protein conjugates by expressed protein ligation

Semisynthetic DNA-protein conjugates are versatile tools for many applications in bioanalytics and nanobiotechnology. We here report a method based on expressed protein ligation (EPL) for the site-specific coupling of cysteine-modified DNA oligomers with recombinant intein-fusion proteins. The latter contain a C-terminal thioester, enabling the mild and highly specific reaction with N-terminal cysteine compounds. To conveniently couple commercially available DNA oligomers with cysteine groups a universal chemical modifier was developed, containing a protected cysteine and an amino-reactive N-hydroxysuccinimide group connected by a hexaethyleneglycol moiety. Using maltose-binding protein (MBP) and green fluorescent protein mutant EYFP as a model systems, we demonstrate the feasibility of this approach, as well as the integrity and functionality of the DNA-protein conjugates synthesized. We anticipate that our concept will enable many applications, such as the generation of large arrays of surface-bound, recombinant proteins assembled by means of DNA-directed immobilization.

Mushroom bodies and post-mating behaviors of Drosophila melanogaster females

After mating, Drosophila melanogaster females lay substantially more eggs and mate rarely. Central to these changes is Sex peptide (SP), a male peptide transferred into the female during copulation. Injected into virgins, SP induces the same post mating response as observed after mating. In this study we investigated the role of the mushroom body (MB) in the SP response system. The SP response of females with either chemically ablated or mutant MBs was analyzed. After injection of SP, females with chemically ablated MBs reduce their receptivity and increase their ovulation and oviposition to the level of females with intact MBs. Virgin females with ablated MBs, however, show a constitutively elevated oviposition rate. Hence in untreated females, MBs are not implicated in the SP-induced reduction of receptivity and increase of ovulation. However, they depress the oviposition rate of virgins. Thus, SP has two functions for oviposition: it de-represses the MB-dependent block on the egg laying activity of virgins and additionally stimulates oviposition. SP-injected mushroom body miniature (mbm) females lay fewer eggs, ovulate less frequently, and mate more often than wild-type females. A model of the putative role of MBs and the gene product of mbm in SP-induced oviposition is presented.

Mutational analysis of the repeated open reading frames, ORFs 63 and 70 and ORFs 64 and 69, of varicella-zoster virus

Varicella-zoster virus (VZV) open reading frame 63 (ORF63), located between nucleotides 110581 and 111417 in the internal repeat region, encodes a nuclear phosphoprotein which is homologous to herpes simplex virus type 1 (HSV-1) ICP22 and is duplicated in the terminal repeat region as ORF70 (nucleotides 118480 to 119316). We evaluated the role of ORFs 63 and 70 in VZV replication, using recombinant VZV cosmids and PCR-based mutagenesis to make single and dual deletions of these ORFs. VZV was recovered within 8 to 10 days when cosmids with single deletions were transfected into melanoma cells along with the three intact VZV cosmids. In contrast, VZV was not detected in transfections carried out with a dual deletion cosmid. Infectious virus was recovered when ORF63 was cloned into a nonnative AvrII site in this cosmid, confirming that failure to generate virus was due to the dual ORF63/70 deletion and that replication required at least one gene copy. This requirement may be related to our observation that ORF63 interacts directly with ORF62, the major immediate-early transactivating protein of VZV. ORF64 is located within the inverted repeat region between nucleotides 111565 and 112107; it has some homology to the HSV-1 Us10 gene and is duplicated as ORF69 (nucleotides 117790 to 118332). ORF64 and ORF69 were deleted individually or simultaneously using the VZV cosmid system. Single deletions of ORF64 or ORF69 yielded viral plaques with the same kinetics and morphology as viruses generated with the parental cosmids. The dual deletion of ORF64 and ORF69 was associated with an abnormal plaque phenotype characterized by very large, multinucleated syncytia. Finally, all of the deletion mutants that yielded recombinants retained infectivity for human T cells in vitro and replicated efficiently in human skin in the SCIDhu mouse model of VZV pathogenesis.

Interactions among structural proteins of varicella zoster virus

Varicella zoster virus tegument components include the regulatory proteins IE4, IE62, IE63 and the ORFI0 protein, a protein kinase (ORF47) and an abundant protein encoded in ORF9 which is the homolog of HSV VP22. The kinase is able to phosphorylate IE62 and the ORF9 protein specifically in viral particles. We show that interactions among these proteins are, at least in part, dependent on the presence or absence of phosphate groups and we suggest models for tegument formation and for its dissolution in the infected cell.

Drosophila transcription factor AP-2 in proboscis, leg and brain central complex development

We report loss- and gain-of-function analyses that identify essential roles in development for Drosophila transcription factor AP-2. A mutagenesis screen yielded 16 lethal point mutant alleles of dAP-2. Null mutants die as adults or late pupae with a reduced proboscis, severely shortened legs (~30% of normal length) lacking tarsal joints, and disruptions in the protocerebral central complex, a brain region critical for locomotion. Seven hypomorphic alleles constitute a phenotypic series yielding hemizygous adults with legs ranging from 40–95% of normal length. Hypomorphic alleles show additive effects with respect to leg length and viability; and several heteroallelic lines were established. Heteroallelic adults have moderately penetrant defects that include necrotic leg joints and ectopic growths (sometimes supernumerary antennae) invading medial eye territory. Several dAP-2 alleles with DNA binding domain missense mutations are null in hemizygotes but have dominant negative effects when paired with hypomorphic alleles. In wild-type leg primordia, dAP-2 is restricted to presumptive joints. Ectopic dAP-2 in leg discs can inhibit but not enhance leg elongation indicating that functions of dAP-2 in leg outgrowth are region restricted. In wing discs, ectopic dAP-2 cell autonomously transforms presumptive wing vein epithelium to ectopic sensory bristles, consistent with an instructive role in sensory organ development. These findings reveal multiple functions for dAP-2 during morphogenesis of feeding and locomotor appendages and their neural circuitry, and provide a new paradigm for understanding AP-2 family transcription factors.

Acarbose treatment does not change the habitual diet of patients with Type 2 diabetes mellitus. The Finnish Acargbos Study Group

AIMS

It has been speculated that acarbose treatment in patients with Type 2 diabetes mellitus might induce changes in diet as a result of its adverse gastrointestinal effects. The aim of this study was to determine whether poor metabolic control can be improved by acarbose, and whether this might be because the acarbose supplementation provokes changes in diet.

METHODS

Poorly controlled Type 2 diabetic patients treated with oral hypoglycaemic agents (OHA) were randomized into either acarbose (100 mg t.d.s.) or placebo treatment. The double-blind treatment lasted for 24 weeks. Four-day food diaries and blood samples for efficacy analysis were collected at 0, 4, 12, and 24 weeks. Thirty-six acarbose and 39 placebo-treated patients completed the trial and were included in the final analyses.

RESULTS

At 24 weeks the baseline adjusted means of fasting, 1 and 2-h postprandial blood glucose values were 9.3 vs. 10.5 (P=0.02), 11.6 vs. 14.5 (P<0.001) and 11.0 vs. 13.7 mmol/l (P<0.001) and HbA1 9.3% vs. 10.2% (P=0.002) in the acarbose and placebo groups, respectively. No significant differences in nutrient intakes between groups were observed. The energy intake and energy proportion of fat and carbohydrates remained unchanged in both groups.

CONCLUSIONS

Acarbose significantly improves metabolic control in Type 2 diabetic patients poorly controlled with oral hypoglycaemic agents. This effect seems not to be a result of concomitant involuntary dietary changes, since acarbose did not induce modifications in diet during the study.

Efficacy and safety of acarbose in patients with cystic fibrosis and impaired glucose tolerance

Impaired glucose tolerance (IGT) is an increasingly frequent complication of cystic fibrosis (CF). In CF patients, a fast postprandial rise in plasma glucose is typically followed by a delayed but prolonged insulin response. Patients may develop symptoms of both hyper- and hypoglycaemia. The alpha-glucosidase inhibitor, acarbose, delays the hydrolysis and subsequent absorption of ingested carbohydrates. The aim of this study was to investigate the efficacy of acarbose in CF patients with IGT. During a 2-week inpatient period for treatment of Pseudomonas infection, 12 CF patients with IGT were studied in a double-blinded, randomized crossover trial. Each patient received acarbose (50 mg t.i.d.) for 5 days and placebo for 5 days (days 3-8 and days 10-14, respectively). Glucose, insulin and C-peptide responses to a standardized nutritional load were measured at baseline and at the end of each study period (Days 2, 8 and 14). Treatment with acarbose was associated with significant reductions in the mean value, mean peak values and the area under the curve of plasma glucose, insulin and C-peptide, compared to respective baseline values and placebo. Gastro-intestinal disturbances were recorded in 67% of patients during therapy with acarbose.

CONCLUSION

Acarbose has a positive therapeutic effect on glucose tolerance in cystic fibrosis patients, as shown by attenuation of postprandial plasma glucose increase and a significant decrease in insulin secretion response. However, acarbose treatment was associated with adverse gastro-intestinal effects that may prevent patients from accepting long-term therapy.

European study on dose-response relationship of acarbose as a first-line drug in non-insulin-dependent diabetes mellitus: efficacy and safety of low and high doses

The aim of this double-blind, placebo-controlled, multinational, five-arm study was to investigate the dose-response relationship of acarbose as a first-line drug in the treatment of type 2 diabetes (non-insulin dependent) over a range of minimal and maximal doses according to the European recommendations. The study included 495 patients from 7 countries who were insufficiently controlled with diet alone (glycosylated haemoglobin HbA1C 6.5%-9%). Acarbose, 25, 50, 100 or 200 mg t.i.d., or placebo t.i.d. was given for 24 weeks. Even a low dosage of 25 mg t.i.d. acarbose reduced fasting and postprandial blood glucose levels (1 h postprandial -11.6%; 2 h postprandial -11.3%). Acarbose in a dosage of 200 mg t.i.d. had the greatest effect on these parameters. In the placebo group the mean 2 h postprandial area under the curve (AUC) value for blood glucose was 22.6 mmol/l after 24 weeks' therapy. The mean 2 h postprandial AUC values in the patients given acarbose at doses of 25, 50, 100 and 200 mg t.i.d. were found to be 21.2, 19.6, 20.3 and 18.5 mmol/l, respectively. The corresponding HbA1C values for the placebo and acarbose groups were 7.83%, 7.37%, 7.08%, 6.98% and 6.79%. Interestingly, there was a plateau of blood glucose level at a dosage of 50-100 mg t.i.d. The frequency of flatulence decreased with the duration of drug therapy, but we could not find a linear relationship between doses of acarbose and the gastrointestinal side effects. Less than 3% of patients stopped tablet intake due to adverse events.

Efficacy of 24-week monotherapy with acarbose, metformin, or placebo in dietary-treated NIDDM patients: the Essen-II Study

PURPOSE

To compare the therapeutic potential of acarbose, metformin, or placebo as first line treatment in patients with non-insulin-dependent diabetes mellitus (NIDDM).

PATIENTS AND METHODS

Ninety-six patients with NIDDM (35-70 years of age, body mass index (BMI) < or = 35 kg/m2, insufficiently treated with diet alone, glycated hemoglobin (HbA1c; 7% to 11%) were randomized into 3 groups and treated for 24 weeks with acarbose, 3 x 100 mg/day, or metformin, 2 x 850 mg/day, or placebo. Efficacy, based on HbA1c (primary efficacy criterion), fasting blood glucose (BG) and insulin, 1 hour postprandial BG and insulin (after standard meal test), postprandial insulin increase, plasma lipid profile, and tolerability, based on subjective symptoms and laboratory values were determined every 6 weeks. Analysis of covariance was performed for endvalues with adjustment on baseline values. Ninety-four patients were valid for efficacy evaluation.

RESULTS

Both active drugs showed the same improvement of efficacy criteria compared with placebo. Baseline adjusted means at endpoint were as follows: BG, fasting and 1 hour postprandial, 9.2 mM and 10.9 mM with placebo, 7.6 mM and 8.7 mM with acarbose, and 7.8 mM and 9.0 mM with metformin; HbA1c was 9.8% with placebo, 8.5% with acarbose, and 8.7% with metformin. Comparisons: acarbose versus placebo and metformin versus placebo were statistically significant, but not acarbose versus metformin. No effect on fasting insulin could be observed. Relative postprandial insulin increase was 1.90 with placebo, 1.09 with acarbose, and 1.03 with metformin. Comparisons: acarbose versus placebo and metformin versus placebo were statistically significant, but not acarbose versus metformin. With respect to lipid profile, acarbose was superior to metformin. Low-density lipoprotein (LDL)/high-density lipoprotein (HDL) cholesterol ratio increased by 14.4% with placebo, was unchanged with metformin, but decreased by 26.7% with acarbose. Comparisons: acarbose versus placebo and acarbose versus metformin were statistically significant, but not metformin versus placebo. Slight body weight changes were observed with acarbose (-0.8 kg) and metformin (-0.5 kg), but not with placebo. Acarbose led to mild or moderate intestinal symptoms in 50% of the patients within the first 4 weeks, but in only 13.8% of the patients within the last 4 weeks.

CONCLUSIONS

Acarbose and metformin are effective drugs for the first line monotherapy of patients with NIDDM. With respect to plasma lipid profile, especially HDL cholesterol, LDL cholesterol and LDL/HDL cholesterol ratio acarbose may be superior to metformin.

Effect of acarbose and simultaneous antacid therapy on blood glucose

In a single-centre, placebo-controlled, clinical study, the influence of an antacid containing magnesium hydroxide and aluminium hydroxide (Maalox 70; 10 ml) on the pharmacodynamics of the oral antidiabetic drug acarbose (Glucobay 100, Bay g 5421, CAS 56180; 100 mg) was tested in 24 healthy male volunteers. The drugs were given alone or in combination and were compared with placebo. Volunteers were randomized into four different treatment groups. The daily medication over 4 days was 1 x 1 placebo tablet, or 1 x 1 tablet containing 100 mg acarbose, or 1 x 1 tablet containing 100 mg acarbose plus 10 ml antacid suspension, or 1 x 1 placebo tablet plus 10 ml antacid suspension, interrupted by wash-out phases of 6-10 days between successive treatments. Efficacy was assessed on the basis of postprandial blood glucose and serum insulin levels after administration of 75 g sucrose, and was measured as maximal concentrations and 'area under the curve' (0-4 h). No influence of the antacid on the blood glucose and insulin-lowering effect of acarbose could be detected. Hence, there does not appear to be a significant interaction between acarbose and the antacid tested. Antacids similar to that tested do not need to be classified as a contraindication when used in combination with acarbose.

The use of acarbose in the primary-care setting: evaluation of efficacy and tolerability of acarbose by postmarketing surveillance study

The efficacy and tolerability of acarbose were examined in a postmarketing surveillance study of 10,462 patients (829 insulin-dependent diabetes mellitus (IDDM), 9,440 non-insulin-dependent diabetes mellitus (NIDDM), 193 not classified) during a 12-week treatment period. The median duration of diabetes was 60 months for men and 72 months for women in IDDM patients, and 40 months for men and 60 months for women in NIDDM patients. Of the Type II patients, 28.9% were treated with diet only; 58.1% additionally with sulfonylureas; 8.6% with insulin; and 4.3% with both sulfonylureas and insulin. The additional acarbose therapy led to a reduction of the mean fasting blood glucose levels (51 mg/dL for IDDM; 52 mg/dL for NIDDM) and 1 h postprandially (55 mg/dL for IDDM; 63 mg/dL for NIDDM). The HbA1 levels were reduced by 1.5%. Tolerability was good: 78.6% of patients had no adverse events; 19% reported meteorism/flatulence; 3.2%, diarrhea. Hypoglycemia was found in 0.8% of Type I and 0.6% of Type II patients who received concurrent insulin (n = 8) or glibenclamide (n = 1) treatment. Laboratory investigations gave no indication of other adverse effects, e.g. elevated levels of transaminases or creatinine. This postmarketing surveillance study documents the therapeutic benefit and the good tolerability of acarbose.

Efficacy of 24-week monotherapy with acarbose, glibenclamide, or placebo in NIDDM patients. The Essen Study

OBJECTIVE

To compare the different therapeutic principles of alpha-glucosidase inhibitors and sulphonylureas as first-line treatment in non-insulin-dependent diabetes mellitus (NIDDM) patients with dietary failure.

RESEARCH DESIGN AND METHODS

Ninety-six NIDDM patients (35-70 years of age, body mass index [BMI] < or = 35), insufficiently treated with diet alone (HbA1c 7-9%) were randomized into three groups and treated for 24 weeks with acarbose, glibenclamide, or placebo. Efficacy, based on fasting blood glucose (BG), BG 1 h after ingestion of standard breakfast (postprandial), serum insulin, postprandial insulin increase, and HbA1c; and tolerability, based on subjective symptoms and laboratory values, were investigated every 6 weeks. Efficacy evaluation was valid for 85 patients.

RESULTS

The test drugs were dosed as follows: 100 mg acarbose (A) three times a day, 1 placebo tablet three times a day, 3.5 mg glibenclamide tablets dosed 1-0-0 or 1-0-1, mean dose 4.3 mg/day. Compared with the placebo, both drugs showed the same mean efficacy on fasting BG (-1.4 mM with acarbose, -1.6 mM with glibenclamide), 1-h postprandial BG (-2.2 mM with acarbose, -1.9 mM with glibenclamide), and HbA1c (-1.1% with acarbose, -0.9% with glibenclamide); but they showed a marked difference in 1-h postprandial insulin values (-80.7 pM with acarbose, 96.7 pM with glibenclamide). The mean relative insulin increase (1-h postprandial) was 1.5 in the placebo group, 1.1 in the acarbose group, and 2.5 in the glibenclamide group. No changes in body weight could be observed. No adverse events were seen under placebo. Acarbose led to mild or moderate intestinal symptoms in 38% of patients. Glibenclamide led to hypoglycemia, which could be solved by dose reduction, in 6% of patients. No dropouts occurred in any of the treatment groups.

CONCLUSIONS

Acarbose and glibenclamide are effective drugs for the monotherapy of NIDDM patients when diet alone fails. Because postprandial insulin increase has been shown to be associated with increased risk for cardiovascular disease, acarbose, which lowers pp increase, may be superior to glibenclamide, which elevates postprandial insulin increase.

Therapeutic potentials of acarbose as first-line drug in NIDDM insufficiently treated with diet alone

OBJECTIVE

Acarbose inhibits alpha-glucosidases of the small intestine and thus delays glucose release from complex carbohydrates. Therefore, its efficacy and acceptability as a first-line drug in non-insulin-dependent diabetes mellitus (NIDDM) insufficiently treated with diet alone was tested in a randomized double-blind placebo-controlled study.

RESEARCH DESIGN AND METHODS

Ninety-four NIDDM subjects, aged 43-70 yr with average body mass index of 28 kg/m2 and undergoing a pretreatment period of at least 3 mo with diet alone, were treated with 100 mg acarbose three times daily or placebo for 24 wk. The patients were recruited after a 4-wk screening period of dietary reinforcement. The inclusion limits for patients termed diet not satisfactory were fasting blood glucose (FBG) greater than or equal to 7.8 mM and/or postprandial blood glucose (BG) greater than or equal to 10 mM.

RESULTS

FBG was lowered in the acarbose group from 9.8 to 8.4 mM and in the placebo group from 10.2 to 9.6 mM after 24 wk (P = 0.007 vs. placebo). The most impressive therapeutic effect was a highly significant reduction of postprandial hyperglycemia for at least 5 h after the test meal (1-h postprandial BG with acarbose 10.4 mM and placebo 13.5 mM at 24 wk, P less than 0.001) accompanied by a significant decrease in HbA1 (acarbose 8.65%, placebo 9.32%, P = 0.003). Whereas C-peptide and fasting serum insulin were not significantly affected by acarbose, postprandial insulin increment was approximately 30% lower after 24 wk compared with placebo. Furthermore, acarbose significantly reduced 1-h postprandial triglyceride levels. After an initial phase of greater than 4 wk (when 76.6% in the acarbose group vs. 28% on placebo complained about flatulence, P less than 0.001), the drug was well accepted. At the end of the study, only 32% showed mild or moderate gastrointestinal sensations.

CONCLUSIONS

Extrapolation shows that acarbose is an efficient and acceptable drug for the treatment of NIDDM with poor metabolic control by diet alone. It has beneficial effects on postprandial hyperinsulinemia and postprandial hypertriglyceridemia.

Beneficial effects on serum lipids in noninsulin dependent diabetics by acarbose treatment

Acarbose (Bay g 5421, Glucobay; CAS 56180-94-0) inhibits alpha-glucosidases of the small intestine and thus delays glucose release from complex carbohydrates. It is therefore efficient as a first-line drug in the treatment of noninsulin-dependent diabetics (NIDDM) insufficiently treated with diet alone. Information is scarce whether under acarbose treatment the lipid metabolism can also be improved. Therefore the changes of triglycerides, cholesterol and HDL-cholesterol were analyzed in a randomized double-blind placebo-controlled trial. In brief, 94 NIDDM aged 43 to 70, after a pretreatment period of at least 3 months, were treated with 100 mg acarbose t.i.d. or placebo for 24 weeks. The patients were recruited after a 4-week screening phase with reinforcement of diet. The most impressive results of acarbose treatment were lowering of blood glucose and insulin, especially in the postprandial state, and of HbA1 (glycosylated hemoglobin). Results on lipids: The initial serum cholesterol levels showed a broad spectrum. Low concentrations remained unchanged under acarbose, while high concentrations (the upper tercile) decreased from 273 to 251 mg/dl. This effect was statistically significant compared to placebo. HDL-cholesterol levels increased continuously under acarbose and placebo as well thus indicating some study effect. Similarly, fasting triglycerides leveled down under acarbose and placebo. However, drastic differences appeared in postprandial triglycerides which were checked 1 and 5 h after a test meal given at entry and at finish of the study. The lowering by acarbose compared to placebo was highly significant for the 1 h postprandial concentrations. It is concluded that acarbose treatment can reduce elevated cholesterol concentrations and postprandial triglyceride concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of starch malabsorption on colonic function and metabolism in humans

To study the impact of starch on colonic function and metabolism, 12 healthy volunteers consumed a controlled diet rich in starch for two 4-wk periods. In one of the study periods they received the glucosidase inhibitor acarbose (BAY g 5421) and placebo in the other. Stool wet weight increased by 68%, stool dry weight by 57%, fecal water content by 73%, and the mean transit time by 30% on acarbose. Breath hydrogen was significantly higher on acarbose, indicating stimulated carbohydrate fermentation in the colon. Fecal bacterial mass (+78%), total stool nitrogen (+53%), bacterial nitrogen (+200%), and stool fat (+56%) were higher in the acarbose than in the control period. The stimulation of fermentation in the human large intestine may be important in colonic and possibly other diseases.

In situ hybridization analysis of macrophage-derived tumor necrosis factor and interleukin-1 mRNA

Tumor necrosis factor (TNF) and interleukin-1 (IL-1) play an intimate role in the initiation and maintenance of inflammatory reactions due to their pluripotent activities. In this paper, we describe the use of an in situ hybridization analysis as an effective means to probe for TNF and IL-1 mRNA levels in primary macrophage cultures and macrophage cell lines. A significant increase in lipopolysaccharide (LPS)-induced TNF mRNA accumulation was demonstrated by in situ hybridization using either a 35S-labeled synthetic oligonucleotide (30-mer) complementary to TNF mRNA or a 35S-randomly primed labeled TNF DNA probe. An augmentation in TNF mRNA accumulation, as assessed by increasing grains/cell, was demonstrated over a wide concentration range of LPS. This accumulation was shown using both immunologically elicited primary macrophage cultures and the macrophage cell line RAW 264.7. Interestingly, the RAW 264.7 constitutively produced TNF in the absence of specific stimulus and this tonic production was observed at the molecular level via in situ hybridization analysis. Specificity of the in situ hybridization technique was shown by a complete loss in binding of 35S-probe after either RNase digestion or competition with "cold-labeled" probe. beta-actin served as a 35S-labeled control probe where the number of actin-specific grains/cell was not altered by stimulating macrophages with LPS. IL-1 alpha mRNA was also increased by LPS stimulation of macrophages as assessed by in situ hybridization. The LPS-dependent increase in macrophage mRNA for TNF and IL-1 alpha, as assessed by in situ hybridization, was confirmed by classical Northern blot analysis as well as the production of biologically-active protein.

Prostaglandin E2 regulates macrophage-derived tumor necrosis factor gene expression

Tumor necrosis factor-alpha (TNF) is a macrophage-derived peptide that is known to be an important mediator in various physiologic and immunologic events. Although the effector function of TNF has received recent attention, there is relatively little information regarding factors that regulate TNF expression. Highly Ia-positive murine peritoneal macrophages obtained via complete Freund's adjuvant elicitation were challenged with lipopolysaccharide (LPS) and assessed for the production and regulation of TNF at the cellular and molecular levels. In response to 1 microgram/ml LPS, the kinetics of functionally active TNF reached a maximum at approximately 3-4 h. The plateau in TNF levels was concomitant with an accelerated increase in prostaglandin E2 production. The addition of exogenous PGE2 demonstrated a dose-dependent reduction in LPS-induced TNF activity at the cellular level, as well as a significant reduction in TNF mRNA accumulation as assessed by Northern blot and in situ hybridization analysis. The reduction in LPS-stimulated mRNA accumulation by PGE2 was shown to occur at least at the level of transcription, since nuclear run-off analysis showed a specific reduction in TNF transcripts. These studies demonstrate that PGE2 can regulate macrophage-derived TNF gene expression.

Tumor necrosis factor production by human sarcoid alveolar macrophages

Tumor necrosis factor (TNF) is an oncolytic peptide that may also exert many other biologic effects. Experimentally, immunologically activated mononuclear phagocytes stimulated with endotoxin (LPS) produce TNF, while resting mononuclear phagocytes stimulated with LPS produce little TNF. To date, the ability of human alveolar macrophages (AMs) to produce TNF has not been clearly delineated. As pulmonary sarcoidosis is a granulomatous inflammatory disorder characterized by immunologically activated AMs, we investigated the production of TNF by AMs obtained by bronchoalveolar lavage from 7 normal volunteers and 13 patients with pulmonary sarcoidosis. The AMs were cultured with and without LPS, and TNF production was assessed by an in vitro cytotoxicity assay. Unstimulated sarcoid and normal AMs produced little TNF, but LPS stimulation enhanced TNF production by both normal and sarcoid AMs. Furthermore, LPS-stimulated sarcoid AMs produced more TNF than normal AMs (84.9 +/- 16.7 versus 32.5 +/- 10.2 units/million cells, P less than 0.05). It is concluded that human AMs can produce TNF and that sarcoid AMs are primed and can produce significantly more TNF, compared with normal AMs.

Dynamics of arachidonic acid metabolism in macrophages from delayed-type hypersensitivity (Schistosoma mansoni egg) and foreign-body-type granulomas

The present study examines the kinetics of arachidonic acid (AA) metabolism by murine macrophages isolated from sites of experimentally induced pulmonary granulomatous inflammation. Macrophages of T-cell-mediated hypersensitivity lesions induced by Schistosoma mansoni eggs (SE-GM) and non-T-cell-mediated foreign-body-type lesions (FB-GM) induced by Sephadex beads were examined. Overall, macrophages from both types of lesions produced mainly lipoxygenase pathway metabolites, leukotrienes, and monohydroxyeicosatetraenoic acids (mono-HETEs). Early after induction (4 days [4D]), SE-GM showed an augmented zymosan-stimulated AA release and metabolism compared to resident peritoneal macrophages. Macrophages from mature lesions (8-32D) showed constitutive synthesis of metabolites and were refractory to zymosan stimulation. Both SE-GM and FB-GM showed augmented AA uptake incorporating a large proportion into neutral lipids. A direct comparison of SE-GM and FB-GM revealed that the T-cell-mediated lesion produced lesser amounts of prostaglandins and leukotrienes and showed reduced incorporation of AA into phosphatidylcholine. These data suggest that AA metabolism by granuloma macrophages is sequentially modified during recruitment and activation at sites of chronic inflammation.

Comparison of the biological and immunological activities of serum luteinizing hormone and follicle stimulating hormone in infertile males

The biological and immunological activities of luteinizing hormone (LH) and follicle stimulating hormone (FSH) in the serum of infertile males were determined by radioreceptor (RRA) and radioimmunoassay (RIA), respectively. In some sera the biological activity of serum LH was lower than expected on the basis of the RIA-data. In contrast, some sera contained unusually high levels of biologically active LH as demonstrated by RRA, despite not being detected in these amounts by RIA. Prolonged exposure of the gonad to such high levels of biologically active LH might cause end-organ desensitization resulting in infertility. The detection of such cases by the use of RRA could permit therapy in these individuals or exclude patients from treatment.

Effect of a sorbitol-rich diet on plasma and erythrocyte sorbitol concentrations in normal and diabetic subjects

Four normal subjects and seven diabetic patients ingested for 5-7 days a sorbitol-rich diet (44g of sorbitol/day). No obvious change in either plasma or erythrocyte sorbitol concentrations was observed. Thus, the regulation of endogenous sorbitol production appears unaffected by the sorbitol content of the diet.

Comparative study of isomalt and sucrose by means of continuous indirect calorimetry

Isomalt (Palatinit) an equimolar mixture of alpha-D-glucopyranosido-1,6-sorbitol and alpha-D-glucopyranosido-1,6-mannitol, was compared to sucrose in a prospective double-blind controlled crossover study. The acute effects of oral ingestion of 30-g loads of isomalt or sucrose on plasma glucose, insulin, free fatty acids (FFA), lactic acid, and carbohydrate (CHO) and lipid oxidation were studied over six hours by means of continuous indirect calorimetry in ten healthy normal-weight subjects. Unlike sucrose, whose ingestion was followed by significant changes in plasma glucose, insulin, and lactic acid during the first 60 minutes of the test, no significant changes in these parameters were observed following the administration of isomalt. The increase in CHO oxidation occurring between 30 and 150 minutes was significantly lower (P less than 0.01) following isomalt than after sucrose. Conversely, the decrease in lipid oxidation was significantly less (P less than 0.01) after isomalt in comparison to sucrose. It is concluded that the rise in CHO oxidation and in plasma glucose and insulin levels is markedly reduced when sucrose is replaced by an equal weight of isomalt. In contrast to other sugar substitutes, no increase in plasma lactic acid was observed after isomalt administration.

[Palatinite in type II diabetics. Effect on blood-glucose, serum-insulin, C-peptide and free fatty acids]

In a randomized cross-over study, 24 type II diabetics were given at first 50 g palatinite and later 50 g glucose or vice versa in the morning before food intake. After administration of glucose there was a definite rise in blood-glucose, serum-insulin and C-peptide concentrations. After palatinite the rise of blood-glucose as well as serum-insulin and C-peptide was significantly less. Subjective side-effects were noted only after a single high dose of palatinite. Nonetheless, palatinite appears to be suitable as a sugar substitute in a diabetic diet, since in comparison with glucose there are no significant changes in blood-sugar levels and no additional insulin consumption is induced. Furthermore, because of its low energetic utilization it has an advantage over other sugar substitutes.

Practical bacteriologic monitoring of the burn victim

A comprehensive picture of the burn wound microflora is now possible as a result of recent technologic advances. The microflora of the burn wound can be characterized with respect to its number, type, location, and antibiotic sensitivity. These parameters can be measured in sufficient time to influence the decision of the burn surgeon. The microflora of the surface of the burn wound and the burn wound itself are examined separately by different sampling techniques. For the surface microflora, the gauze capillary techniques employed, while incisional biopsies are used to monitor the organisms in the burn wound. After sampling, suspensions of the specimens are created which in turn are subjected to direct microscopic measurement, quantitative culture procedures, and immediate antibiotic sensitivity testing. Histologic examination of the burn wound is performed concomitantly with this bacteriologic examination to determine the depth of bacterial invasion as well as to detect the presence of either mycotic or herpetic infections.