A bioequivalence study of Levothyroxine tablets versus an oral Levothyroxine solution in healthy volunteers

Probably for genetic reasons a substantial part of the Greek population requires Levothyroxine treatment. Since commercially available Levothyroxine was first marketed, the manufacture and storage of the drug in tablet form has been complicated and difficult; and as cases of therapeutic failure have frequently been reported following treatment with this medicinal agent, quality control is an essential factor. Due to the unreliability of Levothyroxine-based commercial products, in the present study we decided to follow the Food and Drug Administration (FDA) guidelines*, and use a Levothyroxine solution as reference product. The bioavailability of the Levothyroxine sodium tablet formulation THYROHORMONE/Ni-The Ltd (0.2 mg/tab) and that of a reference oral solution (0.3 mg/100 ml) under fasting conditions were compared in an open, randomized, single-dose two-way crossover study. Twenty four healthy Caucasian volunteers (M/F=15/9, mean age=32.9+/-7.4yr) participated in the study. Bioavailability was assessed by pharmacokinetic parameters such as the area under plasma concentration-time curve from time zero up to the measurable last time point (AUC(last)) and the maximum plasma concentration (Cmax). Heparinized venous blood samples were collected pre-dose and up to a 48-hour period post-dose. Levothyroxine sodium in plasma samples was assayed by a validated electrochemiluninescent immunoassay technique. Statistical analysis showed that the post-dose thyrotropin-stimulating hormone (TSH) levels decreased significantly (p<0.05). Regarding Levothyroxine (T4), the point estimate of the test formulation to the reference formulation ratios (T/R) for AUC(last) and Cmax was 0.92 with 90% confidence limits (0.90, 0.94) and 0.93 with 90% confidence limits (0.91, 0.94), respectively. Regarding triiodo-L-thyronine (T3), the point estimate for the T/R ratios of AUC(last) and Cmax was 0.92 with 90% confidence limits (0.90, 0.95) and 0.94 with 90% confidence limits (0.92, 0.95), respectively. The 90% confidence limits for the pharmacokinetic parameters AUC(last) and Cmax lie within the acceptance limits for bioequivalence (0.80, 1.25), for both T3 and T4.

Labeling of monoclonal antibodies with 153Sm for potential use in radioimmunotherapy

The labeling of a monoclonal (anti-CEA) and a polyclonal (IgG) antibody with 153Sm has been investigated, using the bicyclic anhydride of DTPA (cDTPAa) as the chelating agent. The radiochemical study was performed using a combination of radioanalytical techniques (gel filtration, HPLC, ITLC-SG and SDS-PAGE). Optimization of factors affecting labeling (pH, Ab, Ab-DTPA concentration, etc.) leads to a labeling yield higher than 90%. Biodistribution studies in normal mice showed slow blood clearance and high uptake into the liver, kidney and lungs.

Idiopathic fibrosing pancreatitis and Crohn's disease: an interesting association

Idiopathic fibrosing pancreatitis is an uncommon condition in children and adolescents of unknown aetiology. This syndrome has been reported in 36 cases so far. To our knowledge none of these cases was definitively associated with Crohn's disease. In this report we describe a young female patient who developed Crohn's disease of the colon 5 years after having been diagnosed with idiopathic fibrosing pancreatitis. The differential diagnosis between this syndrome associated with Crohn's disease and pancreatic Crohn's disease or fibrosing colonopathy, an entity related to pancreatic enzyme therapy, is discussed.

Radioimmunoscintigraphy and radioimmunotherapy in cancer: principles and application

Radioimmunoscintigraphy (RIS) and radioimmunotherapy (RIT) are recent approaches in the diagnosis and treatment of cancer. They take advantage of the antibody specificity of tumor surface antigens and of the emitted radiation from suitable radioisotopes, as a means of imaging (RIS) or therapy (RIT). Research into RIS and RIT radiolabelled agents remains an ongoing process. Principles governing the choice of radionuclides, labelling protocols, antibody suitability, and optimization of "tumor to normal tissue ratios" are the same for both RIS and RIT. The investigational stages of the labelled product, prior to clinical application, are also the same. These stages include radiochemical and radiobiological evaluation as well as determination of immunoreactivity. Furthermore, RIS may be considered as the first stage in development, before progressing on to RIT. Differences between RIS and RIT are associated with the application of each technique, that is, the type of radiation emitted by the isotope, dosage regimens, haematopoetic toxicity and the appearance of human antimurine antibody response (HAMA). RIS has found widespread clinical application, detecting a variety of tumors. However, its potential lies in patient management and in detecting metastases. On the other hand RIT is still in its infancy. It appears promising, and for the moment is used as a complementary technique to surgery and/or chemotherapy in clinical trials on cancer treatment. Finally, incorporation of these basic principles arising from past experiences, into the design of RIT trials improve responses.

Oral administration of recombinant human granulocyte macrophage colony-stimulating factor in the management of radiotherapy-induced esophagitis

Radiation-induced esophagitis often results in treatment interruption, which may severely affect the probability of control of the local disease in patients undergoing chest radiotherapy (RT). No effective regimen that would reduce the incidence and severity of this complication has been identified up to now. Although acceleration of oral mucosal healing using topical recombinant human granulocyte macrophage colony-stimulating factor (rhGM-CSF) has been reported, the mechanism of such an interaction remains obscure. Effective topical application of rhGM-CSF for the treatment of radiation-induced esophagitis has never been reported in the past. In pharmacological studies, we observed that glycerol exerts a remarkable stabilizing effect on rhGM-CSF immunoreactivity. After studying the kinetics of esophageal emptying with nuclear imaging, we proposed a rhGM-CSF regimen that could be applied for topical treatment of esophagitis during RT. The regimen was applied for 5 consecutive days in a cohort of 36 patients undergoing chest RT, immediately after the documentation of grade 3 esophagitis. RT was not interrupted. Mucosal biopsies were performed endoscopically and examined immunohistochemically. Regression of dysphagia to grade 0/1 was observed in 19 of 36 (52%) patients, whereas grade 2 dysphagia persisted in 12 of 36 (33%) patients. Progression of dysphagia was seen in 5 of 36 (14%) patients. Recurrence of severe esophagitis within 5-8 days after rhGM-CSF therapy was observed in 7 of 31 (22%) patients with initial response to rhGM-CSF. Four of these patients presented significant improvement of symptomatology after additional rhGM-CSF medication. In immunohistochemical studies, active intraepithelial neovascularization and thymidine phosphorylase and vascular endothelial growth factor overexpression were observed in the damaged epithelium, which was not accompanied by macrophage or neutrophil infiltration. We conclude that rhGM-CSF topical therapy (p.o. administration) exerts a significant therapeutic effect against RT-induced esophagitis. The rhGM-CSF mucosa healing effect is probably due to its direct angiogenic activity and/or to the potentiation of the activity of other angiogenic factors released by the damaged epithelium.

Carcinoma of the ampulla of Vater in Crete. A clinical and ERCP registry over eight years

BACKGROUND

Carcinoma of the ampulla of Vater is an infrequent tumor that can be diagnosed, early.

PATIENTS AND METHODS

Twenty-four patients with histologically proven carcinoma of the ampulla of Vater were retrospectively studied and their data were analyzed.

RESULTS

Most common presenting symptoms were jaundice (67%), weight loss (58%), fever and pain (54%). Endoscopic biopsies which were taken in 19 patients revealed carcinoma or dysplasia in 15 patients and were normal for in the rest. Twelve patients were treated with a Whipple's resection, 5 with local resection, 2 with palliative surgery and 2 received a stent endoscopically. During a mean follow-up period of 25 months, (range 1-82) 12 deaths were noted, and one patient was lost during follow-up.

CONCLUSIONS

Presenting symptoms, endoscopic and histological findings were similar as in other series. The contribution of duodenoscopy, ERCP and endoscopic biopsy is essential for diagnosis but endoscopic biopsies may be misleading.

Autoimmune hemolytic anemia and positive Coombs test associated with ulcerative colitis

OBJECTIVES

To estimate the frequency of autoimmune hemolytic anemia and Coombs positivity without overt hemolysis in ulcerative colitis, to determine possible subsets of patients with ulcerative colitis susceptible to this complication, and to assess the efficacy of the applied therapeutic modalities.

METHODS

Three hundred and two patients with ulcerative colitis treated at the University Hospital of Heraklion, Crete, over a 6-yr period were included. Within this group, a subgroup of 152 patients were studied prospectively for the presence of a positive direct Coombs test.

RESULTS

Autoimmune hemolytic anemia was diagnosed in five of 302 patients with ulcerative colitis (1.7%). One more patient developed Coombs-positive hemolytic anemia, attributed to sulfasalazine. A positive Coombs test without evidence of hemolysis was found in three of 152 patients (2%). The mean age of all Coombs-positive patients was 50.5 yr, and there was a definitive male preponderance (male: female, 2:1). Autoimmune hemolytic anemia occurred during active colitis in all cases. The mean time between the onset of colitis and the diagnosis of autoimmune hemolytic anemia was 17 months. Three of five patients with autoimmune hemolytic anemia (60%) and seven of nine of all Coombs-positive patients (77.7%) had total colitis. All patients with autoimmune hemolytic anemia were treated initially with large doses of corticosteroids. Three of five (60%) had good hematological responses. One patient responded to the addition of azathioprine, and one underwent splenectomy and proctocolectomy.

CONCLUSIONS

In this study, the frequency with which autoimmune hemolytic anemia was associated with ulcerative colitis was higher than in previous reports. The complication occurred early in the course of colitis and was related to activity and extent of the disease. In contrast to others studies, we found a preponderance of males. Although corticosteroids and/or immunosuppressive therapy was successful in most of our cases, one patient required surgery.

A prospective epidemiologic study of Crohn's disease in Heraklion, Crete. Incidence over a 5-year period

BACKGROUND

There has been an impression from published work that Crohn's disease is less common in southern than in northern Europe. A low incidence of Crohn's disease has been observed in Greece, but conclusive data are still lacking.

METHOD

A 5-year prospective and population-based epidemiologic study of Crohn's disease was carried out in a well-defined area of Crete.

RESULTS

The mean annual incidence of the disease for the years 1990-94 was 3.0 per 10(5) inhabitants. During the study period the incidence increased from 1.9/10(5) in 1990 to 3.8/10(5) in 1994. The male to female ratio was 2.4:1. The age group 25-34 years had the highest age-adjusted incidence (6.3/10(5)). The incidence of Crohn's disease was also found to be higher in smokers, in urban areas, and in people with high educational level.

CONCLUSION

Crohn's disease is common in Heraklion, Crete. The findings of the study are discussed in relation to those of other European countries.

Lysis of erythrocytes by Trichomonas vaginalis

The in vitro hemolytic activity of 4 isolates of Trichomonas vaginalis was investigated. Repetitive hemolysis assays of any one isolate showed cyclical fluctuations in hemolytic activity, varying over 24 hr of continuous culture. Maximal hemolytic activity was detected using trichomonads in the lag phase of the growth cycle. Investigations showed that hemolysis was a contact-dependent phenomenon and microscopic investigation of samples showed a significant correlation between hemolysis and attachment of erythrocytes to the trichomonad surface. Quantitative data from cytoadherence assays using [51Cr]-labeled erythrocytes were consistent with these observations. It is suggested that hemolytic activity is dependent upon adherence of red blood cells to the surface of T. vaginalis.

Antigenic role of single residues within the main immunogenic region of the nicotinic acetylcholine receptor

The target of most of the autoantibodies against the acetylcholine receptor (AChR) in myasthenic sera is the main immunogenic region (MIR) on the extracellular side of the AChR alpha-subunit. Binding of anti-MIR monoclonal antibodies (mAbs) has been recently localized between residues alpha 67 and alpha 76 of Torpedo californica electric organ (WNPADYGGIK) and human muscle (WNPDDYGGVK) AChR. In order to evaluate the contribution of each residue to the antigenicity of the MIR, we synthesized peptides corresponding to residues alpha 67-76 from Torpedo and human AChRs, together with 13 peptide analogues. Nine of these analogues had one residue of the Torpedo decapeptide replaced by L-alanine, three had a structure which was intermediate between those of the Torpedo and human alpha 67-76 decapeptides, and one had D-alanine in position 73. Binding studies employing six anti-MIR mAbs and all 15 peptides revealed that some residues (Asn68 and Asp71) are indispensable for binding by all mAbs tested, whereas others are important only for binding by some mAbs. Antibody binding was mainly restricted to residues alpha 68-74, the most critical sequence being alpha 68-71. Fish electric organ and human MIR form two distinct groups of strongly overlapping epitopes. Some peptide analogues enhanced mAb binding compared with Torpedo and human peptides, suggesting that the construction of a very antigenic MIR is feasible.