Localization of epidermal growth factor receptors in the human prostate by biochemical and immunocytochemical methods.

The receptor for epidermal growth factor (EGF) was characterized in the particulate fraction from human benign prostatic hyperplasia (BPH) and was present in 85% of tissues analysed. The uptake of 125I-labelled EGF by BPH was dependent on both time and temperature, with maximum specific uptake achieved after incubation for 90 min at 37 degrees C. Binding characteristics revealed two classes of binding sites of higher (mean dissociation constant (Kd) +/- S.D. = 0.8 +/- 0.2 nmol/l) and lower (Kd = 7.6 +/- 2.8 nmol/l) affinities. Competition studies demonstrated the specificity of the receptor assay since the binding of labelled EGF was abolished with excess unlabelled EGF but not with excess unlabelled human GH, human insulin, venom nerve growth factor, human FSH, human LH and human prolactin. There was a complex biphasic relationship between specific binding and protein concentration in the range 0.1-8 mg/ml. Subcellular fractionation of BPH homogenates demonstrated that the bulk of the specific binding was confined to the 800 g (crude heavy pellet) and 15,000 g (mitochondrial pellet) fractions. The 105,000 g (microsomal pellet) and the 105,000 g (cytosol fraction) exhibited low and variable binding capacities for the growth factor. The presence of EGF receptor was also confirmed by immunocytochemical staining of frozen sections from BPH using monoclonal antibody specific for EGF receptors. A positive correlation between 125I-labelled EGF binding and the intensity of staining was found. The presence of a specific EGF-binding receptor protein in human BPH tissues suggests that EGF may play a role in the pathogenesis of human BPH.

Faecal pancreatic elastase--1 a non invasive measure of exocrine pancreatic function.

BACKGROUND: Faecal pancreatic elastase-1 is a laboratory based test used for the diagnosis or exclusion of exocrine pancreatic insufficiencies. Pancreatic elastase-1, is released into blood circulation during inflammation of the pancreas, but unlike most pancreatic enzymes it is stable during intestinal passage and not degraded. OBJECTIVES: The major objective of this work was to establish the assay of faecal pancreatic elastase-1 in spot stool samples as an exocrine pancreatic function test at Korle-Bu (a referral) hospital in Ghana, for the diagnosis of pancreatic diseases. METHOD: Twenty-five apparently healthy persons; mean age of 43.4 years and thirty-two patients with various pancreatic diseases, mean age 51.4 years were referred for the test based on clinical presentation, imaging studies and biopsy findings. The male to female ratio was 6.4:3.6 and 8.1:1.9 respectively. An ELISA technique which recognizes human pancreatic elastase-1 from spot stool samples was employed for the test and read photometrically at 405nm. RESULTS: Elastase-1 activity in spot stool samples from apparently healthy group ranged from 165 to 870mg/g with a mean of 379 (SE 41)mg/g, and a range of 20 to 285mg/g with a mean of 112.9 (SE 11.6)mg/g obtained for the pancreatic disease group. Disease severity was classified as mild to moderate with elastase-1 concentration between 100 and 200mg/g stool and the severe pancreatic insufficiency group with elastase-1 concentration of less than 100mg/g stool. The pancreatic elastase-1 was found to be stable in faeces for several weeks when stored frozen, hence the convenience for batch determinations. CONCLUSION: The test is non invasive and can assist with the diagnosis of inflammatory conditions of the pancreas where imaging results are equivocal.

Total antioxidant status in non-insulin-dependent diabetes mellitus patients in Ghana.

Total antioxidant status (TAS) was measured in thirty-five (35) non-insulin-dependent diabetes mellitus (NIDDM) patients aged 40 to 65 (mean +/- SE 49.6 +/- 1.0) years. Patients were on diet and oral hypoglycaemic drug (Daonil) therapy with fasting plasma glucose (FPG) >7.8mmol/l. Similar measurements were carried out in thirty-four apparently healthy individuals within the same age range (mean + SE 46.3 +/- 1.1 years) and FPG <6.4 mmol/L. FPG was measured by glucose oxidase method and TAS by colorimetric method. Comparing the two groups, TAS was significantly reduced in the NIDDM patients (p<0.001). An inverse correlation between FPG and TAS suggests the existence of lower antioxidant defence in uncontrolled NIDDM. A good control of FPG accompanied with antioxidant therapy could help reduce free radical activity and minimise complications associated with increased free radical activity in diabetic patients.

Homogeneous immunoglobulins in Ghanaians living in Accra, Ghana.

Serum screening for homogeneous immunoglobulins (H-Ig) was done on 149 apparently healthy Ghanaians (aged 17-95 years) and 73 sick subjects who presented at the Korle-Bu Teaching Hospital from October 1999 to September 2000. Sera were screened by agarose gel electrophoresis and those with equivocal results were confirmed by immunoelectrophoresis. Immunoglobulin classes (IgG, IgA and IgM) and Bence Jones proteinuria were measured and determined by single radial immunodiffusion method and heating respectively. Total protein, albumin, calcium, uric acid, urea and creatinine were estimated on ACE chemistry autoanalyser. The laboratory profile of 5 Ghanaians with a picture of multiple myeloma and one with monoclonal gammopathy of undetermined significance drawn from the sick subjects (6 of 73) are presented. None of the 149 healthy subjects studied in three age groups (17-40; 41-64 and dollar 65 years) had H-Ig, and their serum IgG, IgA, IgM, urea, creatinine, uric acid, calcium, total protein and albumin levels were within the normal range. H-Ig were present in sera of 6 out of the 73 sick subjects (8.2%); 5 of them (4 males, 1 female) presented a picture of multiple myeloma. Three of these 5 patients had IgG, and the others IgA paraproteinaemia. All 5 patients had immunoparesis which was absent in the 6th patient (a male) who also had IgA paraproteinaemia (< 10 g/L), active bone marrow with < 2% mature plasma cells and no renal involvement. Results of bone marrow examination supported a diagnosis of multiple myeloma in the 3 patients with IgG paraproteinaemia, but were not available for the other two. Bence-Jones proteinuria was found in 2 (both with IgG paraproteinaemia) of 4 patients (50%) available for testing. Renal involvement was indicated in the 5 patients with a picture of multiple myeloma as urea and creatinine levels were significantly raised.

Characterisation of receptors for 1,25-dihydroxyvitamin D3 in the human testis.

Specific high affinity receptors for 1,25-dihydroxyvitamin D3 have been demonstrated in the human testes. The mean binding affinity (Kd +/- SD) of the receptor for 1,25-dihydroxyvitamin D3 was 1.75 +/- 0.32 x 10(-10) M but the binding capacity was low (mean Nmax +/- SD = 0.53 +/- 0.18 fmol/mg protein). Binding was time- and temperature-dependent, with a maximum binding achieved after 1 h at 25 degrees C. Although binding also took place at 4 and 37 degrees C, higher and more rapid binding was found at 25 degrees C. Furthermore, the binding between the ligand and the receptor was specific since only unlabelled 1,25-dihydroxyvitamin D3 competed with the labelled ligand. Binding of 1,25-dihydroxyvitamin D3 was abolished by trypsin and heat. Sucrose density gradient centrifugation revealed a sedimentation coefficient of 3.6S.

Zinc induced changes in the progesterone binding properties of the human endometrium.

The binding of progesterone to plasma and endometrial cytosol is markedly influenced by Zn++, the degree and magnitude of this influence being dependent on the concentration of the metal ion. There is a critical protein concentration (approximately 10 mg/ml) beyond which the zinc exerts either a stimulatory or inhibitory effect. Maximum increases in binding of over 60% were attained in solutions of plasma containing 30 mg of protein whereas increases of 10% were measured in cytosol specimens with 10 mg protein/ml. This metal mediated effect was however progressively diminished with increasing zinc concentration resulting finally in the return of the binding to the levels observed in the absence of added Zn++. The zinc induced inhibition was most evident in plasma and cytosol with a protein concentration less than 10 mg/ml. The magnitude of this effect was inversely proportional to the levels of protein in solution. Scatchard analysis of the data revealed that the number of progesterone binding sites in the receptor are affected by the presence of the metal while the association constants remained unchanged. The study also suggests that the zinc induced changes are partially reversed by dithiothreitol and EDTA. We believe that the metal interferes directly with the SH groups at the receptor binding sites.

Epidermal growth factor receptors in human prostate cancer: correlation with histological differentiation of the tumour.

The presence of specific and high affinity epidermal growth factor receptors (EGF-R) has been demonstrated in human prostate cancer (CaP). Scatchard analysis of the binding data revealed a linear plot consistent with a single class of binding sites with a mean dissociation constant (Kd) +/- s.d. = 1.6 +/- 0.4 nmol 1-1. Additionally the binding was specific for EGF since no other competitor than EGF was able to displace the binding of the labelled ligand from its receptor. Comparison of the concentrations of EGF-R in tissues from 19 patients with CaP with those measured in a group of 18 patients with benign prostatic hyperplasia (BPH) reveal that the expression of EGF-R was significantly higher in BPH (mean +/- s.d. = 125 +/- 7 fmol mg protein-1) than in CaP (52 +/- 11 fmol mg protein-1; P less than 0.01). Furthermore, in CaP the expression of EGF-R varied according to the histological grade of the cancer: well differentiated tumours demonstrated more receptors (84 +/- 13 fmol mg protein-1) than poorly differentiated tumours (22 +/- 5 fmol mg protein-1; P less than 0.01). Clearly the depletion in the expression of EGF receptors in CaP is a function of the histological grade of the cancer and as such EGF receptors could be used as a biochemical marker for tumour differentiation.