Systematic screening for bioactive peptides

Using simultaneous multiple peptide synthesis by the multipin approach, the feasibility of systematic large-scale pharmacological screening of peptide ligands was investigated. The method involves the assembly of small quantities of peptides (ca. 50 nmol) on plastic pins derivatized with an ester linker based on glycolate and 4-(hydroxymethyl)benzoate. These esters are stable under peptide synthesis and side-chain deprotection conditions but cleave under relatively mild basic conditions to generate peptides having C-terminal acid, amide and methylamide. A two-step approach to side-chain deprotection and cleavage from the solid support allows potentially toxic reagents to be removed (washed) from the peptide prior to cleavage. Consequently, the resulting peptide solutions can be used in bioassays with minimal processing. A series of angiotensin II and substance P analogs were synthesized and evaluated in an in vivo rat model and in vitro radioreceptor assay, respectively. Structure-activity studies on analogs of these bioactive peptides are well documented. The data obtained were consistent with that reported in the literature.

Acute unclassified leukemia originating from undifferentiated cells with the aberrant rearrangement and expression of immunoglobulin and T-cell receptor genes

To analyze the development pathways of early hematopoietic cells, we studied the rearrangement and expression of the immunoglobulin (Ig) and T-cell receptor (TCR) genes in 12 patients with acute unclassified leukemia (AUL). Leukemia cells from these patients were negative for myeloperoxidase staining and failed to express B-cell, T-cell, or megakaryocyte associated antigens. The expression of the CD7 antigen, myeloid associated antigens, or both was detected in three patients each. Ig and/or TCR gene rearrangements were detected in seven of the 12 patients, and five had rearrangement of both the Ig and TCR genes. Full length mature TCR gene transcripts were not demonstrated in most of the patients showing TCR gene rearrangements. In contrast, cells from two patients with germline configurations of the Ig and TCR genes tested expressed truncated forms of both Ig and TCR genes. These results suggest that AUL may generally originate from undifferentiated cells with an aberrant rearrangement and/or expression of the Ig and TCR genes.

Cancer incidence among medical diagnostic X-ray workers in China, 1950 to 1985

A second follow-up of 27,011 diagnostic X-ray workers in China revealed a 21% greater incidence of cancer than expected based on the experience of 25,782 physicians who did not routinely use X-rays (RR = 1.21; 95% Cl: 1.08 to 1.35). This risk is lower than the 50% excess reported previously and reflects, in part, the reduced risk among workers first employed after 1965, when hospital exposures to radiation probably were lower than in earlier years. The X-ray workers were employed between 1950 and 1985 and followed for an average of 16.1 years. Significantly elevated risks were seen for leukemia (RR = 2.4, n = 34 cases), and cancers of the esophagus (RR = 5.2, n = 19), liver (RR = 1.8, n = 65), and skin (RR = 2.8, n = 9). Cancers of the breast (RR = 1.5, n = 20), thyroid (RR = 1.7, n = 8), and bone (RR = 7.6, n = 4) also occurred more often than expected. Non-significant deficits were observed for cancers of the oral cavity and pharynx (RR = 0.6, n = 16), colon and rectum (RR = 0.8, n = 20), stomach (RR = 0.8, n = 36), and lung (RR = 0.9, n = 45). Excess risks for leukemia and esophageal cancer were seen among men but not among women. The RR for leukemia was higher for X-ray workers who began employment before 1970 than for those who started more recently and also for those who were young when employment began. The patterns of risk associated with duration of work, and with age and calendar time of initial employment, suggest that the excesses of leukemia and skin cancer, and, possibly, cancers of the breast and thyroid, were due to occupational exposure to X-rays. However, there was little evidence that radiation contributed to the increased occurrences of liver or esophageal cancers.

The quantitation of human ventricular myosin light chain 1 in serum after myocardial necrosis and infarction

To determine the clinical utility of human ventricular myosin light chain 1 (HVLC1) in the diagnosis of myocardial necrosis, we established a radioimmunoassay for serum HVLC1 using polyclonal antibodies raised against the purified human protein. HVLC1 levels were measured in sera from 110 control patients and 38 patients immediately after cardiovascular surgery and in serial specimens from 10 patients with uncomplicated myocardial infarctions. The HVLC1 assay was found to be equal in sensitivity for the first 48 hours to the CK-MB for myocardial necrosis after cardiovascular surgery and for myocardial infarction. In virtually all myocardial infarct patients, HVLC1 levels in sera rose within hours of the onset of chest pain. From thereon, two sub-trends were discerned. For many, the HVLC1 levels remain elevated for 9-12 days beyond. In some, the HVLC1 levels returned to normal levels 1-2 days after the initial rise, but became elevated again for the next 5-9 days. In either instance, the diagnosis of myocardial infarction was permitted as late as 10-12 days after the onset of chest pain which is in stark contrast to all conventionally used biochemical markers.

gamma-Glutamyl transpeptidase localization in esophageal exfoliative cytology of a chinese population at risk for carcinoma

gamma-Glutamyl transpeptidase (gamma-GT) localization in exfoliative esophageal specimens was evaluated in a population of 911 individuals aged 35 or older who lived in an area of China with a high incidence of esophageal squamous carcinoma. Of the total population, 24.4% was positive for gamma-GT. Graded histopathologic cellular classification revealed the following incidences: normal, 10.4% (43 of 413); hyperplasia, 22.0% (44 of 200); Grade I dysplasia, 42.4% (98 of 231); Grade II dysplasia, 46.0% (23 of 50); near-carcinoma, 100% (4 of 4); and squamous carcinoma, 77.0% (10 of 13). In these groups gamma-GT-positive cells were usually from normal esophageal squamous epithelium. A lower incidence of gamma-GT-positive cells was found for dysplastic cells (dysplasia grade I, 6.5% (15 of 231); grade II, 10.0% (5 of 50). The presence of gamma-GT-positive cells in normal esophageal squamous epithelium may prove useful for identification of suspect populations; the presence in dysplastic cells may serve as a diagnostic marker for patients who will soon progress to the carcinoma stage and who should receive early treatment and careful follow-up.

[Exploration between shen and ear by auditory determination in patients with renal disease]

Hearing determination of 51 cases had been made to observe and explore the TCM pathogenic relation between the collateral channels of Shen and ears. Model 51A-T72N pure tone auditional determinator was used. For each case, routine auditional determination was made after rest in bed quietly for an hour after breakfast. The determinating results were divided into normal (average hearing loss less than 15dB), low frequency, high frequency and plain-typing hearing loss.

RESULTS

Among the 51 cases, 8 cases were normal hearing (15.7%), the hearing loss cases were 43 (84.3%); 30 cases were double-ear hearing loss (58.8%); 13 cases were single ear hearing loss (25.5%). Cases of renal diseases frequently occurred among the young (in this group, average age was 29.5 years). Such high incidence was obviously non-physiological, but related to the renal disease itself. More serious hearing damage were seen and were in high frequency. Whether or not it was caused by hypoalbuminaemia, oedema and deprivation in blood vessel leading to disorder of circulation of sound sensitizen, or accumulation of toxin owing to renal dysfunction, or changing composition of endolymph influencing the hearing bristle cells, further research should be done in the near future.

Quantitative autoradiography of M2 muscarinic receptors in the rat brain identified by using a selective radioligand [3H]AF-DX 116

Muscarinic receptors of the M2 type have been studied in the rat brain using quantitative autoradiography with the selective ligand, [3H]AF-DX 116. High specific binding of [3H]AF-DX 116 was found in areas such as laminae IV and V of the parietal cerebral cortex, thalamus and hypothalamus and dentate gyrus. Intermediate [3H]AF-DX 116 binding was found in the frontal cortex, hippocampus, caudate-putamen, nucleus accumbens, and claustrum as well as in certain brainstem nuclei such as the nucleus of the solitary tract and the dorsal motor nuclei of the vagus. In contrast, the accessory olfactory nucleus, globus pallidus and cerebellum contained very low concentrations of M2 receptors. The present study demonstrates a unique regional distribution of M2 receptors in the rat brain.

Cancer among medical diagnostic x-ray workers in China

Cancer incidence among 27,011 diagnostic x-ray workers was compared to that of 25,782 other medical specialists employed between 1950 and 1980 in China. X-ray workers had a 50% higher risk of developing cancer than the other specialists [relative risk (RR) = 1.5; 95% CI = 1.3-1.7]. Leukemia was strongly linked to radiation work (RR = 3.5, n = 30). Cancers of the breast (RR = 1.4, n = 11), thyroid (RR = 2.1, n = 7), and skin (RR = 1.5, n = 6) were increased among x-ray workers employed for 10 or more years. High risks of cancers of the esophagus (RR = 3.5, n = 15) and liver (RR = 2.4, n = 48) were not consistent with a radiation effect since risk did not vary by duration of employment. This finding suggested that some differences might exist between groups of hospital workers in social class, alcohol intake, dietary habits, and other risk factors. No excess lung cancer (RR = 0.9, n = 22) or multiple myeloma (n = 0) was observed. Significant excesses of leukemia and cancers of the breast and thyroid occurred among x-ray workers first employed prior to 1960 when radiation exposures in China were high. In fact, it was not uncommon for employees to be given time off from x-ray work because their wbc count was severely depressed. These data indicated that repeated exposure to x-rays over many years can increase the risk of leukemia and several other tumors but apparently not that of lung cancer.

Himbacine recognizes a high affinity subtype of M2 muscarinic cholinergic receptors in the rat cerebral cortex

The in vitro receptor binding properties of a muscarinic antagonist himbacine have been studied in rat cerebral cortical, cardiac and ileal membranes. Himbacine displayed high affinity (KH = 2.94 nM) for 19%, and low affinity (KL = 71.2 nM) for the remaining muscarinic receptors in rat cerebral cortex. This high affinity of himbacine agrees with its affinity for the 62% of cerebral cortical [3H]AF-DX 116 binding sites (KH = 2.30 nM). The affinity of himbacine for cardiac receptors (Ki = 9.06 nM) and ileal receptors (Ki = 12.4 nM) was the same. Therefore, himbacine appears to be a high-affinity M2-selective ligand which recognizes a subtype of M2 receptors in the cerebral cortex.

Fluoride effects on the mulberry-silkworm system

Absorption and accumulation of fluoride (F) from ambient air by mulberry leaves, and its transfer and effects on silkworm development, were examined. When the concentration of F in air exceeded 1.5 microg dm(-2). day (-1), using lime filter papers as static monitors, the F content of mulbery leaves was more than 30 ppm, the threshold for injury to silkworm larvae. Fluoride-polluted mulberry leaves inhibited growth and development of silkworms. Leaves containing more than 80 ppm F severely inhibited cocoon production. Fluoride was absorbed from the atmosphere by the mulberry leaf and was transferred to the silkworm, soil, water, and back to the atmosphere, forming a cycle.

Establishment and characterization of a continuous murine uterine cervix cancer cell line metastatic to lymph nodes and lungs

The murine uterine cervix cancer (MUCC) cell line was derived from a chemically induced Kunming mouse uterine cervix cancer (U27) and maintained in culture on solid substrates for over 100 passages. Cultures were morphotypically heterogeneous and heteroploid, with a modal number of chromosomes = 80. Each cell showed at least two abnormal chromosomes. Immunogold-silver staining was positive for keratin, vimentin, and laminin but not for desmin. The population doubling time was 27.8 h with a saturation density of 3.2 X 10(5) cells/cm2 and a peak mitotic index of about 6%. MUCC cells produced colonies on tissue culture plastic (68%) and in soft agar (8%). MUCC cells were fully malignant inasmuch as they produced in syngeneic mice invasive tumors that reproducibly were metastatic to lymph nodes and lungs. The MUCC cell line is the first mouse cervix cancer cell line useful for the study of invasion and metastasis.

[3H]AF-DX 116 labels subsets of muscarinic cholinergic receptors in rat brain and heart

The in vitro binding properties of the novel muscarinic antagonist [3H]AF-DX 116 were studied using a rapid filtration technique. Association and dissociation rates of [3H]AF-DX 116 binding were rapid at 25 degrees C (2.74 and 2.70 X 10(7) min-1 M-1 for K+1; 0.87 and 0.93 min-1 for k-1) but 20-40 times slower at 0-4 degrees C (0.13 and 0.096 X 10(7) min-1 M-1 for k+1; 0.031 and 0.022 min-1 for k-1 in cerebral cortical and cardiac membranes, respectively). Kinetic dissociation constants (Kds) were estimated to be 31.8 nM and 30.9 nM at 25 degrees C; 23.1 nM and 0-4 degrees C for the cerebral cortex and heart, respectively. In saturation studies, [3H]AF-DX 116 labeled 29 percent of the total [3H](-)QNB binding sites in the cerebral cortical membranes and 87 percent in the cardiac membranes, with Kd values of 28.9 nM and 17.9 nM, respectively. Muscarinic antagonists inhibited [3H]AF-DX 116 binding in a rank order of potency of atropine greater than dexetimide greater than AF-DX 116 greater than PZ greater than levetimide in both tissues. Except for PZ/[3H]AF-DX 116 and AF-DX 116/[3H]AF-DX 116 in the cerebral cortex, all the antagonist competition curves had Hill coefficients close to one. Carbachol and oxotremorine produced shallow inhibition curves against [3H]AF-DX 116 binding in both tissues. Regional distribution studies with [3H](-)QNB, [3H]PZ and [3H]AF-DX 116 showed that most of the muscarinic receptors in the cerebral cortex, hippocampus, nucleus accumbens and corpus striatum are of the M1 subtype while those in the brainstem, cerebellum and other lower brain regions are of the M2 subtype. These results indicate that [3H]AF-DX 116 is a useful probe for the study of heterogeneity of muscarinic cholinergic receptors.

Thermodynamic analyses of pirenzepine binding to membrane-bound and solubilized muscarinic receptors from rat forebrain and heart

The thermodynamic properties of pirenzepine (PZ) binding to membrane-bound and digitonin-solubilized muscarinic receptors (mAChR) from the rat forebrain and heart were evaluated. Apparent dissociation constants (Kd) of PZ were measured from saturation studies using [3H]PZ for forebrain membrane-bound mAChR and from inhibition studies of (-)-[3H]quinuclidinyl benzilate binding using unlabeled PZ, at five different temperatures from 4 degrees C to 37 degrees C. The Kd values of PZ binding to both membrane-bound and solubilized mAChR decreased with decreasing temperature whereas the maximum receptor density was unchanged. The heterogeneity of membrane-bound mAChR characterized by PZ binding to mAChR from both tissues disappeared upon digitonin-solubilization of the mAChR. The magnitude of changes of the Kd values with temperature was greater in the solubilized mAChR, suggesting that some constituents in the membrane constrained the affinity changes. The Gibbs free energy of PZ binding to membrane-bound and solubilized mAChR were both negative. The Gibbs free energy for membrane-bound receptors decreased (more negative) whereas those for solubilized receptors increased (less negative) with increasing temperature. The change in entropy was the apparent major driving force for PZ binding to membrane-bound receptors with the change in enthalpy also being favorable. The change in enthalpy was the apparent major driving force for PZ binding to solubilized receptors at all temperatures with the change in entropy being unfavorable above 17 degrees C in the rat forebrain mAChR and above 10 degrees C in the heart mAChR. Our results suggest an important role for the biomembrane microenvironment and possible topographical differences in the binding sites which may contribute to the mechanism of muscarinic subtypes.

Solubilization with digitonin alters the kinetics of pirenzepine binding to muscarinic receptors from rat forebrain and heart

The binding properties of the putative M1 selective antagonist pirenzepine (PZ) to muscarinic acetylcholine receptor (mAChR) embedded in membranes and freed by solubilization with digitonin have been studied in the rat forebrain and heart. In the forebrain membranes, the k+1 and k-1 of [3H]PZ binding was 7.05 X 10(5) min-1 M-1 and 1.84 X 10(-3) min-1 (Kd = 3.34 nM), respectively, whereas those in heart membranes were estimated to be 1.21 X 10(5) min-1 M-1 and 7.46 X 10(-3) min-1 (Kd = 66 nM) by an indirect method. After solubilization, the kinetic parameters were determined as 3.17 X 10(5) min-1 M-1 and 2.23 X 10(-3) min-1 (Kd = 7.16 nM) in the forebrain and 2.41 X 10(5) min-1 M-1 and 1.41 X 10(-3) min-1 (Kd = 6.35 nM) in the heart. Similar dissociation constants were obtained from equilibrium saturation binding studies of [3H]PZ. Both high and low affinity binding sites for PZ were found in the forebrain membranes, whereas only one low affinity site was detected in the heart membranes. After solubilization, the inhibition curves in both tissues were better fitted to a one-site model with similar Ki values. The affinity of the agonist carbachol was decreased greatly in the heart and decreased slightly in the forebrain after solubilization to IC50 values that were similar in both tissues. Although 5'-guanylylimidodiphosphate was able to reduce the affinity of carbachol for membrane bound mAChR and to increase slightly the binding of (-)-[3H]quinuclidinyl benzilate it had no effect on ligand binding to the solubilized mAChR. The affinities of classic antagonists (-)-[3H]quinuclidinyl benzilate and atropine were not altered significantly by solubilization. Our results suggest that several different factors appear to be involved in the association and dissociation processes of PZ binding to the putative M1 (in forebrain) and M2 (in heart) mAChR in membranes. Most of these factors were separated from the receptors by solubilization under our conditions.