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Background There is in vitro evidence that T cells from allergic patients react to benzylpenicillin-human serum albumin (BP-HSA) bioconjugates. Our group has recently shown the existence of naive CD4+ T cells recognizing BP-HSA in healthy donors. However, BP-haptenated peptides from HSA participating in the immunization of allergic patients have never been identified. The purpose of the present study is to identify immunodominant BP-haptenated peptides from HSA involved in immunization of patients to BP and to refine the frequency calculation of naive CD4+ T cells recognizing BP. Methods Co-cultures were established with CD4+ T cells from non-allergic donors and mature autologous dendritic cells (DCs) loaded with BP-HSA or BP-haptenated peptides from HSA. The CD4+ T-cell response specific for BP-HSA or for individual BP-haptenated peptides was measured using an interferon-γ (IFN-γ) ELISpot assay. The frequency of BP-specific CD4+ T cells was then calculated using the Poisson distribution. BP-HSA and BP-haptenated peptides recognition by allergic patients was evaluated on peripheral blood mononuclear cells (PBMCs) using a lymphocyte transformation test (LTT). Results Results showed that BP-HSA and BP-haptenated peptides were recognized by naive T cells from 15/16 and 13/14 tested healthy donors, respectively. Most donors responded to 3 peptides with BP covalently bound on lysines 159, 212, and 525. Two of these benzylpenicilloylated peptides (lysines 159 and 525) were also found to induce PBMCs proliferation in patients with allergic reaction to penicillins. Conclusion This study identifies and characterizes for the first time the BP-haptenated peptides from HSA involved in the immunization of patients to penicillins.

This paper considers the impacts of various patterns of differential or excess mortality on the biological and statistical interpretation of 2-year rodent carcinogenicity studies. It provides suggestions on experimental design that are intended to maximize the value of such studies for carcinogenic risk assessment. Specifically, it recommends dose reduction, possibly to the level of dose cessation, when biologically feasible and considers the merits of termination of the entire study as alternatives to the commonly employed strategy of terminating particular dose groups. It then recommends statistical analysis modifications that are appropriate when these suggestions on experimental design are adopted. One of the recommended modifications is a new statistical test to determine whether a dose group exceeds the maximum tolerated dose (MTD) on the basis of mortality. While the authors provide recommendations for the most commonly occurring exigencies, they acknowledge the need for and strongly support the practice of active engagement of the appropriate regulatory agency, e.g., the FDA, prior to any action.

1. A priori knowledge of the enzyme inhibitory potential of new drug entities and the drug-metabolizing enzymes involved can be used in support of important decisions on the future progress of a drug in clinical development. 2. Important advances in the knowledge of human drug-metabolizing enzymes have largely fuelled the integration of in vitro drug metabolism and clinical drug interaction studies for use in drug development programmes. 3. The likelihood of correctly predicting in vivo drug-drug interactions appears highly dependent on selecting the correct enzyme inhibition model for use in deriving the inhibitor constant (Ki) and correctly determining the available concentration of inhibitor at the active site of the enzyme(s) of interest. 4. The uncertainty and inaccuracy of predicting the extent and duration of in vivo drug interactions currently stems from a lack of definitive models by which to assess likely substrate and inhibitor concentrations at the active site of metabolism. Additional issues contributing to the uncertainty of predicting drug interactions include assumptions of the contribution of presystemic drug extraction and the effect of inhibitors on the processes involved. 5. This review considers the practical aspects of in vitro enzyme inhibition studies and the use of in vitro-in vivo correlation approaches described in the literature to predict in vivo drug-drug interactions.

Background Drug hypersensitivity is known to rely on a drug-specific T-cell response. Amplitude of antigen-specific T-cell response is partly controlled by the size of the antigen-specific naive CD4+ T-cell repertoire, but estimate of this repertoire has never been investigated for allergenic drugs. The purpose of this study was to evaluate the frequency of benzylpenicillin-specific CD4+ T lymphocytes in healthy donors. Methods Co-cultures were established with CD4+ T lymphocytes from healthy donors and mature autologous dendritic cells loaded with benzylpenicillin coupled to human serum albumin. CD4+ T lymphocytes were stimulated once a week for 4 weeks with benzylpenicillin coupled to human serum albumin. The CD4+ T-cell response was measured using an interferon-γ ELISPOT assay. Frequency of benzylpenicillin-specific naive CD4+ T lymphocytes was then calculated using the Poisson distribution law. Results Results showed the presence of benzylpenicillin-specific CD4+ T lymphocytes in 9 of 10 tested healthy donors irrespective of their HLA typing, with a mean frequency of 0.29 cells per million of CD4+ T cells. Experiments performed on naive (CD45RA+) and on memory (CD45RO+) CD4+ T lymphocytes showed that these benzylpenicillin-specific CD4+ T lymphocytes belonged to the naive T-cell subpopulation. Conclusion This study showed for the first time the existence of naive CD4+ T lymphocytes specific to benzylpenicillin in healthy donors.

The cytochrome P450 superfamily of enzymes play a central part in the metabolism of carcinogens and anti-cancer drugs. The expression, cellular localisation, and distribution of different forms of P450 and the functionally associated enzymes epoxide hydrolase and glutathione S-transferases have been investigated in oesophageal cancer and non-neoplastic oesophageal tissue using immunohistochemistry. Expression of the different enzymes was confined to epithelial cells in both non-neoplastic samples and tumour samples except the CYP3A was also identified in mast cells and glutathione S-transferase pi was present in chronic inflammatory cells. CYP1A was present in a small percentage of non-neoplastic samples but both CYP2C and CYP3A were absent. Epoxide hydrolase was present in half of the non-neoplastic samples and the different classes of glutathione S-transferase were present in a low number of samples. In carcinomas CYP1A, CYP3A, epoxide hydrolase, and glutathione S-transferase pi were expressed in at least 60% of samples. The expression of glutathione S-transferases alpha and mu were significantly less in adenocarcinoma compared with squamous carcinoma.

The cytochrome P450, epoxide hydrolase, and glutathione S-transferase enzyme families play an important part in the metabolism of many carcinogens and anti-cancer drugs. The expression of two forms of cytochrome P450 (P450 1A and P450 3A), epoxide hydrolase and of the alpha, mu, and pi forms of glutathione S-transferase in normal colon, colonic adenomas, and adenocarcinoma of the colon were studied by immunohistochemistry. This allowed the precise cellular site and distribution of each enzyme to be determined. Expression of all the xenobiotic metabolising enzymes studied was almost wholly confined to the epithelial cells, whether in normal, adenoma or carcinoma samples, except that cytochrome P450 3A was also identified in mast cells and glutathione S-transferase pi was also present in chronic inflammatory cells. Cytochrome P450 was present in only a small proportion of normal colon samples, whereas epoxide hydrolase and glutathione S-transferase mu were identified in about half, and glutathione S-transferase alpha and pi in most normal samples. By contrast all the enzyme forms studied were expressed in virtually all adenomas and in over half the carcinomas. These results suggest that cytochrome P450 1A and cytochrome P450 3A are more specific markers of colonic neoplasia than epoxide hydrolase or glutathione S-transferases alpha, mu, and pi.

The cellular localisation of two types of allatostatin in the brain and retrocerebral complex has been studied in larvae of Lacanobia oleracea (Noctuidae) using antisera against Manduca sexta allatostatin (Mas-AS) and two members of the Y/FXFGL-NH(2) allatostatin family. The axons of two groups of Mas-AS-immunoreactive neurosecretory cells in the pars lateralis form part of the nervi corporis cardiaci (NCC 1). They exit the brain as the combined NCC 1 and NCC 2 and pass through the corpora cardiaca (CC), where they divide to innervate the corpora allata (CA) and the mandibular (salivary) gland. The presence of Mas-AS immunoreactivity in the CA is consistent with the inhibitory action of this peptide on juvenile hormone (JH) biosynthesis in L. oleracea. Immunoreactivity in the mandibular gland nerve suggests an additional, as yet unidentified role for this peptide. Cells of the pars intermedialis, the main contributors to NCC 2, do not show Mas-AS immunoreactivity. The distribution of Y/FXFGL-NH(2) immunoreactivity is different from that of Mas-AS. Although there are fewer cells in the pars lateralis, immunoreactivity is observed in certain neurones of the pars intermedialis and the tritocerebrum. Axons of these latter neurones contribute to NCC 2 and NCC 3, respectively, and, combined with those from NCC 1, result in the prominent occurrence of Y/FXFGL-NH(2) immunoreactivity in the CC, particularly in the storage lobe. The CA has far less Y/FXFGL-NH(2) immunoreactivity compared with Mas-AS. In bioassays, the Y/FXFGL-NH(2) allatostatins did not inhibit JH synthesis by CA of L. oleracea.

The triple co-localisation of peptidergic material immunoreactive to antisera raised against allatostatins of the Y/FXFGL-NH2 type, Manduca sexta allatostatin (Mas-AS), and allatotropin has been demonstrated in a single pair of anterodorsal neurones in the frontal ganglion of the tomato moth, Lacanobia oleracea (Noctuidae). Another pair of posterior neurones contain only Y/FXFGL-NH2-type allatostatin immunoreactivity. The neurites of all four cells trifurcate, and axons project to the brain in the frontal connectives and to the foregut in the recurrent nerve. Axons from the anterior neurones, within the recurrent nerve, have prominent lateral branches supplying muscles of the crop, and axons from both anterior and posterior cells show profuse branching and terminal arborisations in the region of the stomodeal valve. The brain contributes Y/FXFGL-NH2-immunoreactive material, but not allatotropin or Mas-AS, to the recurrent nerve via NCC 1+2 and NCC 3. All three peptides have a reversible effect on the spontaneous (peristaltic) contractions of the foregut (crop) in vitro. Thus, both types of allatostatin are inhibitory at 10(-12) to 10(-7) M, whereas allatotropin is strongly myostimulatory at 10(-14) M. This is the first demonstration of the gut myoinhibitory effects of Mas-AS and, taken together with the effects of Y/FXFGL-NH2-type allatostatins and allatotropin, reveals a different functional aspect to that normally attributed to these three peptides, i.e. control of juvenile hormone synthesis by the corpus allatum.

In this study we have investigated the expression of a major family of cytochrome P450, cytochrome P450IA, in human breast carcinoma. Two closely related subfamilies (or forms) of cytochrome P450IA, cytochrome P450IA1 and cytochrome P450IA2 have been identified in rat and similar forms occur in man (Ioannides & Parke, 1990). The murine monoclonal antibody RM3 used in this study recognises rat cytochrome P450IA1 and not rat cytochrome P450IA2 and recognises a single band on immunoblots of human liver

1. The results of molecular modelling of human CYP2C isozymes, CYP2C9 and CYP2C19, are reported based on an alignment with a bacterial form of the enzyme, CYP102. 2. The three-dimensional structures of the CYP2C enzymes are consistent with known experimental evidence from site-directed mutagenesis, antibody recognition and regiospecificity of substrate metabolism. 3. The variations in substrate specificity between CYP2C9 and CYP2C19 can be rationalized in terms of single amino acid residue changes within the putative active site region, of which I99H appears to be the most significant.

Microsomal epoxide hydrolase is a xenobiotic metabolizing enzyme that catalyzes the conversion of toxic and carcinogenic epoxides to less toxic dihydrodiols. The cellular localization and distribution of microsomal epoxide hydrolase were investigated for the first time in normal and neoplastic human kidney. Light microscopic immunohistochemical studies using an alkaline phosphatase-anti-alkaline phosphatase technique showed that in normal kidney there was a wide distribution of epoxide hydrolase immunoreactivity. The main localization of epoxide hydrolase immunoreactivity was to the proximal and distal tubule epithelial cells. Strong epoxide hydrolase immunoreactivity was also identified in epithelium of the collecting ducts. In addition, epoxide hydrolase immunoreactivity was present in vascular endothelial cells, including endothelial cells lining glomerular capillaries. Epoxide hydrolase immunoreactivity was identified in all the renal tumors, and in each tumor immunoreactivity for epoxide hydrolase was localized to tumor cells. Immunoblotting of both normal kidney and tumor microsomes confirmed the presence of a single protein band of molecular weight 49 KD corresponding to the molecular weight of human hepatic microsomal epoxide hydrolase.

Cytochrome P-450, epoxide hydrolase, and glutathione S-transferase (GST) all play a key role in the metabolism of chemical carcinogens, mutagens, and various anti-cancer drugs. All these functionally associated enzymes might be involved in both the development of hepatocellular carcinoma and in determining the anti-cancer drug sensitivity of such tumors.The expression of two forms of cytochrome P-450 (P-450 IA and P-450 IIIA), microsomal epoxide hydrolase, and three classes of cytosolic GST (alpha, mu, and pi) have been studied immunohistochemically in human hepatocellular carcinoma.The hepatocellular carcinomas were characterized by a consistently high expression of epoxide hydrolase and variable expression of the cytochromes P-450 and GST. Cytochrome P-450 IA and IIIA stained in 64.5% and 41.9% of the 31 hepatocellular carcinomas studied, respectively. Epoxide hydrolase was present in all tumors, and GST types alpha, pi, and mu were identified in 48.4%, 38.7%, and 74.2% of the hepatocellular carcinomas, respectively.This study showed that the expression of xenobiotic-metabolizing enzymes in hepatocellular carcinoma is complex and the presence of different xenobiotic enzymes in hepatocellular carcinoma may contribute to the intrinsic drug resistance of these tumors.

The purpose of this study was to validate an experimental method for quantifying the pain producing potential of intravenously administered solutions. Response was measured in a Broome restraint tube modified by the addition of strain gauges. Struggling caused flexion of the tube, changing strain gauge output and increasing output variance. In experiment 1, five groups of 10 male Sprague Dawley rats were given intravenous injections of 1 ml of saline, acetate, HCl, citric acid vehicles, or KCl over a 1-min period. Results showed significant increases in output variance between saline and treated groups during the infusion period. In experiment 2, five groups of five rats were given intravenous injections of saline or 0.1, 0.05, 0.025, or 0.0125 M KCl. Rats responded in a dose-dependent manner, demonstrating the sensitivity of this technique. In experiment 3, two groups of four rats were given injections of morphine sulfate (2 or 4 mg/kg, ip) prior to administration of 0.05 M KCl. Two additional groups received no pretreatment prior to administration of saline or 0.05 M KCl. Results demonstrate that morphine ablates the response to intravenous administration of KCl. This model provides information concerning the pain producing potential of intravenously delivered compounds or formulations.

Estimates of juvenile hormone (JH) biosynthesis by isolated corpora allata from adult male Periplaneta americana using a non-discriminatory partition assay suggested glandular activity levels that were comparable with the moderate to highly active rates observed in mid-gonotrophic cycle females. Parallel measurements of endogenous whole body JH titres using micro-derivatization, HPLC and GC-MS showed that male cockroaches contained less than 10% of the amount of hormone found in mid-cycle females. Radio-TLC measurements of the short-term in vitro synthetic performance of male glands failed to reveal any major differences from female corpora allata. Follow-up JH titre studies combined with surgical sectioning of the allatal nerves seemed to indicate that the corpora allata of adult male cockroaches are subject to neural inhibition in vivo.

The endogenous titres of juvenile hormone III (JH III), and the in vitro rates of juvenile hormone biosynthesis by isolated corpora allata have been measured at intervals during the reproductive cycle of adult female Periplaneta americana. There was a close correlation between the rates of JH III biosynthesis and endogenous hormone titres. Only JH III was detected in whole body extracts, and hormone titres reached a peak (mean approximately 29 ng/g) at about the mid-point of the ootheca production cycle.

Radiochemical techniques have been developed for the measurement of juvenile hormone (JH) biosynthesis by isolated corpora allata (CA) from adult female Tenebrio molitor. The method has sufficient sensitivity, using precursor of only approx. 27 mCi/mmole (1 GBq/mmole), to permit measurement on single CA, and can therefore be used to explore the relationship between CA activity and ovarian development in this species. Identification of the hormone, 2E,6E- C 16 JH has been confirmed by a combination of radio-TLC and capillary column radio-GC of the major product of the reaction and its ‘methoxyhydrin’ derivative. No incorporation into either C17- or C18-JH was found. A 1:1 stoichiometry between incorporation of [methyl-14C]-methionine and [3H]-farnesenic acid moieties demonstrates that this amino acid can be used as a mass marker to quantify JH biosynthesis in this species. It has been shown that the rate of hormone biosynthesis is reasonably constant for up to 3 hr after isolation and the influence of pH and methionine concentration have been determined. High rates of hormone production were found when CA were incubated in TC-199, special MEM, and fortified Hanks' basal salt solution, but comparatively low rates of biosynthesis were observed when glands were incubated in Grace's Lepidopteran medium, Schneider's Drosophila medium, and in a medium used by others for the culture of ovaries and prothoracic glands from T. molitor. The CA of adult female T. molitor are activated as early as 48 hr after the pupal-adult moult. Thereafter, high rates of C16JH synthesis can be demonstrated in isolated glands.

Isolated pairs of corpora allata (CA) from adult females of both Schistocerca gregaria and Periplaneta americana incorporate radioactivity from [methyl- 14 C] methionine into C 16 juvenile hormone (JH) when incubated for up to several hours, such that the rate of JH synthesis can be accurately determined. Analysis of the medium shows that CA from P. americana continue to release newly synthesised JH at constant rates for at least 5 hr, whereas those from S. gregaria may show a marked decrease in rate of JH release after 3 hr, particularly in the case of glands having high initial rates of synthesis and release. In both cases the rates of release of JH are strictly proportional to the rates of JH synthesis when measured over a period of 3 hr incubation, independent of the rate of synthesis. It is concluded that the spontaneous level of endocrine activity in glands from both these species can be faithfully quantified by precise radiochemical methods using the short-term incubation procedures described.

‘Thompson Seedless’ fruits from vines that received gibberellin or auxin treatment were separated into different maturity classes and stored at 0° for 98 days. Samples were withdrawn at about monthly intervals and soluble solids, total acidity, malic acid, arginine and proline were measured. Fruits with differing soluble solids concn had the same soluble solids content per berry. After 30 days of storage, the soluble solids concn and total acidity of non-GA3 treated fruits began to increase, probably as a result of water loss. Malic acid concn and content increased for 30 days in storage, remained stable for the next 28 days, and then decreased during the remainder of the storage period. The amino acids, arginine and proline, remained relatively constant during the 1st 58 days of storage and then increased greatly both in concn and content.

Absorption and translocation of foliar-applied 2,4-D and amitrole were studied in shoots of the Tokay grape. The major aspect of this study involved investigating the relationship of the position of the treated leaves to the fruit clusters and to the age of the clusters. The techniques of autoradiography--extraction and purification, counting, and chromatography—were used. Such studies were conducted at various periods following application, the maximum time lapse being 112 days. Physiological significance of the findings is discussed, and practical aspects are considered.

14C-ethephon applied to a walnut leaflet penetrated and translocated rapidly in young plants, but more slowly in older plants. The compound translocated to the kernel at higher levels when applied to a leaflet than when applied to the hull but in both cases levels of activity were low. Between 5 and 7 days after application the radioactivity in the kernel decreased markedly, 14C-ethephon in the leaves, hull, shell, and kernel was metabolized, but no side products remained in the plant tissue that could be detected by the techniques employed.

SummaryGibberellic acid (GA) and the auxin, 4 chlorophenoxyacetic acid (CPA), differ in their effects upon berry enlargement in two seedless varieties of Vitis vinifera L., cv. Black Corinth and Thompson Seedless. Although initially both substances cause nearly equal increases in berry growth rates, at maturity GA-treated berries far surpass those treated with CPA. The growth rate of CPA-treated berries declines, relative to that of the GA group, two to seven days after treatment. The results of experiments in which berries received treatment with both GA and CPA show that CPA may act as an inhibitor of GA-induced expansion, particularly during the later stages of enlargement. Also, GA-treated berries have a greater length-to- width ratio than CPA-treated berries. Thus, there are apparently qualitative differences in mode of action between the two substances. Increase in berry size, regardless of treatment, is the result of water uptake accompanied by solute storage and synthesis of cell components. Histo...

Summary. High concentrations of 2,4-D and picloram interfered with the downward movement of 14c-assimilates infield-grown vines. The interference in translocation was appreciably greater with picloram than it was with 2,4-D, Although basipetal translocation was retarded, translocation within the treated shoots continued from the vegetative part to the clusters. Translocation of 2,4-D appeared to follow the same route as 14c-assimilatcs for the most part. Formative effects were absent on untreated grape shoots although the adjacent shoots treated with 2,4-D or picloram on the same cordons were killed; however, formative effects were evident on some of the stump sprouts which developed after the vines were harvested. The malformed leaves on the stump sprouts were twelve or more nodes from the base of the shoots, while 14c was in the more basal leaves. Thompson Seedless (Sultanina) rootings treated with 20 000 ppm 2,4-D or picloram transported less 14C to the roots than did the controls. Treatment with either herbicide resulted in a marked increase in the labelling of the stems. Effet du 2,4-D et du pichlorame sur la migration de metabolites marques au 14C dans Vitis vinifera L. Resume. II a ete ohserve que des concentrations elevees de 2,4-D et de pichlorame Interferaient avec le mouvement vers le bas de metabolites marques au 14c dans des vignes cultivees en plein champ. L'interference dans la migration fut nettement plus importante avec le pichlorame qu'avec le 2,4-D. Bien que la migration basipete fut retardee, la migration a travers les parties aeriennes traitdes se poursuivait jusqu'aux grappes. La migration du 2,4-D parut pour la plus grande part suivre les memes voies que les metabolites marques au 14c. II n'y cut pas d'effets morphogenes sur la vegetation non traitee alors que les parties adjacentes traitees avec le 2,4-D ou le pichlorame sur les memes souches furent tuees; toutefois, des effets morphogenes furent evidents sur certaines pousses developpees apres la recolte, Les feuilles deformees sur ces pousses se situaient a au moins douze nœudsdeta base des pousses bien que le 14C fut present dans des feuilles plus basales. Des boutures de Thompson Seedless (Sultanina) traitees avec 20 000 ppm de 2,4-D ou de pichlorame transfererent moins de 14c dans leurs racines que les temoins. Le traitement avec I'un ou I'autre de ces herbicides provoqua un accroissement marque de la radioactivity dans les tiges. Einfluss von 2,4-D und Picloram auf die Translokation 14c-Assimilaten in Vitis vinifera L. Zusammenfassung. Hohe Konzentrationen von 2,4-D und Picloram beeinflussten die Ableitung von 14C-Assimilaten in Freiland-Reben. Die Beeinfiussung der Translokation war wesentlich starker bei Picioram als bei 2,4-D. Obgleich die basipetale Translokation gehemmt war, erfolgte innerhalb der behandelten Sprosse eine Ableitung von den vegetativen Teilen in die Trauben. Die Translokation von 2,4-D schien in den meisten Fallen denselben Weg zu nehmen wie die 14C-Assimilate. An unbehandelten Sprossen wurden keine formativen Effekte festgestellt, obgleich die benachbarten Sprosse, die mit 2,4-D oder Picloram behandelt worden waren, abgetatet wurden; formative Effekte konnten jedoch an einigen der Stockausschlage nath der Traubenernte beobachtet werden. An diesen Schosslingen waren bis zwolf und mehr Nodien von der prossbasis entfernte Bla tter noch verformt, wahrend 14C mehr in den tiefer stehenden Blattern gefunden wurde. Thompson Seedless (Sultanina) Stecklinge, die mit 20 000 ppm 2,4-D oder Picloram behandelt worden waren, transportierten weniger 14c in die Wurzeln als die Kontrollen. Dagegen hatte eine Behandlung mit einem der beiden Herbizide in jedcm Fall eine starke Zunahme des 14C im Spross zur Folge.

Tokay vines were sprayed, at different stages of development, with 2,4-D at 2 and 8 ppm, in 1958, 1959, and 1960. The effects from 2,4-D varied from year to year, with much injury in 1958 and 1959, and little or none in 1960. There was little or no cumulative injury from low concentrations from one year to the next. Most malformed foliage occurred from sprays applied when shoots were about 1 foot long and from sprays applied at the bloom or shatter stage. These sprayings were also most injurious to fruit. Only extremely low concentrations of 2,4-D were found in fruit of sprayed vines, and only in berries sprayed in 1960 either at the shatter stage or at the final spraying.

Vines of Vitis vinifera ‘Black Corinth’ were sprayed with 100 ppm gibberellin A3 (GA3), 50 ppm 4-chloro-phenoxyacetic acid (4-CPA), or 1000 ppm benzyladenine (BA) about 5 days after anthesis. The concentrations of protein, RNA, and DNA in the berries were measured at 0, 1, 6, 12, 24, 48, and 96 hr after treatment. In the fruits treated with GA3 or 4-CPA, protein, RNA, and DNA were markedly increased compared to untreated fruits during the first 24 hr after treatment; thereafter, concentrations did not significantly differ from those of the control berries. Fruits treated with BA, on the other hand, had significantly higher levels of these substances only at 1 and 6 hr post treatment.

The rates of juvenile hormone (JH) biosynthesis have been measured in vitro for individual members of the paired corpora allata (CA) in the cockroach Periplaneta americana during the first two reproductive cycles. A marked similarity of endocrine activity between left and right glands of the majority of animals was observed, even though total JH biosynthesis by the gland pairs can differ up to 200-fold during this period. In a small number of immature females only one gland in the pair had the capacity to synthesize hormone. These results support the use of 'split pairs' of CA from mature, adult female P. americana in short-term in vitro radioassay of potential exogenous and endogenous modulators of JH biosynthesis, such that each sample bioassayed has a valid control. Furthermore, the observations suggest that, after a short postecdysial period (up to 4 days), the CA of this species are controlled by one or more humoral factors.

SUMMARYSeveral of the pathophysiological responses made by the beetle Tenebrio molitor, when infected with metacestodes of Hymenolepis diminuta, may be attributed to a parasite-induced reduction in host juvenile hormone titre. It has been suggested that production of this hormone by the corpora allata may be inhibited in parasitized insects. This hypothesis was tested using an in vitro radiochemical assay to compare the biosynthesis of juvenile hormone by single pairs of corpora allata taken from mated 12- and 15-day-old infected and control female insects. The results demonstrate, however, that there was no difference in hormone production associated with metacestode infection. Other possible mechanisms for parasite interference in this host endocrine system are discussed.

4,4'-Methylenedianiline (MDA) is an important chemical intermediate in the production of isocyanates and polyurethane elastomers and polymers. The health hazards from acute inhalation exposure to the aerosols were evaluated. Guinea pigs of albino and pigmented strains were exposed nose-only to the aerosols of MDA in polyethylene glycol 200 (PEG) solution. The exposure was 4 hr per day, 5 days per week for a total of 10 exposures in 2 weeks. The time-weighted average aerosol concentration was 0.44 +/- 0.09 mg/liter and the optical number length mean diameter of the aerosol particle was 2.4 micron with sigma g of 2.1. During exposures, no overt respiratory distress was observed. Two weeks after the exposures, the guinea pigs were tested for possible dermal sensitization by being challenged with dermal application of MDA-PEG solutions at concentrations of 0, 2, 20, and 200 mg/ml. Neither dermal irritation nor allergic response was detected under this experimental condition. Thereafter, the animals were tracheostomized for measurements of changes in lung insufflation pressure for detecting possible changes in the distensibility of the lungs from a challenge dose of an aerosol of MDA-PEG at a concentration of 200 mg/ml. No significant changes were observed under this testing condition. Finally, the animals were euthanized for histopathologic examinations of eye, lung, liver, and kidney. The most remarkable findings was the degeneration of the inner and outer segments of the photoreceptor cells and the pigmented epithelial cell layer of the retinas of both albino and pigmented strains of guinea pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Durch Inkorporation von14C-Methionin in die Corpora allata vonPeriplaneta americana werden wahrend des Eireifungszyklus zwei Aktivitatsmaxima festgestellt und diese als Juvenilhormonsynthese interpretiert.

The discovery by Roller and Dahm (1970) that significant quantities of juvenile hormone could be isolated from cultures in vitro of corpora allata from the adult moth Hyalophora cecropia heralded the approach of a new era of experimental investigations of the physiology of the insect corpus allatum, since it showed that the glands continued to make and release the hormone after removal from the body and therefore might be amenable to direct observation in this way. Standard organ culture procedures for the production of relatively pure preparations of juvenile hormones biosynthesized in vitro, were then employed in conjunction with specially developed analytical procedures by workers in two other laboratories, so as to identify which of the three known juvenile hormone homologs were produced by the corpora allata of the adult female of several insect species (Judy et al., 1973a,b; 1975; Jennings et al., 1975; Muller et al., 1974). K.J. Judy and his co-workers also employed to their advantage in identifying the homologs, the efficient and relatively specific incorporation of radioactivity from the S-methyl group of methionine into the methyl ester of juvenile hormones, previously discovered during experiments on H. cecropia in vivo by Metzler et al. (1971).

Source-to-sink movement of plant assimilates usually involves the transfer of substrate materials from green, photosynthesizing assimilating tissues to growing regions or storage organs. Mason and Maskell (1928), who measured carbohydrate fractions in fruits, stems, and leaves of cotton at various times during the day, did much to develop the source-to-sink concept for assimilate movement.

Surgical removal of the ovaries from nymphalPeriplaneta americana results in lower than normal corpus allatum activity in the adult insect and an apparent absence of the manifestly cyclic pattern of juvenile hormone biosynthesis found in intact mated females. The results suggest that the presence of synchronously developing ovaries is necessary for the attainment of normal synthetic activity in the corpus allatum of this species.

The method was based on the minimum dosage of 2,4-dichlorophenoxyacetic acid (2,4-D) that would produce strap- ping or cupping of cotton leaves. Dilutions of an unknown were applied to cotton cotyledons. The minimum dosage required to produce strapped or cupped leaves two weeks later was approxi- mately 0.05 tg/plant. The results of this bioassay were comparable to tracer methods, but the latter can detect smaller quantities of 2,4-D.