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Psychological distress following cancer diagnosis may lead to mental health complications including depression and anxiety. Non-Hodgkin lymphomas (NHLs) include indolent and aggressive subtypes for which treatment and prognosis differ widely. Incident use of psychotropic drugs (PDs - antidepressants, antipsychotics, and anxiolytics) and its correlation to lymphoma types can give insights into the psychological distress these patients endure. In this prospective matched cohort study, we used nationwide population-based registries to investigate the cumulative risk of PD use in NHL patients compared to a sex- and age-matched cohort from the Danish background population. In addition, contact patterns to psychiatric departments and incident intentional self-harm or completed suicide were explored. In total, 8,750 NHL patients and 43,750 matched comparators were included (median age 68; male:female ratio 1.6). Median follow-up was 7.1 years. Two-year cumulative risk of PD use was higher in NHL patients (16.4%) as compared to the matched comparators (5.1%, p

The development of a long-term research program on the neurosecretory hormones of arthropods is described. The purification and full characterization of the first invertebrate neurohormones, the red pigment-concentrating hormone (RPCH) and the distal retinal pigment hormone (DRPH) demonstrated that they are peptides, an octapeptide and an octadecapeptide, respectively. Physiological function studies with the pure hormones and their synthetic preparations showed that the RPCH acts as a general pigment-concentrating hormone (PCH), and that the DRPH, in addition to its light-adaptive function, also constitutes a general pigment-dispersing hormone (PDH). In the regulation of the color-adaptation of the animals, the two hormones act as antagonists. The chromatophorotropic activities are widely distributed within the arthropod neuroendocrine systems. Purification of the pigment-concentrating activities from the locust corpora cardiaca lead to the isolation and characterization of the first insect neurohormones, the adipokinetic hormones (AKH I and AKH II). These two hormones, AKH I being a decapeptide and AKH II being an octapeptide, are close structural analogs to the crustacean PCH, demonstrating a common evolution of arthropod neurohormones. The hormones of this PCH-family all cross-react, but structure-function studies of the hormones show that quite different parts of their structure are involved in their binding to the various receptors.

The effects of either cation removal or ionic channel blockade were determined on the dose-response curve (DRC) to PCH (pigment-concentrating hormone) in Macrobrachium potiuna erythrophores. In sodium-, potassium- and calcium-free salines, the pigment-aggregating responses to PCH were depressed; in the former condition, maximal aggregation was not achieved and the slope of the regression curve determined from the DRC was significantly different from control. Tetrodotoxin, verapamil or tetraethylammonium (TEA) treatments also diminished the pigment-aggregating responses to PCH, and the slopes of the regression curves were different from control in the presence of 10 −6 M verapamil or 10 −6 M TEA. Interestingly, the DRC determined in the absence of both sodium and calcium ions was not significantly different from control. When verapamil was applied in sodium-free conditions, maximal aggregation was prevented. The erythrophore resting membrane potential ranged from −62 mV to −78 mV and did not vary during PCH-induced pigment aggregation as compared to the control. Our results suggest that transient modifications of potassium equilibrium potential may interfere with PCH signal transduction, revealing a more relevant role of potassium in the process, and that a sodium influx and an intracellular calcium mobilization are necessary to maintain a cytosolic balance between the ions for normality of PCH-induced responses.

Purification of the first dipeptidases, glycylleucine dipeptidase (EC 3.4.13.2) and proline dipeptidase (EC 3.4.13.9), from intestine, have shown them to be true dipeptidases, hydrolysing only dipeptides in their laevo form. Although they have quite different specificities they show great similarities in their chemical and physicochemical properties. Specific antibodies against the two dipeptidases have been raised and used in combination with the double-layer immunofluorescent staining technique to study their histological localization in the small intestine. The results conclusively demonstrated that both glycylleucine dipeptidase and proline dipeptidase are exclusively located in the cytosol of the enterocytes. This location fits well with the current idea of transport and hydrolysis of dipeptides in the intestine where the dipeptides are taken by a specific transport mechanism and are hydrolysed intracellularly. Although it is tempting to add a specific role for the dipeptidases of the enterocytes in the final digestion of exogenous proteins, studies so far have shown their identity with the corresponding dipeptidases of other tissues. It is therefore suggested that their role in the digestion process may be based entirely on their abundance in the intestine.

An in vitro crustacean (freshwater shrimp, Macrobrachium potiuna) erythrophore bioassay for chromatophorotropins and other pigment cell agonists is described. The present assay is a quantitative method that determines the pigment responses with the aid of an ocular micrometer. The pigment granules within the erythrophores are dispersed out into the dendritic processes of the cells when the isolated carapace is placed in physiological solution. This bioassay provides, therefore, a method for measuring the response of the pigment cells to aggregating agents such as pigment concentrating hormone (PCH). This bioassay is sensitive to PCH at a concentration as low as 3 x 10(-12) M. Calcium ionophore A23187 mimics the actions of PCH, but, unlike the hormone, the ionophore-induced pigment aggregation is irreversible after physiological solution rinses. Therefore, chromatophorotropic activities of pigment dispersing agents, such as pigment dispersing hormones (PDH), can be determined on ionophore-treated erythrophores. The potencies of alpha-PDH and beta-PDH show a threefold difference (not significant). Because of its convenience and its ability to make an objective determination of the bidirectional pigment movements within erythrophores, this bioassay is a suitable method for further structure-activity studies of the various chromatophorotropins and their analogs.

This chapter contains sections titled: Introduction Mechanical Considerations Radiation Patterns Array Impedance Polarization Characteristics of Selected Conformal Arrays References ]]>

This chapter contains sections titled: Introduction Aperture Antennas Microstrip-Patch Antennas References ]]>

This chapter contains sections titled: Introduction Fundamentals Phase Mode Theory The Ripple Problem in Omnidirectional Patterns Elevation Pattern Focused Beam Pattern References ]]>

This chapter contains sections titled: Introduction Shape Optimization Fourier Methods for Circular Ring Arrays Dolph-Chebysjev Pattern Synthesis An Aperture Projection Method The Method of Alternating Projections Adaptive Array Methods Least-Mean-Squares Methods (LMS) Polarimetric Pattern Synthesis Other Optimization Methods A Synthesis Example Including Mutual Coupling A Comparison of Synthesis Methods References ]]>

This chapter contains sections titled: Introduction Aperture Antennas on Circular Cylinders Aperture Antennas on General Convex Cylinders Aperture Antennas on Faceted Cylinders Aperture Antennas on Dielectric Coated Circular Cylinders Microstrip-Patch Antennas on Coated Circular Cylinders The Cone References

This chapter contains sections titled: Introduction Singly Curved Surfaces Doubly Curved Surfaces Arbitrarily Shaped Surfaces References ]]>

This chapter contains sections titled: Introduction Definitions Radar Cross Section Analysis Cylindrical Array Cylindrical Array with Dielectric Coating Radiation and Scattering Trade-off Discussion References ]]>

The cellular system responsible for the transduction of the pigment-concentrating hormone (PCH) signal was investigated in erythrophores of the freshwater shrimp, Macrobrachium potiuna. Dose-response curves to the hormone were determined in the absence and in the presence of several drugs that affect sequential steps of the Ca(2+)-dependent signalling pathway. Additionally, the ability of forskolin to induce pigment dispersion was evaluated. Neomycin sulphate (10(-4) and 10(-3) mol.l-1), trifluoperazine (10(-5) and 10(-4) mol.l-1), 1-(5-isoquinolinesulfonlyl)-2-methylpiperazine (10(-7) and 10(-5) mol.l-1) and okadaic acid (10(-7) mol.l-1) significantly (P0.05) decreased the responses to PCH. However, okadaic acid at low concentration (10(-9) mol.l-1) and cyclosporin A (10(-6) and 10(-5) mol.l-1) did not significantly (P0.05) affect PCH activity. Forskolin (10(-4) mol.l-1) was able to half-maximally reverse the hormone-induced aggregation. Our results suggest that the pigment-concentrating hormone induces pigment aggregation through a Ca(2+)-dependent pathway with a posteriori phosphatase activation, probably the serine/threonine phosphatase 1.

Herein we report the effects of microtubule- and actin-like filament disrupting drugs, as well as the microtubule stabilizer taxol, on PCH-induced pigment granule aggregation within erythrophores of the freshwater crustacean Macrobrachium potiuna. Dose-response curves (DRCs) to the pigment-concentrating hormone PCH were determined under control and experimental conditions to evaluate the effects elicited by the cytoskeleton-affecting drugs. Colchicine, at temperatures 22 degrees C and 4 degrees C, and vinblastine significantly inhibited the aggregating response to PCH and affected the dynamics of the process, as shown by the change in the slope of the regression curve calculated from the DRCs. Lumicolchicine, a colchicine analogue with no affinity for tubulin, also inhibited pigment migration, though no change in the slope of the regression curve was observed. The inhibitory effects of lumicolchicine demonstrate that changes in sites other than cytoskeleton, such as membrane permeability, may also cause a decrease in the PCH-induced aggregating responses and that the colchicine effects may result from its action on cellular sites additional to the cytoskeleton. Taxol, a microtubule stabilizer, did not affect the DRC to PCH, and DMSO improved the PCH-evoked responses, pointing out to the maintenance of tubulin in the polymerized state as the appropriate condition for aggregation. Cytochalasin B, an actin-like filament disrupter, diminished the aggregating responses to the hormone, with no change in the slope of the regression curve, indicating that these elements take part in the process and that cytosolic calcium rise, sol/gel transformations and endoplasmic reticulum motility may well play an important role in granule migration. It is suggested that microtubules are steadily polymerized as a requirement for pigment aggregation and that process is biphasic, the initial phase being dependent on the microtubule integrity.

An analysis of an array of rectangular waveguide openings in a circular cylindrical ground plane covered with a radome is presented. The analysis method is based on the modal solution, i.e. on the superposition of one-dimensional spectral solutions, and on the moment method. The modal approach requires the summation of a large number of terms in the Fourier series for structures with large radii. Furthermore, highly oscillating integrals occur when the waveguide openings are axially separated. Both problems are treated with special care: asymptotic formulas are used for calculating the Green’ s functions, and the integration contour for calculating the inverse Fourier transformation is carefully selected. Measurements on a 18x3 waveguide array on a circular cylindrical structure covered with a radome have been used for verification of the theoretical results. The effect of an air-gap between the waveguide openings and the radome is discussed. The agreement between calculated and measured values of mutual coupling, input admittance and radiation patterns is very good.

The red pigment-concentrating hormone of the eyestalks of the prawn Leander adspersus has been purified. It is an octapeptide with the following amino acid composition: Asp1, Glu1, Gly1, Leu1, Phe1, Pro1, Ser1, Trp1. The complete identity in purification behavior, in amino acid composition, in electrophoresis, and in partition chromatography with the previously purified red pigment-concentrating hormone from the prawn Pandalus borealis, strongly indicate structural identity between the hormones of the two species.

Purification of prolidase (imidodipeptidase, EC 3.4.3.7) from pig small intestine is described. Two alternative purification procedures have been developed, one of which utilizes the capability of the enzyme to aggregate to high molecular weight complexes and allows purification of 20 mg of prolidase in each preparation. The purity of the prolidase was found to be more than 99% when tested on polyacrylamide electrophoresis, and it showed homogeneity in crossed immunoelectrophoresis. The enzyme has a specific activity of about 200 units of activity per mg protein when determined against l -alanyl- l -proline. The specificity of the enzyme is in accordance with the original definition of an imidodipeptidase, as its activity is limited to dipeptides with the constitution aminoacyl- l -proline or aminoacyl- l -hydroxyproline, and it has no activity against tripeptides.

The red pigment-concentrating hormone (RPCH) from crustacea is an octapeptide with the following structure: pGlu-Leu-Asn-Phe-Ser-Pro-Gly-Trp-NH 2 , [4-Tyr]RPCH has been synthesized and was 4 times as active as RPCH in the Leander assay. Iodination of the hormone analog using chloramin-T, lactoperoxidase, solid-state lactoperoxidase, and thallium chloride was carried out and the results were compared. 125 I-labeled [4-Tyr]RPCH was prepared using a modificated chloramin-T method and was purified from unlabeled and diiodinated peptide by chromatography on Sephadex LH-20.

A new peptide with both adipokinetic activity in the locust and red pigment-concentrating activity in the shrimp, can be readily separated from the adipokinetic hormone in extracts of corpora cardiaca (CC) from Schistocerca americana gregaria by the use of gel chromatography and the Leander adspersus bioassay. The new peptide accounts for 20% of the total biological activity in locust CC, and it is located principally in the CC glandular lobe. The amino acid composition of the pure peptide is: Asp, Thr, Ser, Glu, Gly, Leu, Phe, Trp. This composition is similar to, but not identical with the red pigment-concentrating hormone of the shrimp.

The crustacean pigment-translocating hormones, the red pigment-concentrating hormone (RPCH), an octapeptide, and the light-adapting distal retinal pigment hormone (DRPH), an octadecapeptide, are the first invertebrate neurohormones to be fully characterized. Studies with both purified and synthetic hormones show that, in certain decapods, RPCH is a general pigment-concentrating hormone (PCH), affecting the pigments of all kinds of chromatophores (erythrophores, xanthophores, leucophores and melanophores); the DRPH seems to serve not only light-adapting function, but also act as a general chromatophore pigment-dispersing hormone (PDH). The two hormones thus function as antagonists when regulating the color-adaptation of the decapod crustaceans. PCH activity is widely distributed within the arthropod endocrine systems. The first characterized insect neurohormones, the locust adipokinetic hormones (AKH I and AKH II), show close structural similarities to the crustacean hormone, indicating a common evolution of some of the arthropod neurohormones. Physiological studies of the three hormones (RPCH, AKH I, and AKH II) and their synthetic analogs show that they crossreact, i.e., they all exhibit pigment-concentrating activity when tested on decapod crustaceans, adipokinetic activity when tested on locusts, and hyperglycemic activity when tested on cockroaches, although each of the hormones is more potent in its own system. Structure-function studies show, however, that quite different binding-site requirements exist for the hormones in activating their receptors on the various target tissues. The physiological specificity in their action therefore seems to depend on a differential evolution of the hormone receptors.

Antibodies were raised in rabbits against glycylleucine dipeptidase (EC 3.4.13.2) and proline dipeptidase (EC 3.4.13.9) purified from the pig. IgG fractions were isolated and purified by affinity chromatography on Sepharose (dipeptidase) columns and then used in histological studies on the small intestine and the liver from pig, using the double layer immunofluorescence-staining technique. In the small intestine the dipeptidases were predominantly localized in the cytoplasm of the enterocytes. A reaction was also seen in the leukocyte cytoplasm in the stroma of the small intestine. The dipeptidases were present in the villi but not in the crypts. In the liver the dipeptidases were localized, in the cytoplasm of the hepatocyte, but strong fluorescence was also obtained in the epithelium of the bile ducts. Glycylleucine dipeptidase and proline dipeptidase have been isolated from liver tissue and they were shown to be immunologically identical with the purified intestinal dipeptidases.

1. Red pigment concentrating hormone-like activity (RPCA) has been demonstrated and quantified in the head or cephalic neuroendocrine system of several insects. Schistocerca gregaria adults contained the highest levels of RPCA.2. RPCA was found in all post-embryonic life cycle stages of S. gregaria, and seems to be present in equal quantities in both males and females. Adult locusts contain significantly more RPCA than do immature animals.3. RPCA is concentrated in the locust CC glandular lobe hut is also present in the CC storage lobe, brain and hemolymph of both mature and immature animals. Significant variations in CC RPCA content have been demonstrated in both mature and immature stages.4. Synthetic red pigment concentrating hormone (RPCH) is adipokinetic in both intact and neck-ligatured S. gregaria adults and in intact immature animals. Doses of about 6 ng and 50 ng, respectively, result in minimal and maximal adipokinetic responses. RPCH selectively elevates hemolymph 1.2-diglycerides.5. RPCH in la...

The significance of the C-terminal tryptophan residue of the red pigment-concentrating hormone (RPCH: Glu-Leu-Asn-Phe-Ser-Pro-Gly-Trp-NH2) regulating the blanching of the crustacean chromatophores has been investigated. RPCH and a number of analogues that differ only in the C-terminal part of the hormone, have been synthesized and assayed for biological activity on the shrimp Leander adspersus. It has been shown that the indole skeleton of tryptophan is an absolute requirement for the biological activity of the hormone. To provide maximum response the tryptophan must be blocked as the amide. The activity of synthetic [Tyr4]RPCH and adipokinetic hormone (AKH) purified from Schistocerca gregaria has been compared with the activity of synthetic RPCH.

Purification of a soluble dipeptidase (EC 3.4.3.2) from pig small intestine is described. 10–20 mg of the purified enzyme were obtained in each preparation (30 m small intestine). It was tested to be at least 99% pure on polyacrylamide electrophoresis and homogenous in crossed immunoelectrophoresis. The specific activity of the enzyme, estimated against glycyl- l -leucine, varied between 1400–1700 units of activity per mg protein in different batches. The enzyme has a wide specificity against dipeptides, although it has no prolidase activity. Among the dipeptides tested, l -alanyl- l -alanine, l -alanyl- l -serine and glycyl- l -leucine were hydrolyzed most rapidly. The enzyme constitutes a true dipeptidase, as it has no tripeptidase or arylamidase activities. It is strictly stereospecific and requires free end-groups of the dipeptides. No activity of the enzyme was found against dipeptides containing β-amino acids.

Five dipeptidase activities in the mucosa of the rat small intestine have been determined and characterized by the aid of a new spectrophotometric assay method.The distribution of the dipeptidase activities along the gastrointestinal tract has been investigated. The activities were low in the stomach, the cecum and the large intestine, while high activities were found along the whole length of the small intestine with the maximum localized to its middle part. The relation of our present findings to previous observations about the rat intestinal dipeptidases has been discussed. Some differences with respect to both their properties and their distribution were observed in com- parison with the dipeptidases of the pig intestinal mucosa.

1. 1. A method for the semiquantitative determination of microamounts of nucleic acid derivatives, utilizing the thin-layer adsorbent chromatographic technique, is described. 2. 2. The method is of a very high sensitivity (7·10 −5 μmoles) and rapidity, and permits of a wide application. 3. 3. In addition to the determination of nucleic acid derivatives the technique can be utilized for other compounds having a strong absorption in the ultraviolet region.

The volume changes accompanying some proton transfers, the O,N-acyl shift in O-acetyl- DL -serine and the reactivation of anhydrous formic acid-inactivated ribonuclease are reported. The results strongly suggest a deformylation of the hydroxyamino acid residues as the main reaction in the reactivation process. However, from the results it is not clear whether the formyl groups are bonded in an ester or formamide linkage. A simple method for preparation of N-acetyl- DL -serine is described.

Summary 1. A study has been made of the distribution of L -alanyl- L -glutamic acid dipeptidase, glycylglycine dipeptidase (EC 3.4.3.1), glycyl- L -leucine dipeptidase (E.C 3.4.3.2) and glycyl- L -valine dipeptidase along the small intestine of adult pig. 2. With the exception of the most proximal part of the duodenum, activities were present along the whole length of the intestine. They all showed a rather wide zone of maximum activity including the distal part of the jejunum and the proximal part of the ileum. 3. The relative activities of the individual enzymes were found to vary greatly. 4. The relation of these findings to protein absorption is discussed.

1. 1. ‘Red-pigment-concentrating hormone’ and distal retinal pigment hormone from aqueous extract of lyophilized eyestalks of Pandalus borealis have been separated on Sephadex G-25. 2. 2. Low activity yields (30%) of the distal retinal pigment hormone were increased by combining the active material with separated inactive material. 3. 3. Final purification of the ‘red-pigment-concentrating hormone’ has been achieved by repeated chromatography on Sephadex LH-20 using different mixtures of water and butanol as solvent. 4. 4. The purified ‘red-pigment-concentrating hormone’ has a specific activity of 1.7·10 6 times that of dry eyestalks. The total recovery of hormone activity was about 35%. 5. 5. A reference standard for the ‘red-pigment-concentrating hormone’ is described and a unit of ‘red-pigment-concentrating hormone’ is defined. 6. 6. The hormone is a peptide containing the eight amino acids, aspartic acid, glutamic acid, glycine, leucine, phenylalanine, proline, serine and tryptophan. 7. 7. No N-terminal amino group has been found. 8. 8. Large and small erythrophores in Palaemon adspersus are both affected by this hormone.

A method is described for the isolation of morphogenetic substances from mature, unfertilized eggs of the sea urchin Paracentrotus lividus. A complete separation of several different substances with specific animalizing or vegetalizing effect on the early development of sea urchins, when tested on whole eggs and on isolated animal and vegetal halves, was achieved by chromatography on Dowex 50 W-X2 and on Sephadex G-25. The results suggest that developmental processes can be influenced by various types of substances that may preexist in the unfertilized eggs. Two of the animalizing substances were obtained extensively purified. According to their ultraviolet absorption curves, on may contain tryptophan and the other consist of a nucleotide. They both exhibit a very high specific activity but differ significantly in their morphogenetic specificity. One induces strong animalization when tested on animal halves but has no effect when tested on whole eggs or on vegetal halves. In contrast, the other shows a strong animalizing activity in all three test systems. The high specific activity of the purified animalizing substances is demonstrated by their ability in very low concentrations to force the animal halves into their most extreme animal type of differentiation, i.e., with stereocilia all around the blastula wall, and to induce a differentiation on the vegetal halves not only to plutei but to a new extreme animalized larval type, the radial type. This type of vegetal half is characterized by the presence in the early stages of an apical tuft, and a further development with a thick ectoderm covering about half the body and with the skeleton in equatorial and radial position.

Josefsson, L., O. Noren and H. Sjostrom. Comparison of dipeptidase activity in different tissues of the pig. Acta physiol. scand. 1968. 72. 108–114. A comparative investigation of three dipeptidase activities (L-alanyl-L-glutamic acid. L-alanyl-L-proline and glycyl-L-leucine dipeptidase activity) of the trachea, the tuba uterina, the uterus and the small intestine of the pig has been made to study if the intestinal dipeptidasrs differ in their characteristics from the dipeptidases of other tissues. No indication was obtained supporting the idea that the intestinal dipeptidases would be different and constitute a group of conzymes, particularly adapted for intestinal digestion.

1. 1. A method is described for the purification of a ribonuclease (polyribonucleotide 2-oligonucleotide transferase (cyclizing), EC 2.7.7.16) from mature, unfertilized eggs of the sea urchin Psammechinus miliaris . The enzyme was purified 19 000-fold with a yield of 48% with the aid of chloroform treatment, (NH 4 ) 2 SO 4 fractionation, and by chromatography on Sephadex G-100, on SE-Sephadex C-50 and on CM-Sephadex C-50. 2. 2. The enzyme had a pH-optimum at 5.3–5.5. 3. 3. The enzyme was heat labile, loosing about 50% of its activity in 3 min at 60° and pH 5.3, 70% of its activity in 3 min at 60° and pH 2.1, and 80% of its activity in 3 min at 40° and pH 9.0. 4. 4. The enzyme hydrolyzed yeast RNA completely to 2′,3′-cyclic nucleotides, and finally hydrolyzed the purine cyclic nucleotides slowly to their corresponding 3′-isomers. 5. 5. The enzyme hydrolyzed guanosine 2′-3′-cyclic phosphate about three times faster than adenosine 2′,3′-cyclic phosphate. 6. 6. The purified enzyme was found to be free of deoxyribonuclease and non-specific phosphodiesterase activity. 7. 7. A molecular weight of about 37 000 was estimated for the enzyme by comparative gel filtration experiments.

The blanching hormone of the prawn, Pandalus borealis, is pGlu-Leu-Asn-Phe-Ser-Pro-Gly-Trp-NH(2). Its structure was settled by a combination of mass spectrometry and Edman-dansyl analysis of a thermolysin fragment. Confirmation of the structure was obtained by chemical synthesis from amino acids. This neurosecreted hormone is active in picogram amounts when tested in shrimps.

Shrimp red pigment-concentrations hormone (RPCH), locust adipokinetic hormone (AKH), and locust Compound I all elevate hemolymph lipid in locusts and concentrate pigment in shrimp erythrophores. In addition, RPCH and AKH both elevate hemolymph carbohydrate in cockroaches. Material with comparable biological activity has been reported in many insects, but not in representatives of the order Hymenoptera. Distilled water head extracts of the honeybe, Apis , exhibited red pigment-concentrating activity in the shrimp Leander and hyperglycemic activity in the cockroach Periplaneta . Chemical characterization of the active substance in Apis extracts showed that like RPCH, AKH, and Compound II, it was heat stable, soluble in butanol and methanol, degraded by proteolytic enzymes, and localized in the cephalic neuroendocrine system. Similarly, like RPCH and Compound II, but unlike AKH, the Apis substance eluted at 1.2 V t during Sephadex G-25 gel filtration. The data thus provide the initial demonstration that the endocrine system of at least one hymenopteran contains a peptide that is chemically and biologically comparable to the RPCH/AKH/Compound II group of hormonally active peptides. Furthermore, the results support the hypothesis that such peptides may be commonly used as hormones in holometabolic insects. In addition, pure Compound II was shonw for the first time to be hyperglycemic in the cockroach.

The significance of the terminal residues of the red pigment-concentrating hormone (RPCH: Glu-Leu-Asn-Phe-Ser-Pro-Gly-Trp-NH2) for its blanching effect on crustacean chromatophores has been investigated. The chemical synthesis of the following small analogues, starting from the C-terminal amino acid are described: Ac-Trp-NH2, Boc-Gly-Trp-NH2, Ac-Gly-Trp-NH2, Gly-Trp-NH2, Ac-Pro-Gly-Trp-NH2, Glu-Trp-NH2, Glu-Pro-Gly-Trp-NH2, Ac-Pro-Gly and Glu-Pro-Gly-NH2. Assay of the biological activity of the various synthetic compounds in the shrimp Leander adspersus has established that only the C-terminal tryptophan residue is indispensable for the blanching effect of the hormone, although elongation of the chain length improves its potency.

The red pigment-concentrating hormone, purified from Pandalus borealis, as well as the chemically synthesized octapeptide, is effective in concentrating the pigments in both the erythrophores and the leukophores of natantians, when tested on living animals as well as on isolated chromatophores. The existence of a receptor substance for the red pigment-concentrating hormone has been demonstrated. This is extractable from the chromatophores and might be a protein. The use of the synthetic hormone for an affinity chromatographic procedure for the isolation and purification of the receptor substance is envisaged.