Chronic hyperandrogenemia and western-style diet beginning at puberty reduces fertility and increases metabolic dysfunction during pregnancy in young adult, female macaques.

STUDY QUESTION: What are the impacts of elevated testosterone (T) and an obesogenic western-style diet (WSD), either independently or together, on fertility and metabolic adaptations of pregnancy in primates? SUMMARY ANSWER: Testosterone increases the time to achieve pregnancy, while a WSD reduces overall fertility, and the combination of testosterone and WSD additionally impairs glucose tolerance and causes pregnancy loss. WHAT IS KNOWN ALREADY: Both hyperandrogenemia and obesity are hallmarks of polycystic ovary syndrome, which is a leading cause of infertility among women worldwide. Female macaques receiving T and WSD beginning at puberty show increased metabolic, ovarian and uterine dysfunction in the non-pregnant state by 3 years of treatment. STUDY DESIGN, SIZE, DURATION: The same cohort of female rhesus macaques continued treatments from the time of puberty (2.5 years) to 4 years, including this fertility trial. There were four groups (n = 9-10/group): controls (C), T-treated (T; average total serum level 1.35 ng/ml), WSD-treated, and combined T and WSD-treated (T + WSD) females. PARTICIPANTS/MATERIALS, SETTING, METHODS: Females, which were typically having menstrual cycles, were paired for 4 days with a proven male breeder following the late follicular rise in circulating estradiol (≥100 pg/ml). The presence of sperm in the reproductive tract was used to confirm mating. Animals went through up to three successive rounds of mating until they became pregnant, as confirmed by a rise in circulating mCG during the late luteal phase and ultrasound evidence of a gestational sac at Day 30 post-mating (GD30). Placental vascular parameters were also measured at GD30. Metabolic measurements consisted of fasting levels of blood glucose and insulin at approximately GD30, 60, 90 and 115, as well as an intravenous (iv) glucose tolerance test (GTT) at GD115. MAIN RESULTS AND THE ROLE OF CHANCE: While all animals in the C and T groups eventually became pregnant, T-treated females on average had a greater interval to achieve pregnancy (P < 0.05). However, only ~70% of animals in the WSD and T + WSD groups became pregnant (P < 0.004). One pregnancy in T + WSD group resulted in an anembryonic pregnancy which miscarried around GD60, while another T + WSD female conceived with a rare identical twin pregnancy which required cessation due to impending fetal loss at GD106. Thus, the number of viable fetuses was less in the T + WSD group, compared to C, T or WSD. Placental blood volume at GD30 was reduced in all treatments compared to the C group (P < 0.05). Maternal P4 levels were elevated in the WSD (P < 0.03) group and E2 levels were elevated in T + WSD animals (P < 0.05). An increase in serum A4 levels throughout gestation was observed in all groups (P < 0.03) except WSD (P = 0.3). All groups displayed increased insulin resistance with pregnancy, as measured from the ivGTT during pregnancy. However, only the T + WSD group had a significant increase in fasting glucose levels and glucose clearance during the GTT indicating a worsened glucose tolerance. WSD treatment decreased female fetuses third trimester weights, but there was an interaction between WSD and T to increase female fetal weight when normalized to maternal weight. LARGE SCALE DATA: N/A. LIMITATIONS REASONS FOR CAUTION: The small number of pregnancies in the WSD and T + WSD groups hampers the ability to make definitive conclusions on effects during gestation. Also, the high fertility rate in the controls indicates the cohort was at their breeding prime age, which may impair the ability to observe subtle fertility defects. The low number of fetuses used for male and female analysis requires additional studies. WIDER IMPLICATIONS OF THE FINDINGS: The current findings strongly suggest that both hyperandrogenemia and obesity have detrimental effects on fertility and gestation in primates, which may be directly relevant to women with polycystic ovary syndrome. STUDY FUNDING/COMPETING INTEREST(S): All ONPRC Cores and Units were supported by NIH Grant P51 OD011092 awarded to ONPRC. Research reported in this publication was supported by the Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD) of the National Institutes of Health (NIH) under Award Number P50HD071836 (to R.L.S.). The authors have no competing conflict of interests to disclose.

Chronic combined hyperandrogenemia and western-style diet in young female rhesus macaques causes greater metabolic impairments compared to either treatment alone.

STUDY QUESTION: Does developmental exposure to the combination of hyperandrogenemia and western-style diet (WSD) worsen adult metabolic function compared to either treatment alone? SUMMARY ANSWER: Young female rhesus macaques treated for 3 years, beginning at menarche, with combined testosterone (T) and WSD have increased weight gain and insulin resistance compared to controls and animals treated with either T or WSD alone. WHAT IS KNOWN ALREADY: Hyperandrogenemia is a well-established component of polycystic ovary syndrome (PCOS) and can be observed in peripubertal girls, indicating a potential pubertal onset of the disease. Obesity is often associated with hyperandrogenemia in peripubertal girls, and overweight girls appear to be at higher risk for the development of PCOS later in life. STUDY DESIGN, SIZE, DURATION: Juvenile (2.5- year old) female rhesus macaques were divided into four groups (n = 10/group): control animals receiving cholesterol implants and a control diet with 15% of calories derived from fat (C), animals receiving T implants (mean serum levels: 1.35 ± 0.01 ng/ml) and a control diet (T), animals receiving a cholesterol implant and a WSD with 36% of calories derived from fat (WSD) and animals receiving a T implant and a WSD (T + WSD). Animals were maintained on the treatments for 36 months and were 5.5 years old at study completion. PARTICIPANTS/MATERIALS, SETTING, METHODS: Metabolic testing consisted of body measurements including weight, dual-energy X-ray absorptiometry scans, activity monitoring, and glucose tolerance testing at zero months and at least once every 12 months for the remainder of the study. Indirect calorimetry and serum hormone assays were performed following 36 months of treatment. MAIN RESULTS AND THE ROLE OF CHANCE: Body weight and fat mass gain were significantly increased in T + WSD at 24 and 36 months of treatment compared to the other three groups. Log transformed fasting insulin and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) were significantly increased in T + WSD animals at 3 years of treatment compared to all other groups. T-treatment caused a greater rate of decline in activity after 18 months, while food intake and metabolic rate were largely unaffected by treatments. LIMITATIONS REASONS FOR CAUTION: Variability was present in the metabolic parameters measured; however, this is similar to the heterogeneity observed in human populations. WIDER IMPLICATIONS OF THE FINDINGS: Chronic hyperandrogenemia beginning at puberty may exacerbate metabolic dysfunction in women consuming a WSD and account for the increased rates of obesity and insulin resistance observed in PCOS patients. Counseling of female patient populations with elevated androgens about the potential benefit of consuming a lower fat diet could improve long-term metabolic health outcomes. STUDY FUNDING/COMPETING INTEREST(S): Eunice Kennedy Shriver National Institute of Child Health & Human Development P50HD071836 and Oregon National Primate Center Grant P51 OD011092. The authors have no competing conflict of interests to disclose.

Arcuate nucleus neuropeptide coexpression and connections to gonadotrophin-releasing hormone neurones in the female rhesus macaque.

The underlying hypothalamic neurocircuitry by which metabolism and feeding regulates reproductive function has been well-studied in the rodent; however, recent data have demonstrated significant neuroanatomical differences in the human brain. The present study had three objectives, centred on arcuate nucleus neuropeptides regulating feeding and reproduction: (i) to characterise coexpression patterns in the female nonhuman primate; (ii) to establish whether these neuronal populations make potential contacts with gonadotophin-releasing hormone (GnRH) neurones; and (iii) to determine whether these contacts differ between the low and high GnRH-releasing states of pre-puberty and adulthood, respectively. Female nonhuman primates have several coexpression patterns of hypothalamic neuropeptides that differ from those reported in rodents. Cocaine- and amphetamine-regulated transcript (CART) is not coexpressed with pro-opiomelanocortin but instead with neuropeptide Y (NPY). CART is also expressed in a subpopulation of kisspeptin cells in the nonhuman primate, similar to observations in humans but diverging from findings in rodents. Very few GnRH-expressing neurones received close appositions from double-labelled kisspeptin/CART fibres; however, both single-labelled kisspeptin and CART fibres were in frequent apposition with GnRH neurones, with no differences between prepubertal and adult animals. NPY/agouti-related peptide (AgRP) coexpressing fibres contacted significantly more GnRH neurones in prepubertal animals than adults, consistent with increased NPY and AgRP mRNA observed in prepubertal animals. The findings of the present study detail significant differences in arcuate nucleus neuropeptide coexpression in the monkey compared to the rodent and are consistent with the hypothesis that arcuate nucleus NPY/AgRP neurones play an inhibitory role in controlling GnRH neuronal regulation in the prepubertal primate.

Leptin is not the critical signal for kisspeptin or luteinising hormone restoration during exit from negative energy balance.

Low levels of the adipocyte hormone leptin are considered to be the key signal contributing to inhibited gonadotrophin-releasing hormone (GnRH) release and reproductive acyclicity during negative energy balance. Hypoleptinaemia-induced inhibition of GnRH may be initiated with upstream inhibition of the secretagogue kisspeptin (Kiss1) because GnRH neurones do not express leptin receptors. The present study aimed to determine whether eliminating the hypoleptinaemia associated with caloric restriction (CR), by restoring leptin to normal basal levels, could reverse the suppression of the reproductive neuroendocrine axis. Fifty percent CR resulted in significant suppression of anteroventral periventricular Kiss1 mRNA, arcuate nucleus (ARH) Kiss1 and neurokinin B (NKB) mRNA levels and serum luteinising hormone (LH). Restoring leptin to normal basal levels did not restore Kiss1 or NKB mRNA or LH levels. Surprisingly, leptin did not activate expression of phosphorylated signal-transducer and activator of transcription-3 in ARC Kiss1 neurones, indicating that these neurones may not relay leptin signalling to GnRH neurones. Previous work in fasting models showing restoration of LH used a pharmacological dose of leptin. Therefore, in a 48-h fast study, replacement of leptin to pharmacological levels was compared with replacement of leptin to normal basal levels. Maintaining leptin at normal basal levels during the fast did not prevent inhibition of LH. By contrast, pharmacological levels of leptin did maintain LH at control values. These results suggest that, although leptin may be a permissive signal for reproductive function, hypoleptinaemia is unlikely to be the critical signal responsible for ARC Kiss1 and LH inhibition during negative energy balance.

Influence of targets and assessment region size on perceived conservation priorities.

We used an existing conservation opportunity area (OA) data layer for four contiguous ecological subsections within the Ozark Highlands to quantitatively evaluate the influence of conservation targets and assessment region size on conservation priorities. OAs are natural and seminatural land-cover patches that are away from roads and away from patch edges. To evaluate the influence of targets, we assigned a priority score to each OA polygon for each of five different conservation targets, including land-cover patch size, landform representation, target vertebrate richness, target breeding bird richness, and target land cover. The top-scoring OAs for each target were added to an OA selection set for that target until 50% of the study area was chosen. These five OA selection sets were overlain to quantify overlap in priorities. Only 1.6% of the study area, or 2.1% of all OA polygons, was selected by all five targets. To evaluate the influence of assessment region size, we compared results of priority ranking of OAs relative to the entire study area against a merged set of priority rankings established separately relative to each of the four subsections within the study area. When high-priority OAs were added until 25% of the region was within the selection set for each of the five targets, the sets based on the whole study area versus each subsection evaluated separately overlapped from 45.4% to 81.9%. Thus, perceived priorities of conservation assessments are strongly influenced both by the targets that are evaluated and by the size of the assessment region.

Preparation of an iodinated radioligand.

Radioactive tracers are useful for receptor measurement and for radioimmunoassays because of the ease with which radioactive ligands are detected. Typical receptor measurement methods include whole tissue receptor assays, autoradiography, and cell and membrane binding assays. The isotopes most commonly used in receptor measurement studies are tritium, carbon-14, and iodine-125, with the choice of isotope most often based on the specific activity required and the sensitivity and type of detection system available. Its high specific activity and easy detection make I-125 ideal for labeling large peptides and proteins. While the short half-life (60 days) of iodine requires frequent replacement with freshly iodinated compounds, this is also an advantage, as unused portions of radioligand can be held for decay and disposed of as nonradioactive waste. This unit describes the iodination of proteins or peptides using the 125I-labeled Bolton Hunter reagent, a convenient, easy-to-use, nonoxidizing labeling reagent.

Neuropharmacological assessment of potential dopamine D4 receptor-selective radioligands.

Radiolabeled dopamine D4 receptor-selective agents ([3H]1-benzyl-4-[ N-(3-isopropoxy-2-pyridinyl)-N-methyl]-aminopiperidine maleate; [3 H]PNU-101958. and [125I]1-[4-iodobenzyl]-4-[ N-(3-isopropoxy-2-pyridinyl)-N-methyl]-aminopiperidine; [125I]RBI-257) were prepared and characterized. With D4.2- and D2L receptor-transfected cell membranes, [3H]PNU-101958 showed high dopamine D4 receptor affinity and selectivity, and potent inhibition by dopamine D4 receptor-selective compounds. However, its binding with rat brain homogenates showed little regional selectivity, and pharmacology inconsistent with selective dopamine D4 receptor labeling. Autoradiography indicated partial displacement of [3H]PNU-101958 by unlabeled dopamine D4 receptor ligands without regional selectivity, and lack of selective labeling with [125I]RBI-257. The results encourage further efforts to develop better dopamine D4 receptor-selective radioligands.

Lamellar granule biogenesis: a role for ceramide glucosyltransferase, lysosomal enzyme transport, and the Golgi.

Although lamellar granules are critical to the formation of the epidermal permeability barrier and are a known marker of late keratinocyte differentiation, very little is known about the physiologic regulators of lamellar granule assembly and extrusion. Ceramide glucosyltransferase (CGT), the enzyme responsible for the synthesis of lamellar granule glucosylceramides (GlcCer; the precursors of the stratum corneum ceramides), is localized to the Golgi apparatus in other cell types. We have found that CGT is induced during keratinocyte culture differentiation coincident with increased GlcCer content and the appearance of lamellar granules. In this study we show that the differentiation-related CGT induction is likely mediated at the transcriptional level. In addition, all-trans retinoic acid, a well-known inhibitor of keratinocyte differentiation, prevents the appearance of lamellar granules and decreases culture CGT activity and GlcCer content without affecting sphingomyelin or total lipid content, indicating a specific inhibition of this enzymatic pathway. These data show a direct relationship between CGT activity and epidermal differentiation, suggesting that regulation of CGT expression is a critical part of epidermal barrier generation. The differentiation dependence of CGT activity, the key role of this Golgi-localized enzyme in epidermal GlcCer synthesis, and our previous finding that ceramides are converted to GlcCer in the Golgi apparatus in keratinocyte cultures, strongly suggest a Golgi origin for lamellar granules. In contrast to CGT, the activity of the lysosomal enzymes acid lipase and glucocerebrosidase is less clearly related to epidermal differentiation and the appearance of lamellar granules, although both enzymes show striking colocalization and enrichment in a subcellular lamellar granule fraction derived from pig epidermis. Acid lipase activity in the lamellar granule fraction was found to contain primarily a small lysosomal form of the enzyme, whereas total acid lipase secreted by keratinocyte cultures was found to contain a mannose-6-phosphorylated large prelysosomal form as well as a small lysosomal form. That secreted acid lipase activity is derived from both prelysosomal and lysosomal compartments suggests there may be multiple pathways by which lysosomal enzymes are secreted from keratinocytes. The combined secretion of lipid and lysosomal enzymes from lamellar granules places these organelles in the category of "dual-function" specialized secretory vesicles described in certain other cell types. Electron microscopic images of lamellar granules show shapes consistent with cross-sections of tubules or buds from tubules in addition to vesicles. These images provide evidence for the involvement of trans-Golgi network tubules and/or buds in lamellar granule synthesis and secretion.

125I-Tyro-sauvagine: a novel high affinity radioligand for the pharmacological and biochemical study of human corticotropin-releasing factor 2 alpha receptors.

Corticotropin-releasing factor (CRF) receptors encoded by two distinct genes have recently been identified and termed CRF1 and CRF2. CRF and the non-mammalian-related peptide sauvagine bind to and activate CRF1 receptors with high affinity and equal potency. Although CRF is significantly weaker at the CRF2 receptor, sauvagine retains its high affinity interactions with this receptor subtype. We expressed the human CRF1 and CRF2 receptor subtypes in stable cell lines and characterized 125I-Tyr0-sauvagine, a high affinity radiolabel suitable for the pharmacological and functional profiles of these proteins. 125I-Tyr0-sauvagine has high affinity (200-400 PM) for CRF1 receptors and demonstrates a pharmacological profile identical to that of 125I-Tyr0-ovine CRF-labeled CRF1 receptors. 125I-Tyr0-sauvagine binding to human CRF2 alpha receptors is saturable and of high affinity (KD = 100-300 PM) and demonstrates guanine nucleotide sensitivity typical of agonist binding to receptors. The pharmacological profile of 125I-Tyr0-sauvagine binding to CRF2 alpha receptors with respect to inhibition by CRF-related analogs is similar to the agonist profile of potencies obtained by measurements of cAMP production stimulated by these analogs in CRF2 alpha expressing cell lines and distinct from the profile of the CRF1 receptor subtype. Thus, the related nonmammalian peptides sauvagine and urotensin have high affinity and rat/ human CRF and ovine CRF have lower affinity for CRF2 receptors labeled with 125I-Tyr0-sauvagine. Because the distribution of CRF1 and CRF2 alpha receptors has been demonstrated to be distinct, suggesting selective functional roles for each receptor subtype, the ability to label CRF2 alpha receptors with 125I-Tyr0-sauvagine in vitro represents a unique opportunity for the discovery of subtype-selective nonpeptide ligands, which would presumably target different aspects of CRF-mediated disorders. We have thus identified and characterized a novel high affinity radioligand for the labeling of CRF2 receptors.

Absence of parvovirus B19 infection in chronic fatigue syndrome.

OBJECTIVE: To evaluate the presence of infection with parvovirus B19 in patients with chronic fatigue syndrome (CFS) who also had rheumatologic symptoms and mild hematologic abnormalities. METHODS: Seven patients meeting the Centers for Disease Control and Prevention working case definition for CFS who also had mild leukopenia, thrombocytopenia, or anemia were studied. Bone marrow was aspirated from each patient, and examined for morphologic abnormalities, including features seen in marrow infections with parvovirus B19, as well as for parvoviral DNA, using polymerase chain reaction (PCR) amplification. Serum obtained at the time of marrow aspiration was also evaluated for parvoviral DNA, using the PCR method, and was examined for the presence of IgM and IgG antibodies to the virus. RESULTS: No evidence of marrow involvement with parvovirus B19 was found in any patient. One patient had antibody evidence of a transient parvoviral infection, during which time an underlying thrombocytopenia worsened. CONCLUSION: Despite examining a selected group of patients thought most likely to have parvoviral infection, based on clinical and hematologic measures, no evidence of clinically important parvoviral infection was noted. Thus, it seems unlikely that parvovirus B19 plays a role in CFS, even though it has been associated with fibromyalgia, a clinically similar syndrome.

A carboxyl-terminally truncated mutant and nonglycosylated A2a adenosine receptors retain ligand binding.

The amino acids that comprise the ligand binding sites of adenosine receptors have not been identified. Adenosine and its agonist analogues differ from ligands for the well studied biogenic amine receptors and rhodopsin in that the adenosine receptor agonists are larger, contain a ribose moiety, and are uncharged at physiological pH. Thus, the locations of the ligand binding pockets of the adenosine receptors could differ significantly from those of the biogenic amine receptors. This report describes the characterization of a purification-amenable truncated mutant of the canine A2a adenosine receptor and demonstrates that neither the long carboxyl-terminal tail nor the glycosidic moiety appears to be required for ligand binding. The dog thyroid A2a adenosine receptor cDNA (RDC8) was subcloned into the mammalian expression vector pCMV4. A mutant A2a construct, in which six histidines replaced residues 310-412 as the carboxyl terminus of the protein, also was prepared. When overexpressed transiently in COS M6 cells, the wild-type and mutant A2a receptors exhibited similar 2-[p-(2-[3H]carboxyethyl)phenylethylamino]-5'-N- ethylcarboxamidoadenosine saturation binding and competition curve profiles. The following biochemical techniques confirmed that the COS M6 cells were transcribing and translating A2a receptors of the expected molecular masses: (a) immunoblotting with an antipeptide antibody directed against the putative carboxyl-terminal side of the second extracellular loop (Tyr155-Val172) of the canine A2a adenosine receptor, (b) photoaffinity labeling with the A2a-selective agonist 125I-2-[4-[2-[2-[(4-azidophenyl)methylcarbonylamino] ethylaminocarbonyl]ethyl]phenyl]ethylamino-5'-N-ethylcarboxamidoad enosine (125I-azido-PAPA-APEC), and (c) partial purification of the hexahistidine-tagged receptor on Ni2+.nitrilotriacetic acid resin. A presumed A2a receptor (44 kDa) from rabbit striatal membranes also was detected with the antisera against amino acids Tyr155-Val172 of the RDC8 receptor. Not only could the mutant A2a receptor be photolabeled specifically with 125I-azido-PAPA-APEC but so too could unglycosylated A2a receptors (i.e., from tunicamycin-treated COS M6 cells), either full length or truncated. In all of these cases, photolabeling was attenuated by both agonist and antagonist competitors.

125I-2-[4-[2-[2-[(4-azidophenyl)methylcarbonylamino] ethylaminocarbonyl]ethyl]phenyl] ethylamino-5'-N-ethylcarboxamidoadenosine labels transmembrane span V of the A2a adenosine receptor.

We have shown previously that 125I-2-[4-[2-[2-[(4-azidophenyl)methylcarbonylamino] ethylaminocarbonyl]ethyl]phenyl] ethylamino-5'-N-ethylcarboxamidoadenosine (125I-azido-PAPA-APEC) specifically and selectively photolabels RDC8 A2a adenosine receptors that have been overexpressed in COS M6 cells. Glycosylated, 125I-azido-PAPA-APEC-labeled, wild-type (412 residues; 45,031 Da) and carboxyl-terminally truncated (315 residues; 35,427 Da) receptors migrate with apparent molecular masses of > 40 and 31.5 kDa, respectively, whereas unglycosylated or deglycosylated wild-type and truncated A2a receptors migrate with apparent molecular masses of 40 and 28.5 kDa, respectively. Because nonspecific photoincorporation is not a complication, the present peptide mapping studies of the full length and truncated canine A2a adenosine receptors were carried out on unpurified COS M6 membrane preparations. After partial proteolysis it became clear that glycosylation increased the apparent molecular mass of either the wild-type or mutant A2a receptor by approximately 3 kDa. Although the A2a receptor was readily cleaved by a variety of chemical reagents and proteases, trypsin and endoproteinase Glu-C generated the most reproducible and, in the case of trypsin, the most complete fragmentation patterns. Radiolabeled peptides were identified by their apparent molecular masses, (in)abilities to be recognized by an antipeptide antibody to amino acids Tyr155-Val172 of the presumed second extracellular loop of the receptor, and (in)sensitivities to endoglycosidase F and tunicamycin treatments. A prominent, 7-kDa, radiolabeled peptide that was generated by trypsin digestion implicated putative alpha-helix V in the binding of 125I-azido-PAPA-APEC.

Parvovirus B19 infection in human immunodeficiency virus type 1-infected persons failing or intolerant to zidovudine therapy.

To determine the incidence of B19 infection in patients with AIDS who were being treated with dideoxyinosine, serial sera (n = 28) taken over a 2-year period from 14 individuals were analyzed with respect to anti-B19 serology and the presence of B19 DNA. All 14 individuals were anti-B19 IgM negative. Nine of 14 had B19 viremia by Southern analysis of polymerase chain reaction product. Five of 9 with B19 viremia had > or = 1 anti-B19 IgG-positive sample; none of 5 without viremia had anti-B19 IgG. Four of 9 viremic individuals had serially positive samples. All 4 had severe anemia (hemoglobin < 8.5 g/dL) while taking zidovudine. A fifth individual whose severe anemia resolved after zidovudine was discontinued did not have B19 viremia. Therefore, a significant proportion of this group of patients with AIDS who developed severe anemia while receiving zidovudine had persistent B19 infection. These results suggest that B19 infection should be considered in anemic patients with AIDS.

Introduction of a putative dopaminergic prodrug moiety into a 6,7-substitution pattern characteristic of certain 2-aminotetralin dopaminergic agonists.

On the basis of the premise that the dopaminergic agonist profile of 2-(di-n-propylamino)-5-hydroxy-6-methyltetralin (1a) is due to in vivo oxidation of the 6-methyl moiety and that 1a may represent a novel prodrug strategy, the vicinal methyl-hydroxyl substitution pattern was incorporated into the 6- and 7-positions of 2-(di-n-propylamino)tetralin to give the 6-methyl-7-hydroxy and 6-hydroxy-7-methyl isomers 8 and 9, respectively. A multistep synthetic approach was devised which permitted preparation of target molecules 8 and 9. Pharmacological data revealed that both target compounds exhibit modest dopamine-like effects in the cardioaccelerator nerve assay in the cat, but neither appeared to be metabolically activated as was the case with 1a. The effects of 9 (but not of 8) were antagonized by pretreatment with haloperidol. Thus, the 5-hydroxy-6-methyl substitution pattern in the 2-aminotetralins remains unique as a dopaminergic agonist prodrug structure.

Fragments of nasogastric tubes as esophageal foreign bodies in two horses.

Two horses were referred with fragments of nasogastric tubes as esophageal foreign bodies. Radiography and endoscopy were used to identify the location of the fragments. Portions of the tubes were retrieved by esophagotomy in 1 horse and by manual examination of the oral cavity in the other. Both tubes were friable in focal areas, but were quite pliable over most of the length of the tube.