Analysis of adenovirus DNA detected in rodent species from the Democratic Republic of the Congo indicates potentially novel adenovirus types

Different species of adenoviruses (AdVs) infect humans and animals and are known for their role as pathogens, especially in humans, with animals, primarily rodents, often serving as model systems. However, although we know over 100 types of human AdVs, we know comparatively little about the diversity of animal AdVs. Due to the fact that rodents are the most diverse family of mammals and a standard model system for human disease, we set out to sample African rodents native to the Democratic Republic of the Congo and test them for AdV DNA using a semi-nested consensus PCR. A total of 775 animals were tested, and viral DNA was detected in four of them. The AdV DNA found belongs to three different AdVs, all being closely related to murine adenovirus 2 (MAdV-2). Considering the genetic differences of the amplicon were 9%, 11% and 19% from MAdV-2 and at least 10% from each other, they seem to belong to up to three different novel types within the Murine mastadenovirus B species. This evidence of genetic diversity highlights the opportunities to isolate and study additional AdVs that infect rodents as models for AdV biology and pathology.

Bunker probe: A plasma potential probe almost insensitive to its orientation with the magnetic field

Due to their ability to suppress a large part of the electron current and thus measuring directly the plasma potential, ion sensitive probes have begun to be widely tested and used in fusion devices. For these probes to work, almost perfect alignment with the total magnetic field is necessary. This condition cannot always be fulfilled due to the curvature of magnetic fields, complex magnetic structure, or magnetic field reconnection. In this perspective, we have developed a plasma potential probe (named Bunker probe) based on the principle of the ion sensitive probe but almost insensitive to its orientation with the total magnetic field. Therefore it can be used to measure the plasma potential inside fusion devices, especially in regions with complex magnetic field topology. Experimental results are presented and compared with Ball-Pen probe measurements taken under identical conditions. We have observed that the floating potential of the Bunker probe is indeed little affected by its orientation with the magnetic field for angles ranging from 90° to 30°, in contrast to the Ball-Pen probe whose floating potential decreases towards that of a Langmuir probe if not properly aligned with the magnetic field.

An analysis of spirochete load, strain, and pathology in a model of tick-transmitted Lyme borreliosis

Four laboratory-grown, low-passage isolates of Borrelia burgdorferi sensu stricto, B31, JD-1, 910255, and N40, were incorporated into Ixodes scapularis ticks to examine the pathogenesis of these isolates in mice after tick transmission. All isolates induced multifocal, lymphoid nodular cystitis, subacute, multifocal, necrotizing myocarditis, and a localized periostitis and arthritis of the femorotibial joint 6-18 weeks after tick infestation. In terms of the number of mice that demonstrated pathology in bladder, heart, and joint, the highest incidence of lesions occurred 12 weeks after tick bite. Utilizing the Taqman quantitative polymerase chain reaction (q-PCR) fluorogenic detection technology to amplify a conserved region of the flagellin gene, a trend was demonstrated between the number of spirochetes in tissue with duration of pathology. The q-PCR assay developed for this study was sensitive and could reliably measure as few as 1 to 10 spirochetes in the target tissues tested. A higher percentage of B31- and N40-infected mice (92 and 100%, respectively) developed myocarditis than JD-1- or 910255-infected mice (67 and 46%, respectively) 12 weeks after tick bite. The amount of spirochetal DNA that could be amplified for heart at this time point was not statistically different between isolates, indicating a difference in virulence between B31 and N40 relative to JD-1 and 910225. N40-infected mice demonstrated a significantly higher spirochete load (an average of 1.23 spirochetes/mg of tissue, p = 0.045) in femorotibial joints 18 weeks after infection, with 60% of these mice maintaining lesions compared with those infected with B31 (13%), JD-1 (25%), or 910255 (50%), which averaged <0.5 spirochetes/mg of tissue. This mouse model of Lyme borreliosis, including the ability to monitor lesion development and spirochete load, can facilitate the testing of therapeutic regimens for the later stages of tick-transmitted Lyme disease and help investigate aspects of the immunopathogenesis of lesion development.

Coinoculation of Borrelia spp. with tick salivary gland lysate enhances spirochete load in mice and is tick species-specific

C3H/HeN mice were inoculated with 10(6) spirochetes, either Borrelia burgdorferi strain N40 or the Portuguese strain of B. lusitaniae, PotiB2. Mice receiving spirochetes coinoculated with salivary gland lysate (SGL) demonstrated significantly higher spirochete loads in target organs as measured by quantitative real-time polymerase chain reaction. This effect was tick dependent, in that Ixodes ricinus SGL specifically enhanced B. lusitaniae load, whereas I. scapularis SGL specifically increased B. burgdorferi N40 load, but did not significantly affect the dissemination of B. lusitaniae. Protein profile analysis indicated at least 5 major protein differences between I. scapularis and I. ricinus SGL, which can possibly account for this specific tick-spirochete interaction.

Use of quantitative PCR to measure density of Borrelia burgdorferi in the midgut and salivary glands of feeding tick vectors

Quantitative real-time PCR was used to assay spirochetes in feeding ticks. Spirochetes in tick midguts increased sixfold, from 998 per tick before attachment to 5,884 at 48 h of attachment. Spirochetes in tick salivary glands increased >17-fold, from 1.2 per salivary gland pair before feeding to 20.8 at 72 h postattachment. The period of the most rapid increase in the number of spirochetes in the salivary glands occurred from 48 to 60 h postattachment; this time period coincides with the maximal increase in transmission risk during nymphal tick feeding.

Use of a sentinel host system to study the questing behavior of Ixodes spinipalpis and its role in the transmission of Borrelia bissettii, human granulocytic ehrlichiosis, and Babesia microti

Ixodes spinipalpis maintains Borrelia bissettii spirochetes in Colorado in a cycle involving wood rats and deer mice. This tick has been described as nidicolous, remaining either attached to its rodent hosts or in the rodent nest. Nidicolous ticks pose little risk of pathogen transmission to humans if they do not actively quest for hosts. To investigate the questing potential of I. spinipalpis, sentinel mice were placed in an area where I. spinipalpis had been commonly found on wood rats and deer mice. Concurrently, wild rodent populations were trapped and analyzed for Lyme disease spirochetes, the agent of human granulocytic ehrlichiosis (aoHGE), and Babesia microti. A total of 122 I. spinipalpis larvae and 10 nymphs were found on 19% of 244 sentinel mice. In addition, 4 sentinel mice became infested with Malaraeus telchinus or Orchopeas neotomae fleas. Questing I. spinipalpis were positively associated with woody shrubs and negatively associated with sunny and grassy areas. Four sentinel mice became infected with aoHGE after having been fed upon only by I. spinipalpis larvae. One sentinel mouse became infected with B. bissettii after having an I. spinipalpis nymph feed on it, and one sentinel mouse became coinfected with aoHGE and B. bissettii after it was fed upon by a single I. spinipalpis nymph. These sentinel mouse conversions suggest the possibility that the aoHGE is transovarially transmitted by I. spinipalpis, and that I. spinipalpis is capable of simultaneously transmitting B. bissettii and the aoHGE. The findings that I. spinipalpis quest away from rodent nests and will attach to and infect sentinel mice may be of public health importance. It suggests the potential transmission of the agents of human granulocytic ehrlichiosis and Lyme disease to other hosts by I. spinipalpis, in regions of the western United States where Ixodes pacificus is not found.

Consequences of skeletal muscle injury induced by unaccustomed exercise

Unaccustomed exercise is exercise that has never been performed before or has not been performed previously at a certain intensity. Unaccustomed exercise commonly leads to an acute skeletal muscle injury. Several negative consequences develop as a result of this injury and can interfere with daily and recreational physical activities. This article describes what the consequences are, when they occur and recover, and what might cause them to occur. Also, the article discusses the nursing implications of these consequences for healthy young and older individuals and for those individuals who have disuse muscle atrophy.

Borrelia lonestari DNA in adult Amblyomma americanum ticks, Alabama

Polymerase chain reaction analysis of 204 Amblyomma americanum and 28 A. maculatum ticks collected in August 1999 near the homes of patients with southern tick-associated rash illness and in control areas in Choctaw County, Alabama, showed Borrelia lonestari flagellin gene sequence from two adult A. americanum. The presence of B. lonestari in A. americanum ticks from Alabama suggests that this suspected pathogen may be widespread in the southeastern United States.

Babesia microti and Borrelia bissettii transmission by Ixodes spinipalpis ticks among prairie voles, Microtus ochrogaster, in Colorado

An endemic transmission cycle of Babesia microti was discovered in Colorado in the foothills of the Rocky Mountains. B. microti were found by PCR in 4 of 25 Ixodes spinipalpis tick pools tested (a 3.2 % minimum infection rate) and in 87% (13 of 15) of Microtus ochrogaster (the prairie vole) spleen and blood samples. Using naturally infected I. spinipalpis collected from wild-caught M. ochrogaster as vectors, B. microti and Borrelia bissettii were successfully transmitted to laboratory-born M. ochrogaster. Neither I. spinipalpis, nor M. ochrogaster (the prairie vole) have been previously reported as a vector or a reservoir host of B. microti. Unlike the east coast of the United States where Peromyscus leucopus is an important reservoir for B. microti, evidence for Peromyscus spp. (neither P. maniculatus nor P. difficilis) as B. microti reservoirs was not found in this study.

Retinal degeneration 6 (rd6): a new mouse model for human retinitis punctata albescens

PURPOSE

To characterize the genetics and phenotype of a new mouse mutant with retinal degeneration, rd6, that is associated with extensive, scattered, small white retinal dots seen ophthalmoscopically.

METHODS

The phenotype was characterized using ophthalmoscopy, fundus photography, electroretinography, light microscopy, immunocytochemistry, and electron microscopy. Genetic characterization and linkage analysis studies were performed using standard methods.

RESULTS

The inheritance pattern of rd6 is autosomal recessive. Linkage analysis mapped rd6 to mouse Chromosome 9 approximately 24 cM from the centromere, suggesting that the human homolog may be on chromosome 11q23. Ophthalmoscopic examination of mice homozygous for rd6 revealed discrete subretinal spots oriented in a regular pattern across the retina. The retinal spots appeared by 8 to 10 weeks of age and persisted through advanced stages of retinal degeneration. Histologic examination revealed large cells in the subretinal space, typically juxtaposed to the retinal pigment epithelium. The white dots seen on fundus examination corresponded both in distribution and size to these large cells. By 3 months of age, the cells were filled with membranous profiles, lipofuscin-like material, and pigment. These cells reacted strongly with an antibody directed against a mouse macrophage-associated antigen. Photoreceptor cells progressively degenerated with age, and an abnormal electroretinogram was initially detected between 1 and 2 months of age.

CONCLUSIONS

The fundi of mice homozygous for rd6 exhibit phenotypic similarities to the human flecked retinal disorder retinitis punctata albescens. Thus, rd6/rd6 mice may be a model for understanding the etiology of this or similar disorders. The relationship between the aberrant subretinal cells and the concomitant photoreceptor degeneration remains to be established.

Borrelia isolates in Northern Colorado identified as Borrelia bissettii

Previous work described Borrelia burgdorferi sensu lato group DN127 as a new genospecies, Borrelia bissettii, and prompted the present study to identify the Borrelia spp. that exist in northern Colorado. To determine the genospecies present, we analyzed two specific intergenic spacer regions located between the 5S and 23S and the 16S and 23S ribosomal genes. Phylogenetic analysis of the derived sequences clearly demonstrated that these isolates, originating from rodents captured in the foothills of northern Colorado, diverged from B. burgdorferi sensu stricto by 5 to 5.5% and were members of the new genospecies B. bissettii.

Transient headache and impaired vision after intravenous thyrotropin-releasing hormone in a patient with pituitary macroadenoma

We report a case of transient headache and impaired vision following administration of intravenous thyrotropin-releasing hormone (TRH) to a woman with a non-functioning pituitary macroadenoma, visual field defect, and elevated thyroid-stimulating hormone (TSH). The symptoms lasted for two hours and then resolved without known sequelae. There are a few other reported cases of similar adverse reactions to neuroendocrine manipulation in patients with pituitary macroadenomas. This is the second reported case of such adverse reactions to TRH alone and the first in which the patient had prior elevation of TSH.

Conducting biological research to advance rehabilitation nursing practice

Rehabilitation nursing practice is concerned with many clinical manifestations that have an underlying biological impairment. Advances in managing these manifestations will depend in part on research that incorporates the biological dimension. The purpose of this article is to encourage more rehabilitation nurses to engage in biological research. To achieve this aim, several different categories of biological nursing research are described using rehabilitation nursing examples, biological measures and approaches are discussed, and possible general clinical outcomes, with examples from previously published biological nursing research, are described. Biological nursing research may enhance professional competence, improve patient care, and improve patient safety.

Characterization of the unusual insulin of Psammomys obesus, a rodent with nutrition-induced NIDDM-like syndrome

Psammomys obesus fed a high-calorie diet develops a NIDDM-like syndrome. The use of reverse-phase high-performance liquid chromatography (HPLC) to study Psammomys insulin biosynthesis and release revealed a very delayed elution time for the Psammomys insulin peak appearing near the position of human proinsulin. This unusual peak was initially thought to represent partially processed insulin on the basis of its molecular size and susceptibility to trimming by carboxypeptidase B (CpB). However, the findings of an active carboxypeptidase E (CpE) enzyme and the normal amidated forms of gastrin and cholecystokinin octapeptide (CCK-8) in Psammomys tissues were inconsistent with CpE-related aberrant processing of insulin. Moreover, amino acid sequencing of the delayed peak of Psammomys insulin revealed fully processed insulin with amino acid sequence as predicted by the cDNA. The unique presence of a B-30 phenylalanine residue, resulting in an increased hydrophobicity of the insulin molecule, probably underlies the marked delay in elution time on HPLC. The unusual structure of Psammomys insulin does not appear to contribute to the proinsulinemia observed in diabetic Psammomys since the HPLC-purified molecule did not inhibit PC1 and PC2 convertase activities in an in vitro assay.

Statistical geometry of pancreatic islets

Quantitative histomorphometric studies of the dynamics of growth and development of pancreatic islets in normal and pathological states pose substantial methodological and conceptual problems. We address these problems with the geometry of random fractals, and apply our methods to the analysis of islet regeneration in the alloxan-treated guinea-pig. In both experimental islet-regenerated and control animals, islet centres are found to cluster in similar fractal subsets of dimension strictly less than 3, in agreement with the postulated origin of islets along a system of ductules, and suggesting that regeneration follows the same mathematical dynamics as original islet formation.

The spatial distribution of pancreatic islets follows a universal power law

In a previous report we quantified the apparently complex and irregular distribution of pancreatic islets in the guinea pig by showing that they formed a set of cluster or correlation dimension approximately 2.5. Here we show that this distribution holds in a wide range of mammalian species and through ontogenetic development in the guinea pig. These results strongly suggest that islet formation follows an iterative or fractal rule which is universal among mammals.

Lack of association of higher insulin levels with diffuse atherosclerotic coronary artery disease in nondiabetics

Since there is experimental evidence that insulin promotes atherosclerosis, we tested the hypothesis that insulin levels are higher in patients with diffuse atherosclerotic coronary artery disease by measuring insulin levels in 46 nondiabetic patients with angiographically defined diffuse coronary artery disease and 46 normal controls with angiographically normal coronary arteries. Fasting insulin levels were similar in both groups of patients: 7.70 +/- 5.77 microU/mL in those with diffuse coronary disease versus 7.39 +/- 5.01 microU/mL in controls. Also, insulin levels drawn 1 and 2 h after oral glucose challenge were not significantly different in patients with diffuse disease (48.78 +/- 32.46 microU/mL and 42.26 +/- 32.38 microU/mL, respectively) compared with patients with normal coronary arteries (51.03 +/- 28.01 microU/mL and 43.79 +/- 31.62 microU/mL, respectively). We conclude that insulin probably does not promote clinical atherosclerosis in nondiabetics.

Leukemia after a small dose of radioiodine for metastatic thyroid cancer

Radioiodine is widely used in the treatment of thyroid cancer. It is one of the most benign forms of therapy for malignancy. Leukemia is a rare complication of 131I therapy, usually occurring after cumulative dosages of more than 800 mCi and with intervals between doses of less than 12 months. We report the occurrence of acute myelogenous leukemia in a 28-yr-old woman 14 months after receiving a total dose of 300 mCi 131I for metastatic follicular thyroid cancer. We also review the published literature of the incidence of leukemia after low dose 131I.

Structure of a platinum(II) complex of levamisole

Chloro(ethylenediamine)[(-)-2,3,5,6-tetrahydro-6-phenylimidazo[2, 1-b]thiazole]platinum(II) chloride, [PtCl(C2H8N2)(C11H12N2S)]Cl, M(r) = 530.39, orthorhombic, P2(1)2(1)2(1), a = 31.676 (11), b = 8.190 (2), c = 6.6242 (6) A, V = 1718.5 (7) A3, Z = 4, Dx = 2.050 g cm-3, lambda (Mo K alpha) = 0.71069 A, mu = 86.8 cm-1, F(000) = 1016, T = 296 K, final R = 0.030 for 1646 unique observed reflections [F > 4 sigma (F)]. The Pt coordination is square planar, bonded to three N atoms (one from the levamisole and two from the ethylenediamine moiety) and to one Cl atom.

Tetracyclines inhibit intracellular muscle proteolysis in vitro

Tetracycline antibiotics (TETs) have a recently discovered novel action: inhibition of extracellular metalloproteinase activity, especially that of collagenase and gelatinase. This property, now confirmed in 8 different laboratories using > 40 tissue sources, includes natural and semi-synthetic TETs as well as a chemically modified TET (CMT) devoid of antimicrobial activity. We have used 14C-Tyr biosynthetically labelled intracellular proteins in L-6 myoblast culture as a test system to assess intracellular proteolysis. Starvation accelerates proteolysis, which can be suppressed by agents such as insulin or serum. Minocycline, doxycycline, and CMT all retarded the rate of intracellular protein degradation in a dose dependent manner. These agents also demonstrated marked synergism with insulin. A CMT derivative (pyrazole) stripped of one of its metal chelation sites and lacking anti-collagenase activity, also lost its antiproteolytic effect. CMT at physiologic concentrations (< or = 5 micrograms/ml) had no effect on protein synthesis, but at 15 micrograms/ml (pharmacologic), a suppressive effect was noted. These findings demonstrate that TETs can inhibit protein degradation as well as synthesis in a mammalian muscle-derived cell line.

Expression of the cholecystokinin gene in pediatric tumors

We have examined a wide range of cultured human tumor cell lines and found that a specific subset of tumors expresses the cholecystokinin (CCK) gene. All neuroepitheliomas (eight) and Ewing sarcoma (eight) cell lines that were tested express CCK RNA. In addition, two of six rhabdomyosarcoma cell lines also express the CCK gene, suggesting that rhabdomyosarcomas are probably heterogenous and that a subset may be similar to Ewing sarcoma and neuroepithelioma. Very few of the positive tumors express completely processed immunoreactive CCK. However, we have used a radioimmunoassay that detects the CCK precursor to demonstrate synthesis of CCK precursor-like peptides by all of the Ewing sarcoma and neuroepithelioma lines that were tested and by the rhabdomyosarcoma cell line that expresses CCK mRNA. These data demonstrate a consistent association of CCK gene expression with a specific group of human neoplasms. The data also add credence to the theory that Ewing sarcoma and neuroepithelioma are derived from the same transformed cell type. Finally, our results suggest that CCK gene expression may serve as a marker to distinguish these tumors, which are considered to be small-round-cell tumors of childhood, from other pediatric tumors.

Synthetic guinea pig insulin B-chain C-terminal decapeptide: a novel immunogen for generating immunocytochemical-grade antisera

Antisera to guinea pig insulin are not commonly available, largely because of the short supply and limited immunogenicity of the intact hormone. To overcome these problems we have employed a novel reagent, synthetic guinea pig insulin B-chain C-terminal decapeptide, as a hapten for raising antibodies that react with intact guinea pig insulin. The decapeptide, coupled to bovine serum albumin, was successfully used as an immunogen in rabbits. The resulting anti-serum was employed for immunocytochemical staining of guinea pig insulin in pancreatic sections. The specificity of the staining was verified by both pre-absorption and pre-immune serum controls. The utility of this new antiserum for investigations of guinea pig insulin physiology is discussed.

The course of lymphocytic hypophysitis

A 27-year-old woman presented to our institution in her seventh month of pregnancy with complaints of headache and visual field disturbance. Workup revealed bitemporal hemianopia, a markedly enlarged pituitary gland on computed tomography scan, and biochemical evidence of partial hypopituitarism. At surgery, a biopsy specimen of the pituitary gland was taken revealing lymphocytic hypophysitis. The patient was treated with steroids and replacement doses of thyroid hormone. Visual fields improved postoperatively. A repeat computed tomography scan obtained 2 months after an uneventful pregnancy showed that her pituitary had regained normal size and contour. Over the next 9 months she had gradual recovery of all pituitary function. This case allowed us to follow and document the course of lymphocytic hypophysitis from its presentation as a macroadenoma with partial hypopituitarism to full recovery of both size and hormonal function of the pituitary. Lymphocytic hypophysitis should be considered in the differential diagnosis of a pituitary mass or pituitary dysfunction presenting in pregnancy. In patients with suspected lymphocytic hypophysitis and a pituitary mass, a trial of steroids may be therapeutic.

Quantification and characterization of ACTH-related peptides produced by human peripheral blood mononuclear cells

We have used a sensitive radioimmunoassay to quantify and characterize PBMC-associated immunoreactive ACTH (ACTH-IR). Mean ACTH content of freshly isolated human PBMCs was 3.8 +/- 0.72 pg (SEM) per 10(6) cells. During 3 days of incubation ACTH-IR in conditioned media of control PBMCs increased significantly, p less than 0.02. Gel filtration chromatography revealed a minor peak of ACTH-IR coeluting with ACTH (1-39) and a major peak coeluting with ACTH (11-24). Treatment with 15 nM CRH did not alter the amount of ACTH-IR secreted or its gel pattern. Synthetic ACTH (11-24), was radioiodinated and was used for binding experiments that demonstrated specific high- and low-affinity binding sites for ACTH (11-24) on a human T cell line. These results add support for a role of ACTH and related peptides in immune regulatory systems and suggest that cell-specific post-translational processing of POMC may generate an expanding number of biologically active moieties.

Growth hormone response to growth hormone-releasing hormone in schizophrenic patients

Ten schizophrenic patients and five normal control subjects were challenged with growth hormone-releasing hormone in a pilot study investigating growth hormone secretion from the pituitary. The results suggest suprapituitary dysfunction in schizophrenia, but replication in a larger study is needed.

Studies of antiproteolytic effects of glyburide on rat L6 myoblasts: comparisons with insulin

Cultured L6 myoblasts afford considerable advantages for identifying and studying the insulin-like actions of test substances in a muscle-derived line. We have used this system to examine the interaction of the oral hypoglycemic sulfonylurea glyburide with bovine insulin on protein degradation and synthesis as well as on thymidine incorporation (as a measure of DNA synthesis) in these cells. Bovine insulin, at doses of 0.1 microgram/mL to 10 micrograms/mL, produced a dose-dependent inhibition of protein degradation (measured by release of trichloracetic acid (TCA)-soluble 14C-tyrosine from myoblasts into the culture medium) and increase in total protein content in the cultured myoblasts. At concentrations of 10 micrograms/mL, insulin achieved its maximal suppression of protein degradation (by nearly 50%) and increased cellular protein content (by 15%) over levels observed in the absence of added insulin. Glyburide, at concentrations at or above 1 microgram/mL, significantly suppressed protein degradation (up to 14%) and slightly augmented protein content of the cells. The effects of glyburide on protein degradation were additive with those of submaximally but not maximally effective concentrations of insulin, suggesting a common mechanism of action of the compounds. Both insulin and glyburide, at maximally effective doses, significantly depressed protein degradation as early as 2 to 6 hours after exposure. In addition, in a 24-hour labeling experiment, insulin stimulated tyrosine incorporation into TCA-insoluble protein and thymidine incorporation into DNA in the cells, whereas glyburide did not enhance these processes and, under certain conditions, inhibited them. These results demonstrate that glyburide, either alone or in concert with insulin, is capable of significantly inhibiting protein turnover in skeletal muscle-derived cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Level of expression and chromosome mapping of the mouse cholecystokinin gene: implications for murine models of genetic obesity

Cholecystokinin (CCK) is a neuropeptide which is present in brain and intestine and which stimulates gall bladder contraction and pancreatic secretion. Additional studies have demonstrated an appetite-suppressing effect of CCK in vivo. These data have aroused speculation that the physiology of this hormone could be relevant in the pathogenesis of the mouse obesity mutations ob on chromosome 6 and db on chromosome 4. In order to determine whether abnormalities of this hormone could be the primary defect in these obesity mutations, we have used three separate approaches to map the mouse Cck gene to distal chromosome 9, where it is part of a syntenic group between mouse chromosome 9 and human chromosome 3. These data therefore exclude cholecystokinin as the etiologic factor in the pathogenesis of any of the known mouse obesity syndromes. In order to exclude the possibility that there are differences in mutant animals in the level of CCK RNA, we have used an S1 nuclease protection assay as well as a novel radioimmunoassay that detects the CCK precursor, to show that there are no gross differences in CCK mRNA or protein precursor levels between ob/ob and wild-type animals.

Expression of the cholecystokinin gene by cultured human primitive neuroepithelioma cell lines

In this report we identify two cultured human primitive neuroepithelioma cell lines that express cholecystokinin (CCK) RNA and synthesize substantial amounts of pro-CCK, but differ in their ability to process the prohormone. Seven cultured human neural tumor lines, including two primitive neuroepitheliomas and five neuroblastomas, were screened for CCK gene expression using a CCK C-terminal RIA system, a RIA specific for the carboxy-terminal extension of prepro-CCK, and RNAse protection assays specific for CCK mRNA. RNA derived from the two primitive neuroepitheliomas yielded strong hybridization signals with CCK-specific probes. The five other neuronal tumors were negative for CCK mRNA. The two primitive neuroepitheliomas also synthesized substantial quantities of material reactive in the CCK carboxy-terminal extension RIA system. One of the tumors, Sk-N-Mc, postranslationally processed the CCK prohormonal material poorly, yielding only high mol wt CCK precursors and no immunoreactive CCK. The other, SK-PN-Dw, was able to process the prohormone, producing immunoreactive CCK-like material plus a peptide that immunochemically and chromatographically resembled the intact CCK C-terminal extension peptide. These cultured tumor lines should prove useful in furthering our understanding of the regulation of the CCK gene in human neuronal cells and will also provide an in vitro system for investigation of the posttranslational processing of the CCK preprohormone. In addition, the data demonstrate that screening procedures for examining peptide hormone expression by tumors are most comprehensive when specific molecular genetic probes are employed in addition to standard peptide assay methodology. Finally, these data suggest that CCK production may be a feature of some primitive neuroepitheliomas.

Development of Nelson's syndrome in a patient with recurrent Cushing's disease. Analysis of secretory behavior of the pituitary tumor

A markedly cushingoid 32-year-old man presented to Queens Hospital Center with headache, hyperpigmentation, and visual field loss. Twelve years earlier, he had undergone subtotal adrenalectomy for Cushing's disease, but symptoms of hypercortisolemia promptly recurred. Workup revealed the presence of a large, expanding intrasellar mass, plasma ACTH levels between 3,000 and 10,000 pg/ml, and markedly elevated cortisol levels. The secretion of ACTH (mainly ACTH 1-39-like peptide) by the pituitary tumor showed neither diurnal periodicity nor response to a variety of pharmacologic agents known to affect ACTH secretion. The patient demonstrates a rarely observed presentation of Nelson's syndrome, with aggressive adrenotropic pituitary tumor growth even in the presence of chronic hypercortisolemia.

Expression of a cholecystokinin precursor-related peptide in vertebrate and invertebrate tissues

We have developed a radioimmunoassay for the nonapeptide predicted by cDNA sequence analysis to reside at the extreme C-terminus of the mouse cholecystokinin (CCK) precursor. Sensitivity of the assay is 1 pg synthetic CCK precursor-related peptide (CCK-PRP)/ml. The antibody has no cross-reactivity with cholecystokinin, gastrin, or a variety of other known neuropeptides. We have employed this assay to demonstrate the presence, in rodent brain, gut, and peripheral plasma, of peptides with immunological properties that are identical to, and gel filtration characteristics that are very similar to, those of the synthetic CCK-PRP. We have also detected a similar peptide in the culture media of a human CCK-producing tumor. The molar ratios of immunoreactive CCK-PRP/CCK vary widely among tissues of origin and during ontogeny, suggesting regional and developmental differences in the turnover rates or in posttranslational modification of the two peptides. Our studies suggest that peptides very similar to intact CCK-PRP are posttranslationally liberated from the cholecystokinin precursor in a variety of tissues and may have neurotransmitter and/or hormonal functions distinct from those of CCK. Relatively high quantities of material immunologically indistinguishable from CCK-PRP were also found in several coelenterate species, indicating that this epitope arose as early in evolution as did CCK.

The regional and subcellular development of cholecystokinin immunoreactivity in vertebrate brain

We have previously demonstrated that the development of CCK in rat brain occurs during the first postnatal month. In order to determine whether the appearance of CCK is associated with specific aspects of brain histogenesis, we examined the development of brain CCK immunoreactivity in both precocial and altricial mammals and birds. The two precocial species (guinea pig and chicken) were found to achieve adult CCK concentrations prenatally, while the altricial species (zebra finch and rat) manifested adult brain CCK concentrations only after several weeks of postnatal development. In adulthood, both mammals showed relatively high forebrain CCK concentrations, while the two species of birds manifested much lower forebrain levels. Brainstem levels of CCK were similar in all species studied. In each species, the development of CCK followed a common time course across all major brain areas, although adult brainstem levels of CCK were generally attained shortly before adult forebrain levels. Correlation of our comparative ontogenetic data with known patterns of brain histogenesis indicated that CCK development follows regional neuroblastic proliferation, migration and differentiation, and occurs during or soon after local synaptogenesis. In the rapidly developing precocial chicken brain, CCK production precedes the postnatal gliogenic and myelinogenic increases in brain weight, suggesting that neurogenic production of CCK occurs independently of these non-neuronal maturation events. Subcellular fractionation of developing chicken brain revealed that a substantial fraction of brain CCK is localized in synaptosomes relatively early in embryogenesis; this synaptosomal localization becomes even more pronounced with further brain maturation. This early appearance of CCK in synaptic terminals indicates a correspondingly precocial maturation for the intraneuronal mechanisms subserving peptide cleavage, axonal transport and vesicular insertion, and suggests that CCK may be available for neurotransmission quite early in development. In an analysis of the molecular forms of CCK, gel filtration disclosed no differences between species or different brain areas in the form of CCK present. CCK-8 always predominated in brain, with smaller void volume (pro-CCK) peaks, and negligible amounts of CCK-33. Finally, duodenal CCK (largely CCK-33) appeared much earlier than brain CCK in all species examined, suggesting that the gut and brain CCK systems develop independently of one another.

Differential expression of the mouse cholecystokinin gene during brain and gut development

Cholecystokinin (CCK) is a neuropeptide found in brain and intestine. In this report, we have isolated a cDNA clone that encodes CCK from a mouse brain cDNA library. This cDNA clone has extensive homology to CCK precursors that have been sequenced previously. Southern blots of genomic DNA probed with this cDNA clone revealed single bands for each of eight different restriction enzymes, all of which could be accounted for by a single genomic clone, suggesting that the CCK gene is present as a single-copy gene in mice. RNA blots, primer extensions, and S1 nuclease protection assays have suggested that the same RNA start site is utilized in brain and in gut. Finally, we have shown, by using RNA blots and a radioimmunoassay specific for CCK, that CCK is expressed at maximum adult levels in intestine at birth but that adult concentrations of CCK and its mRNA are not reached in brain until much later in development.

Cholecystokinin antibody injected in cerebral ventricles stimulates feeding in sheep

The role of brain cholecystokinin peptides in satiety was further assessed by using antibody to cholecystokinin to reduce cholecystokinin activity in the cerebrospinal fluid of sheep. Food intakes were increased approximately 100 percent during the 2-hour continuous injection of antibody into the cerebrospinal fluid. This supports the hypothesis that, during feeding, cholecystokinin is released into the cerebrospinal fluid, which transports it to the receptors that elicit satiety.

Effects of altered adipose tissue morphology on plasma insulin levels in the rat

The usual covariates of adiposity--adipocyte size, total body fat, and food intake--were experimentally dissociated using three new models of altered adipose tissue morphology in the rat. It was thereby possible to test the hypothesis that plasma immunoreactive insulin level (IRI) is a function of mean adipocyte size. In two of the models, experimental and control rats differ substantially in total body fat but show no difference in mean adipocyte size. In these models, no difference in plasma IRI was found between experimental and control animals. In a third model, experimental and control rats differ in mean adipocyte size but not in total body fat or daily food intake. In this model, plasma IRI was found to differ between experimental and control rats. These observations demonstrate a close link between adipocyte size and plasma IRI and suggest that the hyperinsulinemia and peripheral insulin resistance of obesity are more likely due to adipocyte hypertrophy than to increases in total body fat or daily food intake.

Brain cholecystokinin and nutritional status in rats and mice

Under certain conditions, exogenously administered cholecystokinin (CCK) or its COOH-terminal octapeptide can terminate feeding and cause behavioral satiety in animals. Furthermore, high concentrations of CCK are normally found in the brains of vertebrate species. It has thus been hypothesized that brain CCK plays a role in the control of appetite. To explore this possibility, a COOH-terminal radioimmunoassay was used to measure concentrations of CCK in the cerebral cortex, hypothalamus, and brain stem of rats and mice after a variety of nutritional manipulations. CCK, mainly in the form of its COOH-terminal octapeptide, was found to appear in rat brain shortly before birth and to increase rapidly in cortex and brain stem throughout the first 5 wk of life. Severe early undernutrition had no effect on the normal pattern of CCK development in rat brain. Adult rats deprived of food for up to 72 h and rats made hyperphagic with highly palatable diets showed no alterations in brain CCK concentrations or distribution of molecular forms of CCK as determined by Sephadex gel filtration of brain extracts. Normal CCK concentrations were also found in the brains of four strains of genetically obese rodents and in the brains of six animals made hyperphagic and obese by surgical or chemical lesioning of the ventromedial hypothalamus. It is concluded that despite extreme variations in the nutritional status of rats and mice, CCK concentrations in major structures of the brain are maintained with remarkable constancy.