Spatially resolving valley quantum interference of a donor in silicon.

Electron and nuclear spins of donor ensembles in isotopically pure silicon experience a vacuum-like environment, giving them extraordinary coherence. However, in contrast to a real vacuum, electrons in silicon occupy quantum superpositions of valleys in momentum space. Addressable single-qubit and two-qubit operations in silicon require that qubits are placed near interfaces, modifying the valley degrees of freedom associated with these quantum superpositions and strongly influencing qubit relaxation and exchange processes. Yet to date, spectroscopic measurements have only probed wavefunctions indirectly, preventing direct experimental access to valley population, donor position and environment. Here we directly probe the probability density of single quantum states of individual subsurface donors, in real space and reciprocal space, using scanning tunnelling spectroscopy. We directly observe quantum mechanical valley interference patterns associated with linear superpositions of valleys in the donor ground state. The valley population is found to be within 5% of a bulk donor when 2.85 ± 0.45 nm from the interface, indicating that valley-perturbation-induced enhancement of spin relaxation will be negligible for depths greater than 3 nm. The observed valley interference will render two-qubit exchange gates sensitive to atomic-scale variations in positions of subsurface donors. Moreover, these results will also be of interest for emerging schemes proposing to encode information directly in valley polarization.

Nanoscale control of graphene electrodes.

Single layer graphene nano-gaps are fabricated by applying the method of feedback-controlled electroburning to notched ribbon devices, which are plasma etched from CVD grown graphene that is wet-transferred onto pre-patterned metal electrodes. Electrical and structural characterizations show that nanometer size gaps form at the center of the notch. We have processed a total number of 1079 devices using this method with a fabrication yield of 71%. Our results demonstrate precise control over the size and position of the nano-gaps, and open up the possibility of graphene electrodes for large-scale integrated molecular devices.

Integrated logic circuits using single-atom transistors.

Scaling down the size of computing circuits is about to reach the limitations imposed by the discrete atomic structure of matter. Reducing the power requirements and thereby dissipation of integrated circuits is also essential. New paradigms are needed to sustain the rate of progress that society has become used to. Single-atom transistors, SATs, cascaded in a circuit are proposed as a promising route that is compatible with existing technology. We demonstrate the use of quantum degrees of freedom to perform logic operations in a complementary-metal-oxide-semiconductor device. Each SAT performs multilevel logic by electrically addressing the electronic states of a dopant atom. A single electron transistor decodes the physical multivalued output into the conventional binary output. A robust scalable circuit of two concatenated full adders is reported, where by utilizing charge and quantum degrees of freedom, the functionality of the transistor is pushed far beyond that of a simple switch.

Progesterone receptor isoforms in the mammary gland of cats and dogs.

Progesterone exerts its effect by binding to specific progesterone receptors (PR) within the cell. In dogs and cats, no data are available on PR isoforms as found in other species. We therefore investigated the sequence of the PR gene and encoded protein in dogs and cats, the expression of PR isoforms in mammary tissue using Western blots and the presence of PR in mammary tissue using immunohistochemistry. Comparison of the amino acid sequence of the canine and feline PR with human PR revealed major differences in the PR-B-specific upstream segment (BUS). However, the essential activation function 3 (AF3) domain was intact in the cat but mutated in the dog. The DNA and ligand-binding domains were highly similar among the species. In cats with fibroadenomatous hyperplasia (FAH), high expression of PR mRNA together with growth hormone (GH), GH receptor (GHR) and IGF-I mRNA was found in comparison with feline mammary carcinomas. Immunohistochemical analysis showed strong nuclear as well as cytoplasmic staining for PR in FAH. Western blot analysis revealed expression of the PR-A and PR-B isoforms in the feline mammary gland. In canine mammary tissue, the most abundant PR staining was found in proliferative zones of the mammary gland. Western blot analyses showed mainly staining for PR-A with lower PR-B staining. It is concluded that in dogs and cats both PR isoforms are expressed. The role of mutations found in the canine PR-B is discussed.

Transcriptomic analysis by RNA sequencing characterises malignant progression of canine insulinoma from normal tissue to metastatic disease.

Insulinomas (INS) are the most common human and canine functioning pancreatic neuroendocrine tumours. The long-term prognosis for malignant INS is poor, because micrometastases are frequently missed during surgery. As human and canine malignant INS share clinical and histopathological features, dogs have been proposed as models for INS research. Using RNA-sequencing, we conducted a pilot study to better understand the underlying molecular mechanisms of canine INS. Normal canine pancreas and lymph node control tissues were compared with primary INS and INS-metastatic lymph nodes, revealing more than 3,000 genes differentially expressed in normal pancreas compared to primary INS. Only 164 genes were differentially expressed between primary INS and INS-metastatic lymph nodes. Hierarchical clustering analysis demonstrated similar genetic profiles in normal pancreas and early clinical stage primary INS, whereas late clinical stage primary INS resembled the genetic profile of INS-metastatic lymph nodes. These findings suggest that markers of malignant behaviour could be identified at the primary site of the disease. Finally, using the REACTOME pathways database, we revealed that an active collagen metabolism, extracellular matrix remodelling, beta-cell differentiation and non-beta-cell trans-differentiation might cause disease progression and hyperinsulinism in INS, identifying major pathways worthy of future research in this currently poorly controlled disease.

Sulfation preceding deiodination of iodothyronines in rat hepatocytes.

In man and animals iodothyronines are metabolized by deiodination and conjugation with glucuronic acid or sulfate. Until now these processes have been regarded as independent reactions. However, in the present study a close interaction of these pathways was observed in the hepatic metabolism of 3,3'-diiodothyronine and 3,3',5-triiodothyronine. Studies with rat hepatocytes and liver microsomes indicated that sulfation of the phenolic hydroxyl group facilitates the deiodination of these compounds.

Adenohypophyseal function in dogs with primary hypothyroidism and nonthyroidal illness.

BACKGROUND: A recent study of dogs with induced primary hypothyroidism (PH) demonstrated that thyroid hormone deficiency leads to loss of thyrotropin (TSH) hypersecretion, hypersomatotropism, hypoprolactinemia, and pituitary enlargement with large vacuolated "thyroid deficiency" cells that double-stained for growth hormone (GH) and TSH, indicative of transdifferentiation of somatotropes to thyrosomatropes. HYPOTHESIS: Similar functional changes in adenohypophyseal function occur in dogs with spontaneous PH as do in dogs with induced PH, but not in dogs with nonthyroidal illness (NTI). ANIMALS: Fourteen dogs with spontaneous PH and 13 dogs with NTI. METHODS: Adenohypophyseal function was investigated by combined intravenous administration of 4 hypophysiotropic releasing hormones (4RH test), followed by measurement of plasma concentrations of ACTH, GH, luteinizing hormone (LH), prolactin (PRL), and TSH. In the PH dogs this test was repeated after 4 and 12 weeks of thyroxine treatment. RESULTS: In 6 PH dogs, the basal TSH concentration was within the reference range. In the PH dogs, the TSH concentrations did not increase with the 4RH test. However, TSH concentrations increased significantly in the NTI dogs. Basal and stimulated GH and PRL concentrations indicated reversible hypersomatotropism and hyperprolactinemia in the PH dogs, but not in the NTI dogs. Basal and stimulated LH and ACTH concentrations did not differ between groups. CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with spontaneous PH hypersecrete GH but have little or no TSH hypersecretion. Development of hyperprolactinemia (and possible galactorrhea) in dogs with PH seems to occur only in sexually intact bitches. In this group of dogs with NTI, basal and stimulated plasma adenohypophyseal hormone concentrations were not altered.

cDNA microarray profiles of canine mammary tumour cell lines reveal deregulated pathways pertaining to their phenotype.

Mammary cancer is the most common type of cancer in female dogs with a lifetime risk of over 24% when dogs are not spayed. The elucidation of the complete canine genome opens new areas for development of cancer therapies. These should be tested first by in vitro models such as cell lines. However, to date, no canine mammary cell lines have been characterized by expression profiling. In this study, canine mammary tumour cell lines with histologically distinct primary tumours of origin were characterized using a newly developed canine cDNA microarray. Comparisons of gene expression profiles showed enrichment for distinct biological pathways and were related to biological properties of the cell lines such as growth rate and in vitro tumourigenicity. Additionally, gene expression profiles of cell lines also showed correspondence to their tumour of origin. Major differences were found in Wnt, cell cycle, cytokine/Rho-GTPase, alternative complement and integrin signalling pathways. Because these pathways show an overlap at the molecular level with those found in human breast cancer, the expression profiling of spontaneous canine mammary cancer may also function as a biological sieve to identify conserved gene expression or pathway profiles of evolutionary significance that are involved in tumourigenesis. These results are the basis for further characterization of canine mammary carcinomas and development of new therapies directed towards specific pathways. In addition these cell lines can be used to further investigate identified deregulated pathways and characterize until now unannotated genes.

Expression and mutation analysis of Tpit in the canine pituitary gland and corticotroph adenomas.

Pituitary-dependent hyperadrenocorticism (PDH) in dogs is caused by a pituitary corticotroph adenoma. Although PDH is a common disorder in dogs, little is known about the underlying pathogenesis. In the pituitary glands of humans and mice, the pro-opiomelanocortin (POMC)-expressing cell lineages, the corticotrophs and melanotrophs, have a specific marker in common, the T-box transcription factor Tpit (Tbx19), which is obligate for POMC expression. Tpit also regulates the late differentiation of the corticotrophs and melanotrophs, and therefore may contribute to the pathogenesis of the corticotroph adenomas. The aim of this study was to perform an expression and mutation analysis of Tpit in the normal canine pituitary and in corticotroph adenomas. The distribution of the Tpit protein in the pituitary gland was studied with immunohistochemistry and the expression of the gene with RT-PCR. The coding region of Tpit cDNA from 14 dogs with PDH was screened for mutations. Tpit was expressed in corticotroph and melanotroph cells of the normal and adenomatous canine pituitary, and remained present in non-adenomatous corticotrophs of pituitaries from PDH dogs. No tumor-specific mutation in the Tpit cDNA from the corticotroph adenomas was found. However, a missense polymorphism in the highly conserved DNA-binding domain, the T-box, was discovered in one dog. It is concluded that Tpit can be used as a reliable marker for the corticotroph and melanotroph cells in the canine pituitary tissue and that mutations in the Tpit gene are unlikely to play a major role in the pathogenesis of canine corticotroph adenomas.

Thyrotropin-releasing hormone-induced growth hormone secretion in dogs with primary hypothyroidism.

Primary hypothyroidism in dogs is associated with increased release of growth hormone (GH). In search for an explanation we investigated the effect of intravenous administration of thyrotropin-releasing hormone (TRH, 10 microg/kg body weight) on GH release in 10 dogs with primary hypothyroidism and 6 healthy control dogs. The hypothyroid dogs had a medical history and physical changes compatible with hypothyroidism and were included in the study on the basis of the following criteria: plasma thyroxine concentration < 2 nmol/l and plasma thyrotropin (TSH) concentration > 1 microg/l. In addition, (99m)TcO(4)(-) uptake during thyroid scintigraphy was low or absent. TRH administration caused plasma TSH concentrations to rise significantly in the control dogs, but not in the hypothyroid dogs. In the dogs with primary hypothyroidism, the mean basal plasma GH concentration was relatively high (2.3+/-0.5 microg/l) and increased significantly (P=0.001) 10 and 20 min after injection of TRH (to 11.9+/-3.5 and 9.8+/-2.7 microg/l, respectively). In the control dogs, the mean basal plasma GH concentration was 1.3+/-0.1 microg/l and did not increase significantly after TRH administration. We conclude that, in contrast to healthy control dogs, primary hypothyroid dogs respond to TRH administration with a significant increase in the plasma GH concentration, possibly as a result of transdifferentiation of somatotropic pituitary cells to thyrosomatotropes.

Functional and morphological changes in the adenohypophysis of dogs with induced primary hypothyroidism: loss of TSH hypersecretion, hypersomatotropism, hypoprolactinemia, and pituitary enlargement with transdifferentiation.

From case studies in humans it is known that primary hypothyroidism (PH) may be associated with morphological and functional changes of the pituitary. There is no insight into the time scale of these changes. In this study, seven beagle dogs were followed up for 3 years after the induction of primary hypothyroidism. Three of these dogs were followed up for another 1.5 years while receiving l-thyroxine. Adenohypophyseal function was investigated at 2-month intervals with the combined intravenous injection of CRH, GHRH, GnRH, and TRH, and measurement of the plasma concentrations of ACTH, GH, LH, PRL, and TSH. In addition, after 2 years of hypothyroidism a single TRH-stimulation test and a somatostatin test were performed, with measurements of the same pituitary hormones. Every 6 months the pituitary gland was visualized by computed tomography (CT). Induction of PH led to high plasma TSH concentrations for a few months, where after concentrations gradually declined to values no longer significantly different from pre-PH values. A blunted response to stimulation of TSH release preceded this decline. Basal plasma GH concentrations increased during PH and there was a paradoxical hyperresponsiveness to TRH stimulation. Basal GH concentrations remained elevated and returned only to low values during l-thyroxine treatment. Basal PRL concentrations decreased significantly during PH and normalized after several months of l-thyroxine treatment. The pituitary gland became enlarged in all dogs. Histomorphology and immunohistochemical studies in 4 dogs, after 3 years of PH, revealed thyrotroph hyperplasia, large vacuolated thyroid deficiency cells, and decreased numbers of mammotrophs. Several cells stained for both GH and TSH. In conclusion, with time PH led to a loss of the TSH response to low T4 concentrations, hypersecretion of GH, and hyposecretion of PRL. The enlarged pituitaries were characterized by thyrotroph hyperplasia, large vacuolated thyroid deficiency cells, and double-staining cells, which are indicative of transdifferentiation.

Use of a gonadotropin releasing hormone agonist implant as an alternative for surgical castration in male ferrets (Mustela putorius furo).

Surgical castration in ferrets has been implicated as an etiological factor in the development of hyperadrenocorticism in this species due to a castration-related increase in plasma gonadotropins. In search for a suitable alternative, the effect of treatment with the depot GnRH-agonist implant, deslorelin, on plasma testosterone concentrations and concurrent testes size, spermatogenesis, and the typical musky odor of intact male ferrets was investigated. Twenty-one male ferrets, equally divided into three groups, were either surgically castrated, received a slow release deslorelin implant or received a placebo implant. Plasma FSH and testosterone concentrations, testis size and spermatogenesis were all suppressed after the use of the deslorelin implant. The musky odor in the ferrets which had received a deslorelin implant was less compared to the ferrets which were either surgically castrated or had received a placebo implant. These results indicate that the deslorelin implant effectively prevents reproduction and the musky odor of intact male ferrets and is therefore considered a suitable alternative for surgical castration in these animals.

ACTH-independent hyperadrenocorticism due to food-dependent hypercortisolemia in a dog: a case report.

In addition to adrenocortical tumours, aberrant expression of functional hormone receptors in the adrenal cortex may cause adrenocorticotrophic hormone (ACTH)-independent hyperadrenocorticism. Here we report on a 6 year old Vizsla dog in which ACTH-independent hyperadrenocorticism was associated with meal-induced hypercortisolemia. Diagnosis was based on history, physical findings, biochemical changes, and elevation of the urinary corticoid/creatinine ratio (UCCR) on two consecutive days (11 and 8.3 x 10(-6), reference range <8.3 x 10(-6)). Basal plasma ACTH concentration was found by repeated measurements to be suppressed (<1 ng/L, reference range 5-85 ng/L) and administration of corticotrophin releasing hormone (CRH) resulted in a minor increase (to 6 ng/L), consistent with ACTH-independent hyperadrenocorticism. Ultrasonography and computed tomography revealed two uniformly enlarged adrenal glands. Magnetic resonance imaging of the pituitary area showed a non-enlarged, normally enhancing pituitary gland. Based on these results, expression of functional aberrant adrenocortical receptors was suspected and the possibility of food-dependent hyperadrenocorticism was explored. The UCCR on two separate occasions rose from 11 and 8 x 10(-6) before a meal to 25 and 23 x 10(-6) at 3 h after ingestion of a meal, respectively. There was a corresponding increase in plasma cortisol concentration (from 90 to 150 nmol/L), while plasma ACTH concentration remained low or undetectable. Consistent with the diagnostic criteria for food-dependent hyperadrenocorticism in humans, administration of octreotide completely prevented meal-induced hypercortisolemia. The dog was treated successfully with the cortisol-synthesis-inhibitor trilostane (2h before meal), and at 26 months after the final diagnosis the dog is still in good condition. The combination of (1) low plasma ACTH concentration in the absence of an adrenocortical tumour, (2) an increase of >100% in UCCR after ingestion of a meal, (3) prevention of the meal-induced increase in plasma cortisol concentration by octreotide, and (4) reversal of signs of hypercortisolism by administration of trilostane a few hours before the meal led to the diagnosis of food-dependent hyperadrenocorticism in this dog.

Androgen receptor CAG repeat polymorphisms in canine prostate cancer.

BACKGROUND: Relatively shorter lengths of the polymorphic polyglutamine repeat-1 of the androgen receptor (AR) have been associated with an increased risk of prostate cancer (PC) in humans. In the dog, there are 2 polymorphic CAG repeat (CAGr) regions. OBJECTIVE: To investigate the relationship of CAGr length of the canine AR-gene and the development of PC. ANIMALS: Thirty-two dogs with PC and 172 control dogs were used. METHODS: DNA was extracted from blood. Both CAG repeats were amplified by polymerase chain reaction (PCR) and PCR products were sequenced. RESULTS: In dogs with PC, CAG-1 repeat length was shorter (P = .001) by an increased proportion of 10 repeats (P = .011) and no 12 repeats (P = .0017) than in the control dogs. No significant changes were found in CAG-3 length distribution. CAG-1 and CAG-3 polymorphisms proved not to be in linkage disequilibrium. Breed difference in allelic distribution was found in the control group. Of the prostate-disease sensitive breeds, a high percentage (64.5%) of the shortest haplotype 10/11 was found in the Doberman, whereas Beagles and German Pointers had higher haplotype 12/11 (47.1 and 50%). Bernese Mountain dogs and Bouvier dogs both shared a high percentage of 11 CAG-1 repeats and 13 CAG-3 repeats. Differences in (combined) allelic distributions among breeds were not significant. CONCLUSIONS AND CLINICAL IMPORTANCE: In this preliminary study, short CAG-1 repeats in the AR-gene were associated with an increased risk of developing canine PC. Although breed-specific differences in allelic distribution of CAG-1 and CAG-3 repeats were found, these could not be related to PC risk.

Steroidogenic factor-1 inverse agonists as a treatment option for canine hypercortisolism: in vitro study.

Hypercortisolism is one of the most commonly diagnosed endocrinopathies in dogs, and new targeted medical treatment options are desirable. Steroidogenic factor-1 (SF-1), an orphan nuclear hormone receptor, is a key regulator of adrenal steroidogenesis, development, and growth. In pituitary-dependent hypercortisolism (PDH), high plasma ACTH concentrations increase the transcriptional activity of SF-1. In adrenal-dependent hypercortisolism, SF-1 expression is significantly greater in dogs with recurrence after adrenalectomy than in those without recurrence. Inhibition of SF-1 could therefore be an interesting treatment option in canine spontaneous hypercortisolism. We determined the effects of 3 SF-1 inverse agonists, compounds IsoQ A, #31, and #32, on cortisol production, on the messenger RNA (mRNA) expression of steroidogenic enzymes and SFs, and on cell viability, in primary adrenocortical cell cultures of 8 normal adrenal glands and of 3 cortisol-secreting adrenocortical tumors (ATs). To mimic PDH, the normal adrenocortical cell cultures were stimulated with ACTH. The results show that only compound #31 inhibited cortisol production and SF-1 target gene expression in non-ACTH-stimulated and ACTH-stimulated normal adrenocortical cells but did not affect cell viability. In the AT cell cultures, the effects of #31 on cortisol production and target gene expression were variable, possibly caused by a difference in the SF-1 mRNA expressions of the primary tumors. In conclusion, inhibition of SF-1 activity shows much promise as a future treatment for canine hypercortisolism.

Notch pathway inhibition targets chemoresistant insulinoma cancer stem cells.

Insulinomas (INS) are the most common neuroendocrine pancreatic tumours in humans and dogs. The long-term prognosis for malignant INS is still poor due to a low success rate of the current treatment modalities, particularly chemotherapy. A better understanding of the molecular processes underlying the development and progression of INS is required to develop novel targeted therapies. Cancer stem cells (CSCs) are thought to be critical for the engraftment and chemoresistance of many tumours, including INS. This study was aimed to characterise and target INS CSCs in order to develop novel targeted therapies. Highly invasive and tumourigenic human and canine INS CSC-like cells were successfully isolated. These cells expressed stem cell markers (OCT4, SOX9, SOX2, CD133 and CD34), exhibited greater resistance to 5-fluorouracil (5-FU) and demonstrated a more invasive and tumourigenic phenotype in vivo compared to bulk INS cells. Here, we demonstrated that Notch-signalling-related genes (NOTCH2 and HES1) were overexpressed in INS CSC-like cells. Protein analysis showed an active NOTCH2-HES1 signalling in INS cell lines, especially in cells resistant to 5-FU. Inhibition of the Notch pathway, using a gamma secretase inhibitor (GSI), enhanced the sensitivity of INS CSC-like cells to 5-FU. When used in combination GSI and 5-FU, the clonogenicity in vitro and the tumourigenicity in vivo of INS CSC-like cells were significantly reduced. These findings suggested that the combined strategy of Notch signalling inhibition and 5-FU synergistically attenuated enriched INS CSC populations, providing a rationale for future therapeutic exploitation.

Growth hormone mRNA in mammary gland tumors of dogs and cats.

We have shown recently that in the dog progestin administration results in mammary production of immunoreactive growth hormone (GH). At present we demonstrate the expression of the gene encoding GH in the mammary gland of dogs and cats using reverse-transcriptase PCR. GH mRNA was found in the great majority of normal mammary tissues as well as benign and malignant mammary tumors of the dog and was associated with the presence of immunoreactive GH in cryostat sections. The mammary PCR product proved to be identical to that of the pituitary. The highest expression levels were found after prolonged treatment with progestins. In carcinomas GH mRNA was also found in progesterone receptor-negative tissue samples, indicating that after malignant transformation GH gene expression may become progestin independent. GH mRNA was also present in mammary tissues of cats with progestin-induced fibroadenomatous changes. It is concluded that GH gene expression occurs in normal, hyperplastic, and neoplastic mammary tissue of the dog. The expression in normal tissue is stimulated by progestins and might mediate the progestin-stimulated development of canine mammary tumors. The demonstration of progestin-stimulated GH expression in mammary tissue of cats indicates that the phenomenon is more generalized among mammals.

Adenohypophyseal function in bitches treated with medroxyprogesterone acetate.

The aim of this study was to investigate the effects of treatment with medroxyprogesterone acetate (MPA) on canine adenohypophyseal function. Five Beagle bitches were treated with MPA (10mg/kg, every 4 weeks) and their adenohypophyseal function was assessed in a combined adenohypophyseal function test. Four hypophysiotropic hormones (CRH, GHRH, GnRH, and TRH) were administered before and 2, 5, 8, and 11 months after the start of MPA treatment, and blood samples for determination of the plasma concentrations of ACTH, cortisol, GH, IGF-1, LH, FSH, prolactin, alpha-MSH, and TSH were collected at -15, 0, 5, 10, 20, 30, and 45 min after suprapituitary stimulation. MPA successfully prevented the occurrence of estrus, ovulation, and a subsequent luteal phase. MPA treatment did not affect basal and GnRH-induced plasma LH concentrations. The basal plasma FSH concentration was significantly higher at 2 months after the start of MPA treatment than before or at 5, 8, and 11 months after the start of treatment. The maximal FSH increment and the AUC for FSH after suprapituitary stimulation were significantly higher before treatment than at 5, 8, and 11 months of MPA treatment. Differences in mean basal plasma GH concentrations before and during treatment were not significant, but MPA treatment resulted in significantly elevated basal plasma IGF-1 concentrations at 8 and 11 months. MPA treatment did not affect basal and stimulated plasma ACTH concentrations, with the exception of a decreased AUC for ACTH at 11 months. In contrast, the maximal cortisol increment and the AUC for cortisol after suprapituitary stimulation were significantly lower during MPA treatment than prior to treatment. MPA treatment did not affect basal plasma concentrations of prolactin, TSH, and alpha-MSH, with the exception of slightly increased basal plasma TSH concentrations at 8 months of treatment. MPA treatment did not affect TRH-induced plasma concentrations of prolactin and TSH. In conclusion, the effects of chronic MPA treatment on adenohypophyseal function included increased FSH secretion, unaffected LH secretion, activation of the mammary GH-induced IGF-I secretion, slightly activated TSH secretion, suppression of the hypothalamic-pituitary-adrenocortical axis, and unaffected secretion of prolactin and alpha-MSH.

Plasma oxytocin concentrations during late pregnancy and parturition in the dog.

While oxytocin is widely used in the treatment of dystocia in dogs, there is little information about its secretion before and during normal unassisted whelping. We therefore measured plasma oxytocin concentrations during late pregnancy and the expulsive stage of parturition. Blood samples were collected from eight dogs at 3-min intervals during a 42-min period between the 2nd and 14th day before whelping and during parturition after the birth of 1-3 pups. The litters consisted of 5-15 pups and the progression of the expulsive stage was linear and nearly parallel in the eight bitches. The overall mean (+/-S.D.) plasma oxytocin concentration during late pregnancy was 3.6+/-2.1pg/ml. Mean values in individual dogs ranged from 1.2 to 7.4 pg/ml, but the intra-animal variation was rather small. During the expulsive stage the overall mean (+/-S.D.) plasma oxytocin concentration was 12.9+/-13.9 pg/ml, with mean values in individual dogs ranging from 3.5 to 46 pg/ml. The mean area under the oxytocin curve for parturient dogs was significantly higher (P<0.05) than for pregnant dogs. During the expulsive stage, the peak plasma oxytocin level in individual dogs ranged between 10 and 117 pg/ml. In six of the eight dogs a pup was born during blood collection and in five of these animals the plasma oxytocin concentration increased temporarily during periods of abdominal straining and expulsion. However, straining efforts and expulsion were not consistently associated with a rise in the circulating oxytocin level. It is concluded that in the dog plasma oxytocin levels are higher and more variable during the expulsive stage of parturition than during late pregnancy. Interrelationships between the secretion pattern of oxytocin, the level of uterine contractility, and the progress of fetal expulsion in dogs need further exploration.

Assessment of thyroid function in dogs with low plasma thyroxine concentration.

BACKGROUND: Differentiation between hypothyroidism and nonthyroidal illness in dogs poses specific problems, because plasma total thyroxine (TT4) concentrations are often low in nonthyroidal illness, and plasma thyroid stimulating hormone (TSH) concentrations are frequently not high in primary hypothyroidism. HYPOTHESIS: The serum concentrations of the common basal biochemical variables (TT4, freeT4 [fT4], and TSH) overlap between dogs with hypothyroidism and dogs with nonthyroidal illness, but, with stimulation tests and quantitative measurement of thyroidal 99mTcO4(-) uptake, differentiation will be possible. ANIMALS: In 30 dogs with low plasma TT4 concentration, the final diagnosis was based upon histopathologic examination of thyroid tissue obtained by biopsy. Fourteen dogs had primary hypothyroidism, and 13 dogs had nonthyroidal illness. Two dogs had secondary hypothyroidism, and 1 dog had metastatic thyroid cancer. METHODS: The diagnostic value was assessed for (1) plasma concentrations of TT4, fT4, and TSH; (2) TSH-stimulation test; (3) plasma TSH concentration after stimulation with TSH-releasing hormone (TRH); (4) occurrence of thyroglobulin antibodies (TgAbs); and (5) thyroidal 99mTcO4(-) uptake. RESULTS: Plasma concentrations of TT4, fT4, TSH, and the hormone pairs TT4/TSH and fT4/TSH overlapped in the 2 groups, whereas, with TgAbs, there was 1 false-negative result. Results of the TSH- and TRH-stimulation tests did not meet earlier established diagnostic criteria, overlapped, or both. With a quantitative measurement of thyroidal 99mTcO4(-) uptake, there was no overlap between dogs with primary hypothyroidism and dogs with nonthyroidal illness. CONCLUSIONS AND CLINICAL IMPORTANCE: The results of this study confirm earlier observations that, in dogs, accurate biochemical diagnosis of primary hypothyroidism poses specific problems. Previous studies, in which the TSH-stimulation test was used as the "gold standard" for the diagnosis of hypothyroidism may have suffered from misclassification. Quantitative measurement of thyroidal 99mTcO- uptake has the highest discriminatory power with regard to the differentiation between primary hypothyroidism and nonthyroidal illness.