Characterization Of The S' Subsite Specificity Of Trypsin

The S' subsite specificity of bovine trypsin has been studied by partitioning of o-nitrophenylsulfenyl-L-arginyl-trypsin (formed using o-nitrophenylsulfenyl-L-arginine alkyl esters as acyl donors) between various amino acid-derived nucleophiles and water. The data obtained from spectrophotometric measurements confirmed a preference of trypsin for arginine residues in the P'₁-position, which is less marked but quite similar to that of chymotrypsin. The amides of leucine, phenylalanine, methionine, threonine, lysine and valine are better for synthesis than the corresponding methyl esters, and show a moderate nucleophile efficiency, decreasing in that order. Amides of acidic amino acids and D-leucine were ineffective in forming the peptide bond, whereas norvaline amide and dipeptide amides lead to increased aminolysis.     

Evaluation Of Various Doses Of Recombinant Human Thyrotropin In Patients With Multinodular Goiters

ObjectiveTo assess the safety, adverse effects, and radioactive iodine uptake (RAIU) of recombinant human thyrotropin (rhTSH) using a range of doses in patients with multinodular goiters.MethodsIn this open-label study conducted between June 2002 and December 2004, euthyroid patients with small nontoxic multinodular goiters and normal thyrotropin concentrations were recruited from 4 sites in the United States. Baseline assessments included thyroid function tests, electrocardiogram, Holter monitoring, hyperthyroid symptom scale, flow-volume loop, and measurement of thyroglobulin and thyroperoxidase antibodies. Patients had a baseline 24-hour scan and thyroid iodine I 123 (¹²³I) uptake evaluated at 6, 24, and 48 hours after rhTSH administration. Each patient received a single intramuscular injection of 0.03-mg, 0.1-mg, or 0.3-mg rhTSH followed 24 hours later by 400 μCi ¹²³I orally. Iodine 123 uptakes were again measured 6, 24, and 48 hours later, and a scintigram scan was performed at 24 hours. Thyroid function tests, flow-volume loop, Holter monitoring and/or electrocardiograms, and thyroid ultrasonography to assess thyroid size were performed serially.ResultsTwenty-eight patients participated. Median goiter size was 20 mL (range, 7-79 mL). After each rhTSH dose, the radioiodine uptake approximately doubled at each time point compared with baseline uptake. Small rises in serum thyroxine and triiodothyronine were seen in some patients, especially after 0.3-mg rhTSH, and mild symptoms of hyperthyroidism developed in several patients. Flow-volume loop showed transient, mild asymptomatic worsening in 1 patient with a 35.2 mL goiter, although thyroid volume measurements were unchanged. Minor electrocardiogram and/or Holter changes were seen in several patients.ConclusionsA flat dose-response curve exists over the range of rhTSH doses tested, with an approximate doubling of thyroid RAIU. All patients tolerated rhTSH well, but the rise in thyroid hormone levels and adverse effects after rhTSH doses of 0.1 mg or higher theoretically might not be well tolerated in older or sicker patients and appear unjustified given the lack of a greater rise in RAIU compared with the 0.03-mg dose. Future studies evaluating rhTSH doses less than 0.1 mg in patients with multinodular goiter are justified. (Endocr Pract. 2008;14:832-839)     

Resolution Of Diabetes After Initiation Of Antiretroviral Therapy In Two Human Immunodeficiency Virus-Infected Patients

ObjectiveTo describe two cases of human immunodeficiency virus (HlV)-infected patients who had diabetes mellitus, which resolved after initiation of antiretroviral therapy.MethodsWe present the clinical and laboratory findings and describe the clinical course of these two patients.ResultsA 48-year-old HIV-infected black woman presented with multiple infections and hyperglycemia. After her acute infections were treated and she was feeling well, she continued to have diabetes that necessitated insulin therapy. Administration of a protease inhibitor-based antiretroviral regimen resolved her diabetes and eliminated the need for insulin or oral therapy. Our second patient, a 37-year-old HIV-infected black man, presented with polyuria and polydipsia and a hemoglobin A1c value of 11%. He received antiretroviral therapy, and his diabetes resolved after a period of 2½ months.ConclusionProtease inhibitor-based antiretroviral therapy is associated with diabetes mellitus in up to 6% of HIV-infected patients. Although most HIV-infected patients in whom diabetes develops have this disorder after initiation of protease inhibitor therapy, the current two cases illustrate patients in whom diabetes resolved after use of antiretroviral therapy. This finding supports the presence of other mechanisms that affect glucose metabolism in patients infected with HIV and suggests that control of HIV infection may have a role in controlling diabetes. (Endocr Pract. 2004;10:199-202)     

Hippocampal Homer1 Levels Influence Motivational Behavior in an Operant Conditioning Task

Loss of motivation and learning impairments are commonly accepted core symptoms of psychiatric disorders such as depression and schizophrenia. Reward-motivated learning is dependent on the hippocampal formation but the molecular mechanisms that lead to functional incentive motivation in this brain region are still largely unknown. Recent evidence implicates neurotransmission via metabotropic glutamate receptors and Homer1, their interaction partner in the postsynaptic density, in drug addiction and motivational learning. As previous reports mainly focused on the prefrontal cortex and the nucleus accumbens, we now investigated the role of hippocampal Homer1 in operant reward learning in the present study. We therefore tested either Homer1 knockout mice or mice that overexpress Homer1 in the hippocampus in an operant conditioning paradigm. Our results show that deletion of Homer1 leads to a diverging phenotype that either displays an inability to perform the task or outstanding hyperactivity in both learning and motivational sessions. Due to the apparent bimodal distribution of this phenotype, the overall effect of Homer1 deletion in this paradigm is not significantly altered. Overexpression of hippocampal Homer1 did not lead to a significantly altered learning performance in any stage of the testing paradigm, yet may subtly contribute to emerging motivational deficits. Our results indicate an involvement of Homer1-mediated signaling in the hippocampus in motivation-based learning tasks and encourage further investigations regarding the specific molecular underpinnings of the phenotypes observed in this study. We also suggest to cautiously interpret the results of this and other studies regarding the phenotype following Homer1 manipulations in animals, since their behavioral phenotype appears to be highly diverse. Future studies would benefit from larger group sizes that would allow splitting the experimental groups in responders and non-responders.     

Histochemical Demonstration Of Total Phosphorylase Activity For Diagnosis Of Carcinoma Cells In Human Stomach And Intestines

Modified techniques for the histochemical demonstration of phosphorylase of value in the diagnosis of cancer cells of human gastro-intestinal origin are described. Preservation of the enzyme activity is especially considered; this is facilitated by the use of thoroughly dried cryostat sections. Routine use of these techniques in the clinical laboratory is suggested. Using these procedures, carcinoma ceils of human stomach and intestines stained in 102 of 117 cases; normal control sections of human gastric epithelial cells are regularly unstained.     

Tactile Conditioning And Movement Analysis Of Antennal Sampling Strategies In Honey Bees (Apis mellifera L.)

Honey bees (Apis mellifera L.) are eusocial insects and well known for their complex division of labor and associative learning capability^{1, 2}. The worker bees spend the first half of their life inside the dark hive, where they are nursing the larvae or building the regular hexagonal combs for food (e.g. pollen or nectar) and brood³. The antennae are extraordinary multisensory feelers and play a pivotal role in various tactile mediated tasks⁴, including hive building⁵ and pattern recognition⁶. Later in life, each single bee leaves the hive to forage for food. Then a bee has to learn to discriminate profitable food sources, memorize their location, and communicate it to its nest mates⁷. Bees use different floral signals like colors or odors^{7, 8}, but also tactile cues from the petal surface⁹ to form multisensory memories of the food source. Under laboratory conditions, bees can be trained in an appetitive learning paradigm to discriminate tactile object features, such as edges or grooves with their antennae^{10, 11, 12, 13}. This learning paradigm is closely related to the classical olfactory conditioning of the proboscis extension response (PER) in harnessed bees¹⁴. The advantage of the tactile learning paradigm in the laboratory is the possibility of combining behavioral experiments on learning with various physiological measurements, including the analysis of the antennal movement pattern.