Psychosocial and physical long-term outcome in patients with a history of takotsubo cardiomyopathy or myocardial infarction - a multi-centered case control study.

Physical long-term impacts of Takotsubo Cardiomyopathy (TTC) remain controversial and an underestimation of their severity becomes increasingly evident. Even less is known about mental long-term impacts of TTC. This study aims at a better understanding of the physical and mental long-term effects of TTC in comparison to myocardial infarctions (MI). On average 5 years after disease onset, 68 TTC patients and 68 age- and sex-matched MI patients were assessed for disease-related quality of life, depression, anxiety, chronic stress, social support, resilience, and life events prior to disease onset. Scores of TTC and MI patients were compared to each other and to normative references values. Regression analyses were used to evaluate the predictive value of the number of life events prior to disease onset for physical and mental long-term outcomes. Both groups displayed higher scores in depression and anxiety, higher levels of chronic stress, and lower scores in physical and mental quality of life in comparison to norm samples, while social support did not differ from norms. No differences between the two patient groups were observed. Within both groups, the majority of patients (TTC: 69.1%; MI: 60.3%) reported stressful life events prior to disease onset. In TTCs and MIs, the number of events had a significant impact on long-term mental health and chronic stress. Notably, both patient collectives scored higher in resilience than healthy controls. Results suggest negative long-term impacts of TTC on mental and physical wellbeing, comparable to those of MI. Besides a good somatic-medical care, psychotherapeutic support, including the development of functional coping strategies, might be warranted for TTC patients. The long-term impact of TTC should be taken as serious as that of MI.

In-vivo monitoring of acute DSS-Colitis using Colonoscopy, high resolution Ultrasound and bench-top Magnetic Resonance Imaging in Mice.

OBJECTIVE: The aim of this study was to establish and evaluate (colour Doppler-) high-resolution-ultrasound (hrUS) and bench-top magnetic resonance imaging (btMRI) as new methods to monitor experimental colitis. MATERIALS AND METHODS: hrUS, btMRI and endoscopy were performed in mice without colitis (n = 15), in mice with acute colitis (n = 14) and in mice with acute colitis and simultaneous treatment with infliximab (n = 19). RESULTS: Determination of colon wall thickness using hrUS (32 MHz) and measurement of the cross-sectional colonic areas by btMRI allowed discrimination between the treatment groups (mean a vs. b vs. c - btMRI: 922 vs. 2051 vs. 1472 pixel, hrUS: 0.26 vs. 0.45 vs. 0.31 mm). btMRI, endoscopy, hrUS and colour Doppler-hrUS correlated to histological scoring (p < 0.05), while endoscopy and btMRI correlated to post-mortem colon length (p < 0.05). CONCLUSIONS: The innovative in vivo techniques btMRI and hrUS are safe and technically feasible. They differentiate between distinct grades of colitis in an experimental setting, and correlate with established post-mortem parameters. In addition to endoscopic procedures, these techniques provide information regarding colon wall thickness and perfusion. Depending on the availability of these techniques, their application increases the value of in vivo monitoring in experimental acute colitis in small rodents. KEY POINTS: • Improved in vivo monitoring might balance interindividual differences in murine colitis. • In monitoring murine colitis, btMRI and hrUS are safe and technically feasible. • Very short examination times underline the usefulness especially of hrUS. • Results of btMRI and hrUS correlate with endoscopic and post-mortem findings.

Biofouling on polymeric heat exchanger surfaces with E. coli and native biofilms.

The biofouling affinity of different polymeric surfaces (polypropylene, polysulfone, polyethylene terephthalate, and polyether ether ketone) in comparison to stainless steel (SS) was studied for the model bacterium Escherichia coli K12 DSM 498 and native biofilms originating from Rhine water. The biofilm mass deposited on the polymer surfaces was minimized by several magnitudes compared to SS. The cell count and the accumulated biomass of E. coli on the polymer surfaces showed an opposing linear trend. The promising low biofilm formation on the polymers is attributed to the combination of inherent surface properties (roughness, surface energy and hydrophobicity) when compared to SS. The fouling characteristics of E. coli biofilms show good conformity with the more complex native biofilms investigated. The results can be utilized for the development of new polymer heat exchangers when using untreated river water as coolant or for other processes needing antifouling materials.

Lysosomal dysfunction causes neurodegeneration in mucolipidosis II 'knock-in' mice.

Mucolipidosis II is a neurometabolic lysosomal trafficking disorder of infancy caused by loss of mannose 6-phosphate targeting signals on lysosomal proteins, leading to lysosomal dysfunction and accumulation of non-degraded material. However, the identity of storage material and mechanisms of neurodegeneration in mucolipidosis II are unknown. We have generated 'knock-in' mice with a common mucolipidosis II patient mutation that show growth retardation, progressive brain atrophy, skeletal abnormalities, elevated lysosomal enzyme activities in serum, lysosomal storage in fibroblasts and brain and premature death, closely mimicking the mucolipidosis II disease in humans. The examination of affected mouse brains at different ages by immunohistochemistry, ultrastructural analysis, immunoblotting and mass spectrometric analyses of glycans and anionic lipids revealed that the expression and proteolytic processing of distinct lysosomal proteins such as α-l-fucosidase, ß-hexosaminidase, α-mannosidase or Niemann-Pick C2 protein are more significantly impacted by the loss of mannose 6-phosphate residues than enzymes reaching lysosomes independently of this targeting mechanism. As a consequence, fucosylated N-glycans, GM2 and GM3 gangliosides, cholesterol and bis(monoacylglycero)phosphate accumulate progressively in the brain of mucolipidosis II mice. Prominent astrogliosis and the accumulation of organelles and storage material in focally swollen axons were observed in the cerebellum and were accompanied by a loss of Purkinje cells. Moreover, an increased neuronal level of the microtubule-associated protein 1 light chain 3 and the formation of p62-positive neuronal aggregates indicate an impairment of constitutive autophagy in the mucolipidosis II brain. Our findings demonstrate the essential role of mannose 6-phosphate for selected lysosomal proteins to maintain the capability for degradation of sequestered components in lysosomes and autophagolysosomes and prevent neurodegeneration. These lysosomal proteins might be a potential target for a valid therapeutic approach for mucolipidosis II disease.

Beyond the tradition: test of an integrative conceptual model on nurse turnover.

AIM: This paper aimed to extend research on nurse turnover by developing and testing a theoretical model of turnover intention that includes two emergent key off-the-job constructs, work-family conflict (WFC) and community embeddedness (CE). BACKGROUND: Nurse turnover is considered one of the most significant issues in health care. There is a considerable body of knowledge that has focused on the study of the on-the-job factors of nurse turnover, showing the important role of job attitudes. Recently, WFC and job embeddedness (JE) have been identified as variables that could help explain levels of nurse turnover. METHODS: Using structural equation modelling from a cross-sectional survey, the relationships between the variables were explored in a sample of 440 nurses from an Italian public hospital. The questionnaire measures demographic data and psychosocial factors such as job satisfaction, organizational commitment, WFC, CE and turnover intentions. RESULTS: The findings supported the importance of non-work dimensions in turnover models. CONCLUSIONS: The results suggest that when studying turnover phenomena in health organizations, the extra-work domains (WFC and JE) can contribute to a decrease in the intention to leave, in addition to the more typically emphasized attitude dimension.

Washout of sevoflurane from the GE Avance and Amingo Carestation anesthetic machines.

BACKGROUND: Inhalational anesthetics must be removed from anesthetic machines to prevent malignant hyperthermia (MH) in susceptible patients or to treat MH occurring during inhalational general anesthesia. This study examines the sevoflurane washout from the GE Avance and Amingo Carestations™. METHODS: The care stations were contaminated with sevoflurane during general anesthesia. Then, the vaporizer was removed, the CO2 absorber was exchanged against an empty one and the breathing tubes were substituted by clean ones. In the first part, the fresh gas flow was 10 l/min. In the second part, the Advanced Breathing System™ (ABS™), the internal breathing circuit, was replaced by a laundered component. The fresh gas flow was set to 10 l/min for 10 min and to 5 l/min for the following 20 min. RESULTS: In the 25 measurements of the first part, the sevoflurane concentration decreased from a median of 31.60 ppm [interquartile range (IQR) 130.12 ppm] within 22 min in every case to values below 5 ppm and stayed there for the last 8 min of the measuring (P < 0.0001). In the 15 measurements of the second part, the sevoflurane concentration fell from the median of 8.56 ppm (IQR 8.99 ppm) within 5 min to values being significantly below 5 ppm and stayed there for the following 25 min (P < 0.0001). CONCLUSIONS: In case of sudden onset of MH, the Avance or Amingo Carestation™ can stay in place, if the fresh gas flow is increased to 10 l/min or more. To prepare these machines for MH-susceptible patients, the ABS™ should be substituted by a laundered component.

Eimeria tenella oocyst shedding and output in cecal or fecal contents following experimental challenge in broilers.

Two experiments were conducted to determine whether Eimeria tenella oocyst output in cecal and fecal contents, lesion development, and performance characteristics were affected by ad libitum versus restricted feeding and challenge level. In experiment 1, 144 Cobb 500 males were placed in battery cages with 6 chicks/pen. On d 20, half of the battery pens were placed on feed restriction and all broilers were orally challenged with Eimeria tenella oocysts at one of 3 challenge levels (0, 5,000, or 20,000 sporulated oocysts). Cecal and fecal material were collected separately from d 4 postchallenge through d 10 postchallenge for oocysts output (oocysts shed/g) determination. Six days postchallenge, 3 broilers from each pen were removed and subjected to necropsy for lesion assessment. In experiment 2, 96 Cobb 500 males were placed in identical battery pens with 8 chicks/pen. On d 14, restricted feeding was initiated and broilers were challenged with Eimeria tenella oocysts at one of 3 challenge levels (1,000, 5,000, or 20,000 oocysts). Twenty-four hour collections of cecal and fecal material were obtained separately from d 4 postchallenge through d 10 postchallenge for oocysts per gram and total output determination. Six days postchallenge, 4 broilers from each pen were removed and subjected to necropsy for lesion assessment. In both experiments, BW gain was not affected by challenge dose in either the ad libitum-fed or restrict-fed broilers. Increased lesion development was observed with increasing challenge levels, and oocyst shedding peaked between d 7 and 9 postchallenge in both experiments. Oocyst concentration was higher in cecal droppings compared with fecal material throughout peak shedding; however, total oocyst output for the challenge period was similar between fecal material and cecal droppings.

Immune response of broiler chickens fed different levels of arginine and vitamin E to a coccidiosis vaccine and Eimeria challenge.

One-day-old broiler chicks (n = 300) were orally vaccinated (Coccivac-B) and divided into 6 groups to evaluate Arg at 3 levels of supplementation, 0, 0.3, or 0.6% [normal level (NARG), medium level (MARG), or high level (HARG), respectively], and 2 levels of vitamin E (VE), 40 or 80 IU/kg of feed (VE40 or VE80, respectively), in a factorial experiment. Birds were reared in floor pens with fresh pine shavings and provided a corn-soybean-based diet and water ad libitum. At d 14, all chickens were orally challenged with a mixture of Eimeria field isolates (Eimeria acervulina, Eimeria maxima, and Eimeria tenella). In vitro heterophil and monocyte oxidative burst (HOB and MOB, respectively) was measured at d 21 from cells isolated from peripheral blood. Antibody levels (IgG, IgM, and IgA isotypes, ELISA) and NO were measured at d 14 and 28. The HOB was lower in birds fed the VE40 diets but was increased with the MARG and HARG treatments, whereas birds fed the VE80 diet had a higher HOB irrespective of Arg level. Birds fed the VE80 diet had high levels of MOB, which was not further improved by Arg, whereas birds fed the VE40-MARG diet had the highest MOB response. Plasma NO was not affected by diet at d 14, but at d 28, plasma NO was higher in birds fed the VE80-MARG or the VE40-NARG diet and lower in birds fed the VE80-NARG or the VE40-MARG diet. Birds fed the VE40-HARG or VE80-MARG diet had the highest IgG levels at d 14, but at d 28, birds fed the VE80-MARG diet had the highest IgG levels. The IgM concentration was lower in birds fed NARG levels irrespective of VE levels at d 14, but at d 28, IgM levels were higher in birds fed the VE40-HARG or the VE80-MARG feed. The IgA concentration was not consistently affected at d 14 or 28. These results suggest that Arg and VE fed at levels higher than those recommended by the NRC may play complementary roles on the innate and humoral immune response against an Eimeria challenge, potentially improving vaccine efficacy and response to field infections.

Use of Encapsulated Stem Cells to Overcome the Bottleneck of Cell Availability for Cell Therapy Approaches.

Nowadays cell-based therapy is rarely in clinical practice because of the limited availability of appropriate cells. To apply cells therapeutically, they must not cause any immune response wherefore mainly autologous cells have been used up to now. The amount of vital cells in patients is limited, and under certain circumstances in highly degenerated tissues no vital cells are left. Moreover, the extraction of these cells is connected with additional surgery; also the expansion in vitro is difficult. Other approaches avoid these problems by using allo-or even xenogenic cells. These cells are more stable concerning their therapeutic behavior and can be produced in stock. To prevent an immune response caused by these cells, cell encapsulation (e.g. with alginate) can be performed. Certain studies showed that encapsulated allo- and xenogenic cells achieve promising results in treatment of several diseases. For such cell therapy approaches, stem cells, particularly mesenchymal stem cells, are an interesting cell source. This review deals on the one hand with the use of encapsulated cells, especially stem cells, in cell therapy and on the other hand with bioreactor systems for the expansion and differentiation of mesenchymal stem cells in reproducible and sufficient amounts for potential clinical use.

Body weight and composition in laboratory rats: effects of diets with high or low protein concentrations.

Adult rats fed high concentrations of dietary protein for 9 weeks gained more weight than rats fed isoenergetic diets containing less protein. There were no significant differences in tail and body lengths among several groups of rats on diets containing different amounts of protein; however, total body fat was significantly greater in the rats fed on diets containing 25 percent protein compared to the rats fed 5 percent protein diets. These findings suggest that the role of dietary protein in obesity and other conditions deserves further scrutiny.

Glucagon-sensitive adenyl cylase in plasma membrane of hepatic parenchymal cells.

The plasma membrane of hepatic parenchymal cells contains an adenyl cyclase system that is stimulated by glucagon. Adrenocorticotropin and epinephrine do not stimulate this adenyl cyclase, and very little cyclic phospho-diesterase activity is present in the membrane. These findings support the concept that glucagon exerts its regulatory action in the liver by stimulating adenyl cyclase activity in the plasma membrane.

Observations on unaided smoking cessation after deep brain stimulation of the nucleus accumbens.

AIMS: We explore whether clinical research on deep brain stimulation (DBS) of the nucleus accumbens (NAc) to treat addiction is justified besides theoretical speculation. METHODS: Since 2004, 10 patients who were also smokers were treated at the University of Cologne for Tourette's syndrome (TS), obsessive-compulsive disorders (OCD) or anxiety disorders (AD) by DBS of the NAc. We assessed their smoking behavior after DBS and (in retrospection) before by the Fagerstrom Test for Nicotine Dependence (FTND) and additional items. RESULTS: Three male patients were able to quit smoking after DBS. They were less dependent and higher motivated compared to the rest of the sample. They are stimulated with a higher voltage. During 1-year, 2-year, and 30-month follow-ups, we found a higher rate of successful smoking cessation (20, 30 and 30%) compared to unaided smoking cessation in the general population (13, 19 and 8.7%). CONCLUSIONS: Albeit the results of the study are severely limited by the method of retrospective self-assessment of psychiatric patients, further research of DBS of the NAc to treat addiction seems justified. In addition to biological mediators, psychosocial factors should be assessed in further prospective studies.

Molecular analysis of the GlcNac-1-phosphotransferase.

Modification of the carbohydrate chains of soluble lysosomal enzymes with mannose 6-phosphate residues is a prerequisite for their mannose 6-phosphate receptor-dependent transport to lysosomes. GlcNac-1-phosphotransferase localized in the Golgi apparatus represents a hexameric alpha(2)beta(2)gamma(2) subunit complex and plays a key role in the formation of the mannose 6-phosphate recognition marker. Defects in the GlcNac-1-phosphotransferase complex cause two diseases, mucolipidosis type II and III, which are characterized by missorting and cellular loss of lysosomal enzymes, and lysosomal accumulation of storage material. The recent identification of two genes, GNPTAB and GNPTG, encoding the three subunits of GlcNac-1-phosphotransferase leads to an improvement of both pre- and postnatal diagnosis of affected individuals, and permits the analysis of structural requirements for efficient formation of mannose 6-phosphate residues on lysosomal enzymes. The alpha/beta subunits precursor matures by proteolytic cleavage and contains the catalytic activity as well as the capability to recognize lysosomal enzymes. The role of the gamma-subunits for activity, stability and oligomerization of the GlcNac-1-phosphotransferase subunits is still unclear.

Akkermansia muciniphila: a novel functional microbe with probiotic properties.

Akkermansia muciniphila is an intestinal anaerobe which has been proposed as a new functional microbe with probiotic properties. However, the species is not included in the European Union qualified presumption of safety (QPS) list and has not yet been assessed. Moreover, products containing A. muciniphila are not on the market and are thus controlled by the Novel Foods Regulation, which requires extensive safety assessment. This review addresses the safety aspects of the use of A. muciniphila based on published information on its functions in humans and predictions based on its activity in model animals. Further, comprehensive studies related to A. muciniphila and its safety properties have gradually appeared and are summarised here. Many of the criteria required for novel food safety assessment in Europe can thus be fulfilled. However, studies focusing on the toxicological properties of A. muciniphila, including long-term and reproduction studies, have not so far been reported and are discussed in the light of the observation that most, if not all, healthy subjects are known to carry this intestinal anaerobe. As this also applies to other beneficial bacteria found in the human intestinal tract, the A. muciniphila case can be seen as a model for the comprehensive safety evaluations required by the European authorities.

Trisomy 12 in chronic lymphoid leukemias--a metaphase and interphase cytogenetic analysis.

Trisomy 12 has been shown to be one of the most common chromosome abnormalities in chronic lymphoid leukemias of B-cell origin, and some studies suggested that it predicts poor overall survival. We have prospectively studied 42 patients with B-cell chronic lymphocytic leukemia (B-CLL) and three patients with B-prolymphocytic leukemia (B-PLL) for the incidence of trisomy 12 and other chromosome 12 aberrations applying fluorescence in situ hybridization (ISH) and conventional G-banding analysis. Dual-color hybridization experiments using centromere-12-specific DNA probes were performed for interphase cytogenetics. A subset of patients (n = 11) was analyzed using a DNA library for painting of chromosome 12. The incidence of trisomy/partial trisomy 12 was 18% (8/45 patients; 6/42 with B-CLL and 2/3 with B-PLL) by fluorescence ISH, and 11% (5/45 patients; 4/42 with B-CLL including one patient with partial trisomy 12q13-qter, and 1/3 with B-PLL) on G-banding analysis. Four patients with trisomy 12 were detected by ISH alone. One of these patients only had 4.5% interphase cells with three fluorescence signals indicating the presence of a small subclone with trisomy 12. On G-banding analysis, three of the four patients had a normal karyotype, and one patient had no analyzable metaphases. In conclusion, fluorescence ISH to interphase nuclei is a sensitive method for detecting trisomy 12 in patients with chronic lymphoid leukemias.

Evaluating clinical accuracy of systems for self-monitoring of blood glucose.

Although the scientific literature contains numerous reports of the statistical accuracy of systems for self-monitoring of blood glucose (SMBG), most of these studies determine accuracy in ways that may not be clinically useful. We have developed an error grid analysis (EGA), which describes the clinical accuracy of SMBG systems over the entire range of blood glucose values, taking into account 1) the absolute value of the system-generated glucose value, 2) the absolute value of the reference blood glucose value, 3) the relative difference between these two values, and 4) the clinical significance of this difference. The EGA of accuracy of five different reflectance meters (Eyetone, Dextrometer, Glucometer I, Glucometer II, Memory Glucometer II), a visually interpretable glucose reagent strip (Glucostix), and filter-paper spot glucose determinations is presented. In addition, reanalyses of a laboratory comparison of three reflectance meters (Accucheck II, Glucometer II, Glucoscan 9000) and of two previously published studies comparing the accuracy of five different reflectance meters with EGA is described. EGA provides the practitioner and the researcher with a clinically meaningful method for evaluating the accuracy of blood glucose values generated with various monitoring systems and for analyzing the clinical implications of previously published data.

Accuracy of perceiving blood glucose in IDDM.

Type I (insulin-dependent) diabetic individuals and health professionals often assume that the symptoms of extremely low or high blood glucose (BG) levels can be recognized and, consequently, appropriate treatment decisions can be based on symptom perception. Because no research has documented the validity of these assumptions, this study tested the ability to perceive BG concentration. Nineteen type I adults, experienced in self-monitoring of BG (SMBG), estimated their BG 40-54 times just before measurement of actual BG. This procedure was repeated under two conditions: (1) in the hospital (hospital condition) while connected to an insulin/glucose infusion system that artificially manipulated BG, leaving subjects only symptomatic, or internal, cues and (2) in the natural environment (home condition), where both internal and external cues, e.g., food and insulin consumption, were available. Estimates significantly correlated with actual BG for 7 of 16 subjects in the hospital condition and for 18 of 19 subjects in the home condition. Believed ability to estimate BG did not predict documented ability in either condition. An evaluation of the treatment significance of estimation errors showed that the majority of errors were relatively benign. The most common error affecting clinical outcome was estimated euglycemia when actual BG was hypoglycemic or hyperglycemic.

What Makes Umbilical Cord Tissue-Derived Mesenchymal Stromal Cells Superior Immunomodulators When Compared to Bone Marrow Derived Mesenchymal Stromal Cells?

MSCs derived from the umbilical cord tissue, termed UCX, were investigated for their immunomodulatory properties and compared to bone marrow-derived MSCs (BM-MSCs), the gold-standard in immunotherapy. Immunogenicity and immunosuppression were assessed by mixed lymphocyte reactions, suppression of lymphocyte proliferation and induction of regulatory T cells. Results showed that UCX were less immunogenic and showed higher immunosuppression activity than BM-MSCs. Further, UCX did not need prior activation or priming to exert their immunomodulatory effects. This was further corroborated in vivo in a model of acute inflammation. To elucidate the potency differences observed between UCX and BM-MSCs, gene expression related to immune modulation was analysed in both cell types. Several gene expression profile differences were found between UCX and BM-MSCs, namely decreased expression of HLA-DRA, HO-1, IGFBP1, 4 and 6, ILR1, IL6R and PTGES and increased expression of CD200, CD273, CD274, IL1B, IL-8, LIF and TGFB2. The latter were confirmed at the protein expression level. Overall, these results show that UCX seem to be naturally more potent immunosuppressors and less immunogenic than BM-MSCs. We propose that these differences may be due to increased levels of immunomodulatory surface proteins such as CD200, CD273, CD274 and cytokines such as IL1ß, IL-8, LIF and TGFß2.

Active hair growth (anagen) is associated with angiogenesis.

After the completion of skin development, angiogenesis, i.e., the growth of new capillaries from pre-existing blood vessels, is held to occur in the skin only under pathologic conditions. It has long been noted, however, that hair follicle cycling is associated with prominent changes in skin perfusion, that the epithelial hair bulbs of anagen follicles display angiogenic properties, and that the follicular dermal papilla can produce angiogenic factors. Despite these suggestive observations, no formal proof is as yet available for the concept that angiogenesis is a physiologic event that occurs all over the mature mammalian integument whenever hair follicles switch from resting (telogen) to active growth (anagen). This study uses quantitative histomorphometry and double-immunohistologic detection techniques for the demarcation of proliferating endothelial cells, to show that synchronized hair follicle cycling in adolescent C57BL/6 mice is associated with substantial angiogenesis, and that inhibiting angiogenesis in vivo by the intraperitoneal application of a fumagillin derivative retards experimentally induced anagen development in these mice. Thus, angiogenesis is a physiologic event in normal postnatal murine skin, apparently is dictated by the hair follicle, and appears to be required for normal anagen development. Anagen-associated angiogenesis offers an attractive model for identifying the physiologic controls of cutaneous angiogenesis, and an interesting system for screening the effects of potential antiangiogenic drugs in vivo.

Effects of thyroid hormones and thyrotropin-releasing hormone on thyrotropin biosynthesis by mouse pituitary tumor cells in vitro.

Mouse thyrotropic tumor cells grown in primary culture were shown to synthesize TSH and proteins, as determined by the incorporation of radioactive proline into immunoprecipitable TSH and trichloroacetic acid-precipitable proteins. The net TSH content of the cells and medium determined by RIA is also increased during 24 h of incubation, and newly formed hormone is detected in the medium within 1 h after the addition of proline tracer. To study the effect of T4 and T3 on TSH synthesis, cultures were pulse-labeled with [3H]proline after they had been exposed to either T3 or T4. After 48 but not 24 h, exposure to either T3 or T4 was followed by inhibition. When studied after 48 h of incubation, T4, (10(-13) M) or T3 (10(-11) M) at the lowest concentration tested, was inhibitory to TSH synthesis. At concentrations of T4 and T3 greater than 10(-9) M, the inhibitory effects on TSH synthesis were partially reversed, suggesting a biphasic response. Incubation in TRH (10(-7) M) for 24 h led to a significant increase in TSH synthesis, total protein, acid-precipitable protein, and total DNA. The effect of TRH on TSH biosynthesis was a function of the logarithm of its concentration over the range of 10(-11)-10(-7) M. The inhibitory action of 10(-6) M T3 on TSH synthesis was reversed by exposure to 10(-10) or 10(-7) M TRH.