Molecular genetics of the peptidyl transferase center and the unusual Var1 protein in yeast mitochondrial ribosomes

Mitochondria possess their own ribosomes responsible for the synthesis of a small number of proteins encoded by the mitochondrial genome. In yeast, Saccharomyces cerevisiae, the two ribosomal RNAs and a single ribosomal protein, Var1, are products of mitochondrial genes, and the remaining approximately 80 ribosomal proteins are encoded in the nucleus. The mitochondrial translation system is dispensable in yeast, providing an excellent experimental model for the molecular genetic analysis of the fundamental properties of ribosomes in general as well as adaptations required for the specialized role of ribosomes in mitochondria. Recent studies of the peptidyl transferase center, one of the most highly conserved functional centers of the ribosome, and the Var1 protein, an unusual yet essential protein in the small ribosomal subunit, have provided new insight into conserved and divergent features of the mitochondrial ribosome.

[A study of insulin sensitivity and its related factors in patients with non-insulin dependent diabetes mellitus and impaired glucose tolerance]

In order to evaluate insulin sensitivity and its related factors in abnormal glucose tolerance, 572 cases of non-insulin dependent diabetes mellitus (NIDDM), 647 cases of impaired glucose tolerance (IGT) and 543 normal controls were studied. The results showed that fasting insulin levels (FIns) and the prevalence of hyperinsulinemia were higher in NIDDM than that in IGT and higher in IGT than that in normal controls (P < 0.01). Insulin sensitivity index (ISI) [-ln(FInx x fasting blood glucose)] ranked from high to low in the order of normal controls, IGT subjects, newly-diagnosed NIDDM patients and patients with known NIDDM (P < 0.01). In each group ISI was smaller in obese subjects or patients than in non-obese ones. Mono-factor analysis demonstrated that ISI in each group was negatively related to body mass index (BMI) and positively related to high density lipoprotein (HDL)-cholesterol. ISI in NIDDM and IGT group was negatively related to blood pressure. Multiple analysis showed that the ISI had significantly negative correlation with BMI and some correlation with blood pressure and blood lipids. In conclusion, the patients with abnormal glucose tolerance had hyperinsulinemia and insulin resistance. ISI was related to some risk factors of vascular diseases.

[The influence of perindopril on intrarenal RAS in experimental diabetic rats]

OBJECTIVE

To examine the effect of perindopril on the intrarenal renin angiotensin system (RAS) in diabetic rats.

METHODS

Diabetes of rats was induced by a single injection of STZ. The rats were treated with perindopril (1 mg.kg-1.d-1) and the controls were given insulin only. Plasma and intrarenal renin activity (PRA, TRA) and angiotensin I (PAT I, TATII) were measured by radioimmunoassay in the diabetic rats at 1, 3, 6 months. Message RNA (mRNA) expression of renal angiotensinogen (TATO) and TATII receptor (TATII R) was assessed by slot blot hybridization.

RESULTS

At 6 month, TATII levels in the control group were significantly decreased compared with those of normal controls (P < 0.05), and TATII levels in perindopril treated rats were decreased remarkedly compared with those of the control group (P < 0.01). TRA was not different among the three groups at 3 to 6 months (P > 0.05). In slot blot hybridization TATII R mRNA expression in the control group was markedly increased compared with that of perindopril treated and normal control groups (P < 0.05, P < 0.01). TATO mRNA expression was not different among the three groups (P > 0.05) during the experimental period.

CONCLUSION

The abnormalities of intrarenal RAS existed in STZ induced diabetic rats, including the decrement of TATII content and the enhancement of TATII R mRNA expression. Perindopril could further decrease the level of intrarenal TATII, and inhibit its receptor mRNA expression.

Engineering of DNA binding proteins into site-specific cutters: reactivity of Trp repressor-1,10-phenanthroline chimeras

Trp repressor (TrpR) can be converted into a site-specific nuclease by chemical modification of the cysteine mutants TrpR D46C or TrpR E49C with 5-iodoacetamido-1,10-phenanthroline (OP). In the presence of cupric ion and 3-mercaptopropionic acid, TrpR-regulated operators are cleaved. The properties of these semisynthetic scission reagents have been compared. The E49C construct cleaves efficiently at two sites within the operator and the D46C cleaves at multiple sites. Molecular modeling indicates that the reason for the focused reactivity of E49C is that the OP is rigidly oriented in the protein-DNA complexes whereas the OP can adopt several orientations in TrpR D46C. Mutations and reaction conditions that increase the affinity of the repressor enhance the scission efficiency which approaches 100% within the acrylamide matrix. TrpR E49C-OP smoothly cleaves the trpEDCBA operator in a plasmid in a reaction dependent on the corepressor L-tryptophan. In the absence of tryptophan, non-specific cleavage of the plasmid is observed under the same conditions. Therefore, tryptophan not only directs cleavage to a specific site but also blocks it at non-specific sites. The analysis of the cleavage pattern of the trpEDCBA operator provides strong evidence for the tandem binding model in which protein-protein interactions stabilize binding on the DNA. TrpR E49C-OP should serve as the basis for the engineering of a family of highly specific semisynthetic scission reagents.

[Prevalence and risk factors of hypertension and coronary heart disease in the subjects with abnormal glucose metabolism]

The prevalence and risk factors of hypertension and coronary heart disease (CHD) in subjects with abnormal glucose metabolism (AGM) were studied in a population of 29,960 in the Capital Iron and Steel Corporation. The results showed that the prevalences of hypertension and CHD were 37.37% and 9.32% in diabetes group and 29.88% and 6.25% in impaired glucose tolerance group respectively. Both aging and obesity were the risk factors for AGM, hypertension and CHD. Hyperglycemia and hyperlipidemia were related to the occurrence of hypertension and CHD. Our results indicate that the prevalence of CHD and hypertension is significantly increased in AGM subjects, and they have many other risk factors of cardiovascular disease.

[Effects of insulin and captopril on growth of glomerular mesangial cells in STZ-induced diabetic rats]

OBJECTIVE

To observe the effects of insulin and captopril on growth of mesangial cells and on production of interleukin-6 (IL-6) and tumor necrosis factor (TNF) in culture media of glomerular cells.

METHOD

Streptozocin induced diabetic rats (DM rats) were compared with normal wistar rats.

RESULTS

The CPM value of 3H-TdR incorporated into mesangial cells in DM rats was significantly higher than that in Wistar rats. When the culture media was added by 5 x 10(-4) U/ml, 5 x 10(-3) U/ml and 5 x 10(-1) U/ml of insulin, the CPM value incorporated into mesangial cells and the concentration of IL-6 in the culture media of both DM and wistar rats were significantly higher than those of the control (no insulin). When captopril (10(-6) mol/L, 10(-4) mol/L, 10(-3) mol/L) was added into the media in different concentration, the cpm value of 3H-TdR and the concentration of TNF in DM rats were significantly lower than those of the control (no captopril). But the CPM value of 3H-TdR in Wistar rats was lower than that in the control, which was only seen in the concentration of 10(-3)M captopril.

CONCLUSION

Ins could promote 3H-TdR in corporation and increase the production of IL-6, and captopril inhibited 3H-TdR in corporation and decrease the production of TNF.

Identification of the yeast nuclear gene for the mitochondrial homologue of bacterial ribosomal protein L16

An open reading frame encoding a member of the L16 family of ribosomal proteins is adjacent to the URA7 gene on the left arm of chromosome II in Saccharomyces cerevisiae. The predicted L16-like polypeptide is basic (pl 11.12), contains 232 amino acids (26.52 kDa) and has 36% amino acid sequence identity to E. coli L16. Immunoblot analysis with polyclonal antibodies to the L16-like polypeptide showed specific cross-reaction with a 22,000 Mr mitochondrial polypeptide that co-sediments with the large subunit of the mitochondrial ribosome in sucrose density gradients. The levels of the L16 mRNA and protein varied in response to carbon source. In [rho degree] cells lacking mitochondrial rRNA, the L16 mRNA accumulated at normal levels, but the protein was barely detectable, indicating RNA-dependent accumulation of the L16 protein. Gene disruption experiments demonstrated that the yeast mitochondrial L16 is an essential ribosomal protein in vivo.

[Epidemiology of adult diabetes mellitus in a population of Capital Iron and Steel Company in Beijing]

To prevent the development of DM in susceptible individuals, 29859 subjects, aged from 30 to 64 years, from 32 units of the Company were studied by using WHO protocal and diagnostic criteria. The results showed that the average prevalence of DM and IGT was 3.63% and 4.19% respectively, standardized by census 1990 in Beijing, and it was increased with age. No sex difference in the prevalence of DM was found, but the prevalence of IGT was higher in females (5.55%) than in males. The obesity, overweight, positive DM family history and giant baby history, as well as high daily intake of protein were closely related to the prevalence of the disease. Smoking was in effective.

Discrimination of envelope frequency in one spectral region in the presence of modulation in another

This paper examines how discrimination of envelope frequency in one spectral region is affected by the presence of either correlated or uncorrelated modulation in another spectral region. Envelope-frequency discrimination thresholds, delta fe's, for a 60-dB SPL two-tone complex centered at 2 kHz were measured in the presence or absence of an auxiliary two-tone complex at another frequency. When present, the auxiliary complex had either the same envelope as the standard signal or an envelope that was uncorrelated with both the standard and variable signal. The results show that listeners can take advantage of correlation between simultaneous envelopes in different frequency regions to improve discrimination of a small change in envelope frequency, whereas the presence of uncorrelated envelopes causes interference with discrimination. Except when the auxiliary complex and the signal are close together in frequency, the discrimination advantage afforded by the correlated auxiliaries appears to reflect across-channel envelope processing. The discrimination interference caused by the uncorrelated auxiliaries, on the other hand, may reflect primarily within-channel interaction such as peripheral masking, although a small amount of across-channel masking also is apparent.

Absorption of fluorescein given under the upper lid

BACKGROUND

The need for a more efficacious approach to administer topical ocular medications prompted the authors to consider applying conventional eye drops under the upper lid rather than beneath the lower lid. Preliminary observations on patients with glaucoma using a beta-blocker beneath the upper lid suggested a drop in intraocular pressure into the normal range in some previously refractory patients being treated with the same medications. To test this clinical observation, the authors observed if there were any physiologic differences in topical fluorescein absorption into the anterior chamber when given beneath the upper lid versus the lower lid.

METHODS

A 5-microliters drop of fluorescein solution was placed under the upper-lid fornix of one eye and under the lower-lid fornix of the other eye in human volunteers, and absorption into the anterior chamber was measured at hourly intervals, for a total of 3 hours.

RESULTS

Hotelling T2 multivariate analysis for all 3 hours demonstrates that upper-lid administration of fluorescein results in significantly higher absorption of fluorescein into the anterior chamber than does lower-lid administration (P = 0.0088; for hours 2 and 3, the statistical differences is even more dramatic: P < 0.0044).

CONCLUSION

Using conventional eye drops beneath the upper lid, the authors observed increased absorption of fluorescein into the anterior chamber when compared with lower-lid administration. Profuse tearing, especially by younger subjects, significantly and rapidly diminished anterior chamber absorption of fluorescein. It is reasonable to consider further clinical studies to test this new approach to drug delivery.

Ion formation processes in the afterpeak time regime of pulsed glow discharge plasmas

The formation of ions following the termination of power in a pulsed glow discharge ion source is investigated. The populations of ionized species containing sputtered atoms M(+), M 2 (1) :, and MAr(+) are observed to maximize after the termination of discharge power. Collisions involving sputtered atoms and metastable argon atoms, Penning and associative ionization, are considered to be responsible for the formation of ions in the discharge afterpeak time regime. The domination of these ion formation processes during the afterpeak time regime is supported by the results from investigations of discharge operating parameters, metastable argon atom quenching, and ion kinetic energy distributions.

Activated C3 (C3b) in the nephritic glomerulus

An autoradiographic technique was developed to assess in the nephritic glomerulus the relative amount of C3 which is in the activated form, C3b, compared with the inactivated form, iC3b. Frozen renal biopsy sections from children and young adults with glomerulonephritis were assessed for the C3b fraction of total C3, using a radiolabeled monoclonal anti-C3c. Grain counts with this antibody, before and after reacting the section with 0.0002% trypsin, gave the relative amounts of total C3 and C3b, respectively. C3b was found in all diseases studied. To explain its presence, glomerular C3b acceptors which would restrict C3b inactivation were sought by immunofluorescence studies. C3b acceptor candidates were: IgG in aggregated form, IgA as found in the IgA nephropathies and the C3/C5 convertase, C4b,2a,3b. In acute post-streptococcal glomerulonephritis and membranoproliferative glomerulonephritis type III, diseases in which these acceptors were lacking, it is postulated that the nephritis strain-associated protein and absence of membrane cofactor protein, respectively, may be responsible for C3b deposition. The phlogistic effect of C3b is mediated largely by one of its products, C5b-9. However, the C3b: total C3 ratio failed to correlate with indices of glomerular inflammation, probably in part because the ratio is not a measure of total glomerular C3b.

Feedback inhibition of fully unadenylylated glutamine synthetase from Salmonella typhimurium by glycine, alanine, and serine

Bacterial glutamine synthetase (GS; EC 6.3.1.2) was previously shown to be inhibited by nine end products of glutamine metabolism. Here we present four crystal structures of GS, complexed with the substrate Glu and with each of three feedback inhibitors. The GS of the present study is from Salmonella typhimurium, with Mn2+ ions bound, and is fully unadenylylated. From Fourier difference maps, we find that L-serine, L-alanine, and glycine bind at the site of the substrate L-glutamate. In our model, these four amino acids bind with the atoms they share in common (the "main chain" +NH3-CH-COO-) in the same positions. Thus on the basis of our x-ray work, glycine, alanine, and serine appear to inhibit GS-Mn by competing with the substrate glutamate for the active site.

Effect of morphine on uptake of immunoglobulin G complexes by mesangial cells and macrophages

Focal glomerular sclerosis is the predominant renal lesion in heroin addicts. We studied whether morphine, a metabolite of heroin, could directly affect the uptake of immunoglobulin G (IgG) complexes by cultured mesangial cells (MC) and macrophages (MP). Pre-incubation of morphine (10(-6) M) decreased uptake of IgG complexes [morphine, 66,577 +/- 6,248 vs. control, 95,735 +/- 5,227 counts.min-1 (cpm).mg protein-1; P < 0.02] by MC. Morphine (10(-4)-10(-6) M) also inhibited (P < 0.01) uptake of 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate-labeled low-density lipoprotein by MC. MP pretreated with morphine (10(-6) M) also showed significantly (P < 0.02) lower uptake of IgG complexes (control 94,959 +/- 4,980 vs. morphine, 58,360 +/- 11,608 cpm/mg protein). Binding studies carried out at 4 degrees C on MC and MP indicated that morphine did not modulate surface binding of IgG complexes. Naloxone, a morphine antagonist, also produced a rather decreased (P < 0.05) uptake of IgG complexes by both MP and MC and did not inhibit the effect of morphine on the uptake of IgG complexes. In vivo studies indicated that morphine-treated rats had a higher (P < 0.05) accumulation of aggregated human IgG complexes (125I-labeled ahIgG) in their glomeruli when compared with untreated rats (control rats, 256,929 +/- 40,008 cpm/g protein vs. experimental rats, 398,317 + 51,512 cpm/g). Increased accumulation of 125I-ahIgG in the glomeruli from morphine-treated rats may either be related to increased delivery of 125I-ahIgG into the mesangium or be a result of decreased drainage of 125I-ahIgG from the mesangium.(ABSTRACT TRUNCATED AT 250 WORDS)

Mesangial cell immune injury. Synthesis, origin, and role of eicosanoids

The synthesis, cell origin, and physiologic role of eicosanoids were investigated in a model of mesangial cell immune injury induced by a monoclonal antibody against the rat thymocyte antigen Thy 1.1 also expressed in rat mesangial cells. A single intravenous injection of the antibody resulted in enhanced glomerular synthesis of thromboxane (Tx)B2, leukotriene (LT)B4, and 12-hydroxyeicosatetraenoic acid (HETE), whereas that of PGE2 and PGF2 alpha was either unaltered or impaired. The enhanced eicosanoid synthesis was associated with decrements in glomerular filtration rate (GFR) and renal blood flow (RBF). Complement activation mediated both the increments in TxB2, LTB4, and 12-HETE and the decrements in GFR and RBF. The decrements in GFR were abolished by the TxA2 receptor antagonist SQ-29,548. Although both neutrophiles and Ia (+) leukocytes infiltrated glomeruli, glomerular LTB4 originated mainly from the latter. Platelets entirely accounted for the enhanced 12-HETE synthesis in isolated glomeruli and to a lesser extent for that of LTB4 and TxB2. Glomerular PGE2 and PGF2 alpha originated from mesangial cells as their impaired synthesis coincided with extensive mesangial cell lysis. The observations indicate that in mesangial cell immune injury vasoactive and proinflammatory eicosanoids originate from recruited or activated Ia (+) leukocytes and platelets and may exert paracrine effects on mesangial cells.

Soft filamentous woven polyester arterial prosthesis from China

Woven polyester arterial prostheses have traditionally been known for their tight construction and smooth surface which has limited their healing capacity and resulted in poor attachment of their internal and external capsules. A new woven prototype has recently been developed in the Peoples' Republic of China. Among its unique features are its high physical porosity, softness and flexibility. This study undertook a series of in vitro tests to characterize its structure and physical properties in comparison with four commercial polyester grafts of North American origin. In addition, an animal trial was completed in which the new prototype was implanted as an infrarenal aortic substitute in 20 dogs for periods ranging from 4 h to 12 month. The in vitro tests confirmed a unique lightweight, highly porous, satin weave construction. Because of its high water permeability, preclotting was necessary before implantation. Once preclotted and installed, no significant blood loss was observed, and 19 of the 20 grafts remained patent at the sacrifice. Rapid full-width healing was achieved with tightly bound capsules, and more extensive tissue ingrowth was observed. Further work is needed to evaluate its long-term durability as an arterial substitute.

The prevalence of subclinical hypothyroidism in adults with low-normal blood thyroxine levels

The purpose of this study was to determine whether subclinical hypothyroidism, defined as the state in which there is an elevation of thyrotropin blood level (TSH) with a low-normal blood thyroxine level (T4), can be found in clinically healthy subjects. We identified, by screening of adults in an ambulatory patient care facility, 67 persons with T4 at the lower range of normal (4.5-6.0 micrograms/dL) who were free of acute nonthyroidal illness and who were not on medications known to affect T4, other than long term thyroxine therapy. TSH was determined in all 67 persons, whose ages ranged from 25 to 87 years. Nineteen persons in this population had a history of thyroid disease and 48 did not. Elevation of TSH was found in 13 subjects (19%), seven of whom had a history of thyroid disease. The prevalence of TSH elevation was 50% in those with T4 of 4.5- less than 5.0 micrograms/dL, 26% in those with T4 of 5.0-5.5 micrograms/dL, and 8% in those with T4 of greater than 5.5-6.0 micrograms/dL (p less than 0.02). Three of these 13 patients had been on thyroxine therapy at the time of the survey, and their thyroxine doses were adjusted, whereas five others were started on thyroxine therapy subsequent to the survey. Treatment doses as low as 0.05 mg/day increased the T4 and returned the TSH to normal in six patients. In two of five patients who went untreated, there was a substantial fall in T4 and/or a rise in TSH.(ABSTRACT TRUNCATED AT 250 WORDS)

Refractive index measurement using a standard compensating method

The first three significant digits of a sample's refractive index are compensated by a standard, therefore a precise measurement, which is the same as the refractive index of the standard, can be obtained. The method only needs a thin sample.

Clinical analysis of 15,089 operations on the heart and great vessels: results from the People's Republic of China

Over a 28-year period, from November 1957 through November 1985, 15,089 patients underwent operations on the heart and great vessels at The Shanghai Chest Hospital. Herein we examine this experience, with particular attention to factors that affected mortality. Seven thousand two hundred eighty-one patients underwent procedures for mitral stenosis; 149 (2.0%) of these died. Two thousand one hundred thirty-three patients underwent closure of a patent ductus arteriosus; this procedure was associated with 9 deaths (0.4%), 5 of which were caused by massive hemorrhage. After 1964, over 98% of the procedures were accomplished with a locally-manufactured surgical stapler. This device allowed us to perform without any deaths a consecutive series of 1,838 patent ductus arteriosus closures from January 1970 to the end of our study. One thousand five hundred twnety-one patients underwent repair of a ventricular septal defect; 60 died, for a mortality rate of 3.9%. One thousand four hundred thirty-five patients had repair of an atrial septal defect; 13 died during or after operation, for a mortality rate of 0.9%. Higher mortality was observed in groups with severe pulmonary hypertension. Six hundred fifty-one patients were treated for pulmonary stenosis; 24 died, for an operative mortality of 3.7%. Five hundred eighty-five patients underwent total correction of tetralogy of Fallot; 100 died, for a mortality rate of 17.1%. Two hundred forty-seven patients with constrictive pericarditis underwent 250 pericardiectomies; 17 (6.9%) died during or after operation. Two hundred one patients had mitral or aortic valve insufficiency, or both. These patients underwent mitral, aortic, or double valve replacement; 30 died (14.9% mortality). One hundred eleven patients underwent aortic aneurysm resection; 24 died, for an operative mortality of 21.6%. This is 1 of the largest cardiovascular series ever reported from the People's Republic of China; therefore, it is a useful data base for study of cardiovascular surgical procedures and their results over a 3-decade period.

Normal free thyroxine in critical nonthyroidal illnesses measured by ultrafiltration of undiluted serum and equilibrium dialysis

Considerable controversy exists concerning the assessment of thyroidal state in critically ill patients with decreased serum T4 and T3 concentrations, in part because serum free T4 values are often low in such patients no matter what method of measurement is used. We developed an ultrafiltration method to measure free T4 and free T3 in undiluted serum and compared the results with those obtained using a standard equilibrium dialysis method to measure free T4 and T3. In 30 consecutive intensive care unit (ICU) patients, serum free T4 values were similar to or higher than those in 12 normal subjects by both methods in most patients and were clearly distinguishable from those in hypothyroid patients. The serum total T4 concentrations in these patients ranged from 12.9-131.3 nmol/L (mean, 68.2; normal mean, 115.8). Free T4 by equilibrium dialysis was highly correlated with free T4 by ultrafiltration in the ICU group (r = 0.91; P less than 0.001). Serum free T3 levels, however, whether measured by equilibrium dialysis or ultrafiltration, were decreased in the ICU patients, confirming other reports of lowered free T3 in critically ill clinically euthyroid patients. Our findings suggest that the use of equilibrium dialysis of undiluted serum or ultrafiltration to measure serum free T4 concentrations will distinguish euthyroid hypothyroxinemic ICU patients from those with hypothyroidism.

Amelioration of normothermic canine liver ischemia with prostacyclin

A model of hepatic ischemia was developed in dogs using a pump-driven splanchnic-to-jugular vein bypass during crossclamping of the portal triad. An LD50 was established with three hours of ischemia. PGI2 given for one hour before the ischemic insult ameliorated the ischemic injury and increased survival.

Prolongation of pig-to-dog renal xenograft survival by modification of the inflammatory mediator response

The pathogenesis of hyperacute renal rejection consists of a nonspecific effector cascade that invokes most of the components of a typical acute inflammatory response. Platelet-activating factor (PAF) represents the most recent and perhaps the most significant mediator and promoting agent of this phenomenon. These studies evaluated SRI 63-441, a novel, synthetic, and the most potent PAF receptor antagonist available, alone and in combination with other prostanoids, for their ability to influence this response and to prolong renal xenograft survival and function in a model of pig-to-dog heterotransplantation. Inhibition of PAF by SRI 63-441 alone, at the dosage and schedule used in these experiments, did not significantly prolong xenograft survival or function. However, the combination of SRI 63-441 with either prostacyclin (PGI2) or prostaglandin E1 (PGE1) infusion demonstrated significant synergism, and resulted in a 6-9-fold increase in kidney survival and a 3-20-fold increase in urine output. Neither PGI2 nor PGE1 infusions alone significantly influenced this xenograft model. Electromagnetic flow studies demonstrated significantly delayed diminution in renal artery blood flow in the combination-treated animals. Serial and end-stage histologic examination of kidneys receiving combination therapy demonstrated a delayed onset of the pathologic deterioration and an overall amelioration of the entire process. These studies demonstrate that significant abrogation of a rapid and violent form of hyperacute rejection can be achieved solely by the pharmacologic manipulation of the inflammatory mediator response.

Thyroid hormone levels in diabetic mothers and their neonates

Infants born to diabetic mothers have decreased activity of many metabolic pathways which might be regulated by thyroid hormone. Serum TSH, T4, T3, and reverse T3 levels were measured in 22 term infants of diabetic mothers and in 9 normal term babies at 2, 12, 24, and 72 hours of age, as well as in maternal and cord sera. T4 binding index and free T4 levels were measured in 11 diabetic mothers and their babies and 5 normal mothers and babies. Mean TSH levels did not differ between diabetic and normal mothers or their infants. Mean T4 of the diabetic mothers (9.6 micrograms/dl) was significantly (p less than 0.005) less than the mean T4 of the normal mothers (12.8 micrograms/dl). Mean T4 of neonatal specimens was lower in infants of diabetic mothers for each determination, but this difference achieved statistical significance at the 12-hour sample only (p less than 0.001). Mean serum T4 binding index was similar in the neonatal specimens at each time period studied. Mean T3 of diabetic mothers (149 ng/dl) was significantly (p less than 0.001) less than that of normal mothers (217 ng/dl). At each time interval, mean T3 concentration in infants of diabetic mothers was significantly lower than that of normal infants. Levels of reverse T3 were not significantly different between normal and diabetic mothers or their neonates. These data suggest that there is an effect of maternal diabetes on T3 secretion or conversion of T4 to the more active hormone, T3, in the fetus and early newborn.(ABSTRACT TRUNCATED AT 250 WORDS)

Variable thyrotropin response to thyrotropin-releasing hormone after small decreases in plasma free thyroid hormone concentrations in patients with nonthyroidal diseases

Although a normal serum thyrotropin (TSH) concentration is generally considered to be the most important finding to support the clinical impression of euthyroidism in patients with nonthyroidal diseases and decreased serum triiodothyronine (T(3)), the regulation of TSH secretion in sick patients has not been studied previously. Accordingly, we studied the regulation of TSH secretion in 23 patients with nonthyroidal diseases; 15 of the patients had decreased serum T(3). TSH regulation was studied by measuring the TSH response to injected thyrotropin-releasing hormone (TRH) before and after effecting a small decrease in serum thyroxine (T(4)) and/or T(3) concentrations by iodide treatment, 262 mg daily for 10 d. Iodide treatment significantly decreased (> 10%) the free T(4) index (FT(4)-I) and/or free T(3) index (FT(3)-I) in all patients. FT(4)-I values were correlated (0.611, P < 0.001), with free T(4) concentration determined by equilibrium dialysis. Despite decreased FT(4)-I and/or FT(3)-I after iodide treatment in all patients, the TSH response to TRH after iodide treatment was augmented in only 8 of 15 patients who had decreased serum T(3) (group 1) and in only 5 of 8 patients who had a normal serum T(3). Mean base-line TSH concentration was increased significantly (P < 0.05) from 0.9+/-0.1 to 1.5+/-0.3 muU/ml in group 1 only. Comparison of the mean TSH response to TRH showed that there was no significant difference between groups 1 and 2. Moreover, no significant difference in thyroidal parameters was observed between patients who had augmented TSH response to TRH after iodides and those who had either similar or decreased TSH response irrespective of the initial serum T(3). These studies show that an augmented TSH response to TRH in response to a small reduction in serum T(4) and T(3) concentration occurred in only 57% of the entire group of patients with nonthyroidal diseases and that the presence or absence of a normal TSH response to this stimulus did not seem to be related to the base-line serum T(3) concentration. Because an increase in serum TSH in response to decreased serum T(4) and T(3) did not occur in about one-half of patients with nonthyroidal diseases, normal serum TSH may not be a reliable index of the euthyroid state in these patients.