Reduction in hepatic triiodothyronine binding capacity induced by fasting.

Triiodothyronine (T3) receptor kinetics were determined in liver nuclei isolated from fasting and fed rats. The results indicate that although affinity equilibrium constants (Ka) did not differ in the two groups, mean (+/- SE) maximal binding capacity (MBC) was reduced significantly to .30 +/- .05 nM/mg DNA in fasting compared to .46 +/- .07 nM/mg DNA (p less than .01) in the fed state. This observed decrease in MBC during fasting apparently could not be accounted for by a differential rates of loss of either DNA or of the receptor during the period of incubation.

A radioimmunoassay for 3,3',5'-L-triiodothyronine (reverse T3): assessment of thyroid gland content and serum measurements in conditions of normal and altered thyroidal economy and following administration of thyrotropin releasing hormone (TRH) and thyrotropin (TSH).

The present report describes the development of a radioimmunoassay for 3,3',5'-L-triiodothyronine (reverse T3) which is performed on unextracted serum. Utilizing this radioimmunoassay, 21 normal subjects had a mean (+/-SD) serum reverse T3 level of 60 +/- 12 ng/100 ml, 17 of 19 hyperthyroid patients had elevated serum reverse T3 levels, and 10 of 11 hypothyroid subjects had decreased serum reverse T3 concentrations. Thyroidal secretion of reverse T3 was assessed by measurements in samples obtained from the internal carotid artery and jugular vein of sheep following the administration of thyrotropin releasing hormone (TRH) or bovine thyrotropin (TSH). Reverse T3 levels were increased 45-60 min after TRH administration, but TSH administration produced inconsistent alterations in reverse T3, although 18 of 27 samples obtained after TSH injection were higher than their average respective baseline concentration and the mean peak reverse T3 level was 14% higher than baseline. Following TRH administration to 10 normal human subjects, mean serum reverse T3 levels significantly increased from 53.6 ng/100 ml to 56.3ng/100 ml (P less than .05). The thyroid gland content of reverse T3 in human autopsy material was 6.5 +/- 1.5 microng/g tissue. Both pregnancy and estrogen administration were associated with increases in serum reverse T3 concentrations presumably because of their ability to augment thyroxine binding globulin synthesis.

Sensitivity to lithium in treated Graves' disease: effects on serum T4, T3 and reverse T3.

Seven patients judged to be euthyroid following treatment of diffuse toxic goiter were studied to determine if they were susceptible to lithium induced hypothyroidism. Lithium carbonate was administered for 4-7 weeks in a dosage (900 mg/day) which maintained serum lithium levels between 0.5-1.0 mEq/l. Blood was obtained weekly for the determination of serum 3,5,3'-triiodothyronine (T3), thyroxine (T4), 3,3',5'-TRIIODO-L-thyronine (reverse T3, rT3) and thyrotropin (TSH). Values observed during lithium therapy were compared to those obtained prior to, and approximately one week after discontinuing lithium. During the pretreatment preiod, mean (+/- SE) serum T3, T4, and rT3 concentrations were 130 +/- 21 ng/100 ml, 7.6 +/- 0.4 mug/100 ml and 48 +/- 8 ng/100 ml, respectively, and decreased during lithium administration with the lowest T3, T4 and reverse T3 concentrations of the lowest T3, T4 and reverse T3 concentrations of 92 +/- 8 ng/100 ml, 4.9 +/- 0.6mug/100 ml, and 33 +/- 6 ng/100, ml, respectively, being reached between the fourth and sixth weeks of study. Thereafter, and in spite of continued treatment with lithium, values for serum concentrations of T3, T4, and rT3 plateaued, or actually increased in 4, 6, and 5 subjects, respectively. Serum TSH concentrations remained 3.0 muU/ml or less throughout the study in 6 patients; 2 of these subjects had no TSH response to thyrotropin-releasing hormone (TRH), even though they had been euthyroid for 3 and 10 months. These data suggest that patients euthyroid following treatment of diffuse toxic goiter display sensitivity to the antithyroid effects of lithium. Furthermore, these observations support the thesis that the inhibitory effects of lithium and iodine upon thyroid hormone synthesis or secretion may involve a similar mechanism of action since increased thyroidal iodine content may be a consequence of therapy with either agent.

Iodothyronine levels in human cerebrospinal fluid.

Iodothyronines were measured by RIA in concentrated human cerebrospinal fluid (CSF). In measurements performed in one laboratory at a 4-fold concentration of CSF, rT3 was detected in all 30 patients in whom the measurement was attempted and averaged 15.1 +/- 2.8 ng/dl (mean +/- SE). IN an independent laboratory, rT3 measurements at this 4-fold concentration were performed on 11 different samples and averaged 9.3 +/- 0.9 ng/dl, while at a 40-fold CSF concentration, rT3 averaged 13.1 +/- 0.72 ng/dl. CSF T3 values were detected in only 4 of 30 patients as a 4-fold concentration and averaged 8.2 +/- 3.1 ng/dl, while in pooled CSF at a 40-fold concentration, 4 of 4 samples were detectable and averaged 2.6 +/- 0.4 ng/dl. Levels of T4 could only be detected in CSF concentrated 40-fold and averaged 0.22 +/- 0.04 microgram/dl. Values for the percent dialyzable thyronines were 0.44 +/- 0.03% for T4, 4.39 +/- 0.29% for T3, and 0.91 +/- 0.04% for rT3. TSH was detected in CSF concentrated 4-fold, averaging 0.43 +/- 0.05 microunits/ml; in an independent assay with CSF concentrated 40-fold, TSH averaged 0.06 +/- 0.02 microunits/ml. Thyroid binding globulin was undetectable (less than 0.1 mg/dl). We have confirmed the presence of thyroid hormones (T4 and T3) in human CSF and have shown that rT3 is present as well. The role these hormones play in the development, function, and nourishment of the central nervous system and the role the CSF plays in the transport of these hormones into the central nervous system remains to be determined.

Measurement of 3,3',5'-Triiodothyroinine (reverse T3), 3,3'-L-diiodothyronine, T3 and T4 in human amniotic fluid and in cord and maternal serum.

In order to assess fetal function at term, we have investigated parameters of thyroid hormone secretion and degradation in human amniotic fluid and in cord and maternal sera at delivery. The parameters measured included 3,3' L-diiodothyronine (3,3'T2), 3,3',5'-triiodothyronine (reverse T3), 3,3',5'-triiodothyronine (T3), thyroxine (T4), dialyzable T3 and T4, thyroxine binding globulin (TBG),and total iodine. The mean (+/- SE) 3,3'T2 concentrations in cord sera, amniotic fluid, and maternal sera were 20 +/- 1 ng/100 ml, 20 +/- 2 ng/100 ml,and 27 +/- 3 ng/100 ml, respectively. The normal range of this metabolite in the sera of non-pregnant adult subjects was 7 to 29 ng/100 ml. The mean (+/- SE) concentration of reverse T3 was higher in cord sera (315 +/- 16 ng/100 ml), amniotic fluid (82 +/- 25 ng/100 ml) and maternal sera (79 +/- 5 ng/100 ml) than in the sera of normal subjects (mean +/- 2 SD; 60 +/- 12 ng/100 ml). In amniotic fluid, T3, T4, and TBG were low, per cent dialyzable T3 and T4 were increased, and iodine concentrations were relatively normal in comparison to their respective serum levels in euthyroid adults. Since T3 and T4 were low in amniotic fluid our data indicate that measurements of 3,3'T2, reverse T3, or per cent dialyzable T3 and T4 in amniotic fluid would be the potentially most useful in establishing the diagnosis of congenital hypothyroidism before birth. In addition, these studies demonstrate that 3,3'T2 is normally present in the peripheral circulation and suggest that reverse T3 is the major source of 3,3'T2 in both amniotic fluid and cord blood.

A radioimmunoassay for 3',5'-diiodothyronine.

The present report describes a RIA for 3',5'-diiodothyronine (T2) that can be performed on unextracted serum and which has a lower limit of detectability of 2 ng/dl. Cross-reactivity with other iodothyronines was negligible, except for rT3 which began to demonstrate cross-reactivity when rT3 levels were elevated to 180 ng/dl. Employing this RIA for T2, we have determined that 83 healthy individuals had a mean (+/-SE) serum T2 concentration of 5.0 +/- 0.3 ng/dl, thyrotoxic subjects (n = 12) had a mean T2 level that was elevated to 10.8 +/- 0.8 ng/dl, and each of 6 hypothyroid subjects had undetectable (less than 2 ng/dl) concentrations. Athyreotic patients (n = 8), receiving 0.4 mg T4 daily, had serum T2 concentrations of 15.0 +/- 3.0 ng/dl. Fasting in obese subjects was associated with an increase in serum T2 to 6.9 +/- 0.6 ng/dl from a basal level of 4.4 +/- 0.4 ng/dl in the fed state (P less than 0.01). Despite the fact that rT3 levels may be elevated in amniotic fluid and that rT3 is expected to represent the major source from which extrathyroidal T2 arises, T2 levels were low in amniotic fluid, being undetectable (less than 2 ng/dl) in 9 of 19 samples; the mean (+/-SE) T2 concentration in the 10 detectable samples was 5.4 +/- 1 ng/dl. These data indicate T2 is a normal component of serum and that the majority of serum T2 is probably derived from peripheral conversion. Furthermore, these observations suggest that situations associated with elevated rT3 levels (e.g. thyrotoxicosis and fasting) may also have increased T2 values.

Glucagon kinetics in fasting: physiological elevations in serum 3,5,3'-triiodothyronine increase the metabolic clearance rate of glucagon.

We have attempted to determine if the elevated plasma glucagon concentration and delayed MCR of glucagon (MCRg) observed during caloric restriction are related to the decreased serum T3 that also occurs during fasting. Twelve obese subjects received a 3-h iv glucagon infusion during a 4-day fed period (1000 kCal/day) and again on approximately the third fasting day. Five patients fasted without receiving exogenous T3 (control group), whereas seven subjects fasted but also received 5 micrograms T3 orally every 4 h (T3 group) to maintain approximately the same serum T3 levels in the fed and fasting periods. Glucagon production rates (GPR) were derived by multiplying the MCRg by the respective basal plasma glucogon concentrations. In the control group, the MCRg was 442 +/- 55 ml/m2 . min in the postabsorptive state and decreased to 312 +/- 49 ml/m2 . min (P < 0.025) during fasting, whereas in the T3-treated group, the postabsorptive MCRg was 304 +/- 22 ml/m2 . min and increased during fasting to 417 +/- 47 ml/m2 . min (P < 0.025). The GPRs in the control group were statistically unaltered between the fed (27.7 +/- 3.0 ng/m2 . min) and fasted (22.9 +/- 1.8 ng/m2 . min) intervals, but GPR increased from 37.9 +/- 6.1 ng/m2 . min during fasting to 49.2 +/- 9.1 ng/m2 . min when T3 was administered (5 micrograms every 4 h). The net plasma glucose increment in response to glucagon decreased from 18 mg/dl (fed) to 5 mg/dl (fast) in the control patients and from 10 mg/dl (fed) to 7 mg/dl (fast) in the T3-treated subjects. In the T3-treated patients, serum T3 averaged 124 ng/dl during both feeding and fasting, and rT3 was 55 +/- 6 ng/dl during feeding and 49 +/- 5 ng/dl during fasting. In summary, the results from this study indicate that during fasting 1) slight physiological alterations in serum T3 influence the MCRg, and 2) T3 increases the GPR and blocks the customary fasting-induced rise in rT3. Conceivably, decreased T3 is an early event in the fasting state which serves to decrease the MCRg, a process which subsequently regulates glucose homeostasis.

Evaluation of a rapid and simple technique for the radioimmunoassay of triiodothyronine (T3).

This report compares T3 measurements obtained on the same serum samples by a resinstrip technique and by another existing radioimmunoassay method. The samples analyzed were obtained from a total of 90 subjects who were clinically categorized as hypothyroid, normal, hyperthyroid, or euthyroid while taking estrogen-containing compounds or while pregnant. The correlation coefficient for all 90 sera with these two different techniques was 0.94. All subjects who were clinically euthyroid (32) had a normal serum T3 concentration by the resin-strip technique. Similarly, 23 clinically hyperthyroid patients had elevated serum T3 concentrations and 15 of 17 clinically hypothyroid patients had decreased serum T3 levels.

Failure of 3,3'-diiodothyronine administration to alter TSH and prolactin responses to TRH stimulation.

In order to determine whether elevations in serum 3,3'-diiodothyronine (3,3'T2) concentrations influence the hypothalamic-pituitary--thyroid axis, thyrotropin (TSH) and prolactin responses to thyrotropin-releasing hormone (TRH) were assessed in five patients both prior to and during 3,3'T2 administration. Mean (+/- SE) peak TSH responses to TRH were 168 +/- 64 microU/ml during 3,3'T2 administration and 168 +/- 65 muU/ml during 3,3'T2 administration. Mean basal and peak prolactin concentrations after TRH were 6 +/- 3 ng/ml and 54 +/- 26 ng/ml, whereas during 3,3'T2 administration the basal and peak prolactin levels were 6 +/- 2 ng/ml and 55 +/- 28 ng/ml, respectively. Hypothyroid rats administered triiodothyronine (10 migrogram b.i.d.) for 5 days had a mean TSH response to TRH stimulation of 0.051 +/- 0.003 mU/ml, whereas rats to whom saline or 3,3'T2 (50 microgram b.i.d.) had been given for the same time interval had mean TRH-induced TSH responses of 1.127 +/- 0.179 mU/ml and 1.324 +/- 0.286 mU/ml, respectively. None of the TSH or prolactin responses to TRH, in either human or rat studies, were apparently altered by 3,3'T2. These observations suggest that elevation of serum 3,3'T2 levels are not associated with alterations in the hypothalamic--pituitary--thyroid axis in the experimental systems employed.

Parameters of thyroid function in patients with active acromegaly.

In order to determine if acromegaly per se may be associated with abnormalities in thyroidal economy, serum thyroxine-binding globulin (TBG), resin T3 uptake, total and free T4, T3, and reverse T3 concentrations were measured in 21 patients with active acromegaly. Mean (+/- SE) total T4, T3, and reverse T3 levels were 7.1 +/- 0.2 microgram/dl, 111 +/- 4 ng/dl, and 45 +/- 2 ng/dl, respectively, and the mean TBG concentration was 3.6 +/- 0.2 mg/dl. Similarly, mean free T4, T3, and reverse T3 concentrations were 2.4 +/- 0.09 ng/dl, 383 +/- 22 pg/dl, and 118 +/- 7 pg/dl, respectively. None of these values is significantly different from normal and the thyrotropin response to thyrotropin-releasing hormone was also normal. In contrast to several earlier reports, these data suggest that parameters of thyroid function are generally normal in patients with active acromegaly.

Photography in bite mark and patterned injury documentation--Part 1.

Photography is an important means of collecting and preserving physical evidence as it relates to bite mark and patterned injuries in skin. Proper use and understanding of color, black-and-white, ultraviolet and infrared photography can greatly aid the collection and preservation of evidence. The techniques and equipment for the photo-documentation of this evidence are presented.

Photography in bite mark and patterned injury documentation--Part 2: A case study.

A case involving multiple bite marks is presented. The bite marks were photographed over a 31-day period to document the injuries and preserve their evidentiary value. The evidence recovered at each photography session is discussed and photographs are presented for review. Suggestions concerning the need for more research are presented.

Human bite marks in forensic dentistry.

The scientific examination of bite-mark evidence is fascinating and challenging. As the science continues to evolve with more precise and demonstrative methods of performing the investigations and development of research data on the individuality of human dentition, the value of bite-mark analysis in the legal system will continue to increase. A quality bite-mark injury pattern examined properly using validated scientific methodologies can assist society greatly in applying laws fairly.

Cognitive therapy of substance abuse: theoretical rationale.

In this chapter, the authors assert that drug-related beliefs are an important factor in drug abuse and its treatment. Three types of acute drug-related beliefs have been described that contribute to urges, cravings, and ultimate use of drugs: anticipatory beliefs, relief-oriented beliefs, and permissive beliefs, and various ways have been described to assess more general, long-term beliefs pertinent to drug use. The role of the cognitive therapist is to assess, examine, and test these beliefs with the patient in order to ultimately develop more adaptive beliefs. The active application of skills and homework that tap into the patient's adaptive beliefs helps the patient to become and remain drug-free.