The Aboriginal and Torres Strait Islander casemix study

With increasing implementation of casemix-based funding for hospitals, quantitative data were needed to confirm the clinical impression that treating Aboriginal (compared with non-Aboriginal) inpatients consumes significantly more resources. Utilisation data, collected over a three-month period in 10 hospitals, were used to determine a cost per inpatient episode, which was grouped according to AN-DRG-3 to give a cost per AN-DRG for Aboriginal and Torres Strait Islander (ATSI) patients and non-ATSI patients. ATSI patients had consistently longer average length of stay and significant variation in relative frequency of admissions, compared with non-ATSI patients, with higher prevalences of infectious diseases. Degenerative and neoplastic conditions were more common in non-ATSI patients. There were significant differences in casemix-adjusted costs per patient episode (ATSI, $1856; non-ATSI, $1558; P < 0.001). Our study has quantified differential resource consumption between two Australian populations, and highlights the need for recognition of some hospitals' atypical populations and special funding requirements.

Australian encephalitis in the Northern Territory: clinical and epidemiological features, 1987-1996

BACKGROUND

The last epidemic of Australian encephalitis occurred in 1974. Since then, cases have been reported from the Kimberley of Western Australia (WA).

AIMS

To describe the epidemiology and clinical features of Australian encephalitis in the Northern Territory (NT) of Australia.

METHODS

Review of cases of Australian encephalitis presenting to Royal Darwin Hospital from 1987-1996 and review of sentinel chicken surveillance for Australian encephalitis viruses.

RESULTS

Sixteen patients were identified; ten from the NT and six from WA. Cases occurred in the years 1987, 1988, 1991 and 1993. Infection was acquired throughout northern NT below latitude 20 degrees S in the months March to July. All infections were due to Murray Valley encephalitis (MVE) virus. Eleven of the patients were children. Distinguishing features were spinal cord and brainstem involvement and the absence of seizures in adults. CT scanning was normal and EEG showed no focal activity. Five died (31%) and four (25%) have residual neurological disability. Sentinel chicken surveillance since 1992 shows yearly seroconversion to MVE virus throughout northern NT; human cases occurred simultaneously with chicken seroconversion in 1993.

CONCLUSIONS

Australian encephalitis is endemic in the NT; the areas at risk are north of Tennant Creek. Outbreaks are seasonal and occur every few years. Young children are most at risk. Mortality and morbidity are high. Prevention of disease is by avoidance of mosquito exposure and vector control measures.

Hospital use for potentially preventable conditions in aboriginal and Torres Strait Islander and other Australian populations

The poor state of Aboriginal and Torres Strait Islander health has been documented in many ways, most obviously by comparing the relatively higher age-specific mortality and morbidity rates. This paper demonstrates the use of acute hospital separation data as a way to identify potential deficiencies in providing appropriate primary health care services for Aboriginal and Torres Strait Islander populations. It does so by using 'ambulatory sensitive conditions': those conditions (and procedures) for which high-quality appropriate primary health services deliverable under ideal circumstances are though to potentially reduce or eliminate the need for hospitalisation. Potential or realised access to primary care is not analysed directly using primary health service data. In this study, 1993-94 acute hospital separation data from NSW, Queensland, South Australia, Western Australia and the Northern Territory were used to calculate separation rates and odds ratios for Aboriginal and Torres Strait Islander and non-Aboriginal and Torres Strait Islander populations. Age-specific acute hospital separation rates for ambulatory sensitive conditions were 1.7 to 11 times higher for the Aboriginal and Torres Strait Islander populations studied. This supports clinical contentions that much Aboriginal and Torres Strait Islander morbidity and mortality is preventable and that further consideration is needed to service delivery reform at all levels in the health system and the distribution of funding.

Cryptococcosis in HIV negative patients: findings on chest radiography

BACKGROUND

The findings at chest radiography in HIV negative patients with cryptococcosis are said to differ from those in HIV positive patients. No large series of HIV negative patients has been reported.

METHODS

A review of the medical charts and radiographs of 44 consecutive HIV negative patients with proven cryptococcosis was undertaken.

RESULTS

Air space consolidation involving one or more lobes was found in 15 patients (34%), one or more pulmonary masses in 13 patients (30%), and interstitial opacities in three patients (7%). No other radiographic finding was detected in more than one patient. Twelve of 23 patients (52%) with cryptococcal meningitis had abnormal chest radiographs, and 10 of 16 patients (62%) who presented with respiratory symptoms had air space consolidation.

CONCLUSIONS

HIV negative patients tend to have different radiographic findings from those reported in patients with AIDS. Cryptococcal meningitis in this group is usually associated with pulmonary mass(es) or a normal chest radiograph, whereas a respiratory presentation is usually associated with air space consolidation.

Isolation and characterization of PDE9A, a novel human cGMP-specific phosphodiesterase

We have cloned and characterized the first human isozyme in a new family of cyclic nucleotide phosphodiesterases, PDE9A. By sequence homology in the catalytic domain, PDE9A is almost equidistant from all eight known mammalian PDE families but is most similar to PDE8A (34% amino acid identity) and least like PDE5A (28% amino acid identity). We report the cloning of human cDNA encoding a full-length protein of 593 amino acids, including a 261-amino acid region located near the C terminus that is homologous to the approximately 270-amino acid catalytic domain of other PDEs. PDE9A is expressed in all eight tissues examined as a approximately 2. 0-kilobase mRNA, with highest levels in spleen, small intestine, and brain. The full-length PDE9A was expressed in baculovirus fused to an N-terminal 9-amino acid FLAG tag. Kinetic analysis of the baculovirus-expressed enzyme shows it to be a very high affinity cGMP-specific PDE with a Km of 170 nM for cGMP and 230 microM for cAMP. The Km for cGMP makes PDE9A one of the highest affinity PDEs known. The Vmax for cGMP (4.9 nmol/min/microg recombinant enzyme) is about twice as fast as that of PDE4 for cAMP. The enzyme is about twice as active in vitro in 1-10 mM Mn2+ than in the same concentration of Mg2+ or Ca2+. PDE9A is insensitive (up to 100 microM) to a variety of PDE inhibitors including rolipram, vinpocetine, SKF-94120, dipyridamole, and 3-isobutyl-1-methyl-xanthine but is inhibited (IC50 = 35 microM) by zaprinast, a PDE5 inhibitor. PDE9A lacks a region homologous to the allosteric cGMP-binding regulatory regions found in the cGMP-binding PDEs: PDE2, PDE5, and PDE6.

Isolation and characterization of PDE8A, a novel human cAMP-specific phosphodiesterase

As part of our efforts to understand the regulation of intracellular cAMP and to generate new targets for pharmacological intervention, we have cloned and characterized the first isozyme in a new family of cyclic nucleotide phosphodiesterases, PDE8A. PDE8A is most similar to PDE4 (38.5% amino acid identity in the catalytic domain), but is clearly not a member of any of the seven known PDE families. We report the cloning of human cDNA encoding the C-terminal 713 amino acids of the protein, including a 283 amino acid region located near the C-terminus that is homologous to the approximately 270 amino acid catalytic domain of other PDEs. In addition, we found cDNA sequences consistent with alternative 5' mRNA splicing analogous to that seen in other PDE genes. PDE8A is expressed in a wide variety of tissues as a approximately 4.5 kb mRNA, with highest levels in testis, ovary, small intestine, and colon. The C-terminal 545 amino acids of PDE8A (the region shared among all splice variants) were expressed in baculovirus. Kinetic analysis of the baculovirus expressed enzyme shows it to be a very high affinity cAMP specific PDE with a Km of 55 nM for cAMP and 124 microM for cGMP. The Vmax (150 pmol/min/microgram recombinant enzyme) is about 10 times slower than that of PDE4. The cAMP hydrolytic activity of PDE8A is not modulated by cGMP at concentrations up to 100 microM. The enzyme requires the presence of at least 1 mM Mn2+ or Mg2+ for maximal activity in vitro, while 100 mM Ca2+ restores only about 20% activity. PDE8A is insensitive (up to 100 microM) to a variety of PDE inhibitors including rolipram, zaprinast, vinpocetine, SKF-94120, and IBMX, but is inhibited (IC50 = 9 microM) by the PDE inhibitor dipyridimole. To give PDE8A a descriptive name that distinguishes it from the other two known high affinity cAMP-specific phosphodiesterases (PDE4 and PDE7), we denote PDE8A as the high affinity cAMP-specific and IBMX-insensitive PDE.

Urinary compound W in pregnant women is a potential marker for fetal thyroid function

OBJECTIVE

Previously we reported 3,3'-diiodothyronine sulfate-like material (compound W) in maternal serum, and studies suggest that compound W is derived from thyroid hormones of fetal origin. In this study we characterized gestational changes of urinary compound W concentrations to correlate with changes in serum concentrations.

STUDY DESIGN

Urinary samples were collected from 94 women at various gestational ages ranging from 3 to 40 weeks. Urinary compound W was first identified biochemically. The concentrations of compound W (adjusted for creatinine levels) were assessed by a 3,3'-diiodothyronine sulfate radioimmunoassay in ethanol extracts of urine samples.

RESULTS

Compound W increased to 88 +/- 1.4 pmol (of 3,3'-diiodothyronine sulfate equivalent)/mmol creatinine in urinary samples obtained from 26 women in the first trimester of pregnancy compared with 40 +/- 6.9 pmol/mmol creatinine in 10 nonpregnant women. Excretion of compound W increased further during the second and third trimesters: 171 +/- 17 (n = 18) and 434 +/- 26 (n = 50) respectively. In contrast, urinary 3,3',5-triiodothyronine sulfate concentrations measured by radioimmunoassay were similar during pregnancy to values in nonpregnant women.

CONCLUSIONS

Urinary compound W concentrations increase with the progression of normal pregnancy and correlate with the increase in serum levels. Random spot urine compound W concentrations, adjusted for creatinine levels, may be used in place of serum levels in conditions in which obtaining serum samples may be technically difficult, especially during population screening.

Penny ice cap cores, baffin island, canada, and the wisconsinan foxe dome connection: two states of hudson bay ice cover

Ice cores from Penny Ice Cap, Baffin Island, Canada, provide continuous Holocene records of oxygen isotopic composition (delta18O, proxy for temperature) and atmospheric impurities. A time scale was established with the use of altered seasonal variations, some volcanic horizons, and the age for the end of the Wisconsin ice age determined from the GRIP and GISP2 ice cores. There is pre-Holocene ice near the bed. The change in delta18O since the last glacial maximum (LGM) is at least 12.5 per mil, compared with an expected value of 7 per mil, suggesting that LGM ice originated at the much higher elevations of the then existing Foxe Dome and Foxe Ridge of the Laurentide Ice Sheet. The LGM delta18O values suggest thick ice frozen to the bed of Hudson Bay.

The medial trivector approach in total knee arthroplasty

This study compares the clinical results of the medial trivector approach to the standard parapatellar approach in primary total knee arthroplasty. Ten patients undergoing simultaneous bilateral total knee arthroplasty were included in this study. Right and left knees were randomized for a standard medial parapatellar arthrotomy or a medial trivector approach. Patients were assessed by the number of days to achieve straight leg raising and range of motion at discharge. In addition, knee scores were obtained at 6 weeks and 6 months with careful assessment of any pain or tenderness around the quadriceps mechanism. At 6 months, patients were tested on a KINCOM machine assessing their concentric and eccentric quadriceps strength. While there was no difference in total range of motion at the time of discharge, patients undergoing a medial trivector approach achieved independent straight-leg raising 2 days sooner than patients undergoing a standard medial parapatellar arthrotomy. No significant differences existed in knee scores, pain scores, or range of motion at 6 weeks or 6 months. KINCOM testing at 6 months revealed the knees undergoing trivector approach to be 15% stronger in concentric contractions. No complications were encountered with the use of the medial trivector approach in these patients. Subjectively, patients reported less discomfort and more strength in the knees having undergone a medial trivector approach. The medial trivector approach may enhance postoperative recovery without adversely affecting the quadriceps function following total knee arthroplasty. The medial trivector approach to the knee does not weaken quadriceps muscle function or adversely affect clinical results of total knee arthroplasty.

Effect of a patient management system on outcomes of total hip and knee arthroplasty

Five hundred fifty-three patients undergoing hip and knee reconstructive procedures in one institution that used a patient management system were compared with a retrospective group of 340 patients undergoing similar procedures in the same institution. All procedures were performed by one surgeon and the same patient management team. Measures of length of stay, discharge disposition, and hospital charges were recorded for all patients in each subgroup of total hip arthroplasty, revision total hip arthroplasty, total knee arthroplasty, revision total knee arthroplasty, unicompartmental knee arthroplasty, and bilateral procedures. The length of stay and hospital charges were reduced significantly in all groups, whereas the percentage of patients discharged to home was unchanged. There was no significant difference in complication rates between the two groups.

Cement-mantle thickness affects cement strains in total hip replacement

Bone cement is commonly used to affix femoral implants to the bone during total hip reconstruction. Previous studies suggest that the expected life of a cemented femoral implant may depend on the thickness of the cement mantle surrounding the implant and the implant geometry. The purpose of this study was to determine whether different cement-mantle thicknesses and femoral stem sizes affected strain patterns in the bone cement around cemented femoral stems. Two different sizes of cobalt-chromium stems were cemented into composite femora with varying cement-mantle thickness. Strain gages were embedded in the cement mantle and the implanted stems were loaded axially and under conditions simulating walking and standing. An increase in stem size with the same cement-mantle thickness (approximately 2.2 mm) caused a 65% decrease in proximal medial cement strains. Increasing cement mantle thickness from 2.4 to 3.7 mm caused substantial strain reductions in the distal cement (40-49%). We conclude that increased cement-mantle thickness around femoral stems may increase the fatigue life of a bone-implant system by reducing peak strains within the cement.

Cryptococcus neoformans var. gattii infection in northern Australia: existence of an environmental source other than known host eucalypts

The 2 known host trees of Cryptococcus neoformans var. gattii, Eucalyptus camaldulensis and E. tereticornis, do not occur naturally in the 'Top End' of the Northern Territory (NT) of Australia. Nine clinical isolates of C. neoformans var. gattii from the NT were analysed by random amplification of polymorphic deoxyribonucleic acid (RAPD) and polymerase chain reaction 'fingerprinting'. Two isolates were assigned to RAPD profile VGI, previously established as the common RAPD profile. The remaining 7 were assigned to profile VGII; 6 of these isolates were recovered from individuals living in the 'Top End'. The results strongly support the existence of an alternative environmental niche for C. neoformans var. gattii, as all isolates from Eucalyptus spp. in Australia to date have been of RAPD profile VGI.

Identification of a STAT6 domain required for IL-4-induced activation of transcription

Tyrosine phosphorylation of STAT6 in response to IL-4 results in the formation of STAT6 homodimers that bind specific DNA elements. Although binding sites for STAT6 have been shown to be important for the function of several IL-4-inducible promoters, the role of STAT6 in this activation has not been defined. To determine whether STAT6 is a transcriptional activator, different portions of the carboxyl terminus of STAT6 were fused to the yeast Gal4 protein DNA binding domain. Analysis of these chimeric Gal4-STAT6 proteins demonstrates that a 140-amino-acid proline-rich region of the carboxyl terminus of STAT6 contains a region that activates transcription. Truncation mutants of STAT6 that lack this domain cannot activate transcription and are capable of repressing transcription stimulated by a wild-type STAT6 protein. Strikingly, the ability of IL-4 to induce transcription from the Ig germline epsilon promoter is suppressed by overexpression of a carboxyl-terminal deletion mutant of STAT6. These studies demonstrate that the carboxyl terminus of STAT6 contains an activating domain required for the induction of genes by IL-4.

Hyponatremia of cirrhosis: role of vasopressin and decreased 'effective' plasma volume

BACKGROUND

The mechanism(s) of hyponatremia of cirrhosis is not completely clarified. Although increased vasopressin activity has been proposed in some studies, there have been reports disputing its role in the pathogenesis of profound hyponatremia in patients with decompensated liver disease. Methodologic flaws and lack of correlation with indices of circulatory dysfunction may have contributed to these discrepancies. The aims of the present study were to measure levels of vasopressin both in plasma and in urine and to correlate them with the volume-dependent hormonal systems of plasma renin activity (PRA) and atrial natriuretic factor (ANF).

METHODS

Plasma vasopressin, ANF, and PRA were measured by radioimmunoassay in 19 patients with cirrhosis, ascites, and severe hyponatremia (mean serum sodium, 121.8 mmol/l) and 11 patients with cirrhosis and normal serum sodium (mean, 137.6 mmol/l). Vasopressin levels were also assessed by radioimmunoassay in urine.

RESULTS

Patients with hyponatremia had higher plasma and urine vasopressin levels than patients with normal serum sodium concentrations (plasma, 2.9 versus 1.0 pg/ml, P = 0.0009; urine, 38.3 versus 12.3 ng/g creatinine, P = 0.0008). PRA was higher (4.8 versus 1.0 ng/ml/h, P = 0.0004) and plasma ANF lower (111.1 versus 148.7 pg/ml, P = 0.01) in patients with hyponatremia.

CONCLUSIONS

These results indicate that plasma and urine vasopressin levels are inappropriately increased in patients with cirrhosis and severe hyponatremia. The concomitant increase of PRA and decrease of plasma ANF suggest that decreased 'effective' plasma volume generates nonosmotic stimuli for vasopressin hypersecretion in these patients.

Identification of a STAT6 domain required for IL-4-induced activation of transcription

Tyrosine phosphorylation of STAT6 in response to IL-4 results in the formation of STAT6 homodimers that bind specific DNA elements. Although binding sites for STAT6 have been shown to be important for the function of several IL-4-inducible promoters, the role of STAT6 in this activation has not been defined. To determine whether STAT6 is a transcriptional activator, different portions of the carboxyl terminus of STAT6 were fused to the yeast Gal4 protein DNA binding domain. Analysis of these chimeric Gal4-STAT6 proteins demonstrates that a 140-amino-acid proline-rich region of the carboxyl terminus of STAT6 contains a region that activates transcription. Truncation mutants of STAT6 that lack this domain cannot activate transcription and are capable of repressing transcription stimulated by a wild-type STAT6 protein. Strikingly, the ability of IL-4 to induce transcription from the Ig germline epsilon promoter is suppressed by overexpression of a carboxyl-terminal deletion mutant of STAT6. These studies demonstrate that the carboxyl terminus of STAT6 contains an activating domain required for the induction of genes by IL-4.

Allergic contact dermatitis to propylene glycol in calcipotriene ointment

A woman developed a pruritic exacerbation of her methotrexate-dependent psoriasis after applying topical calcipotriene ointment. Patch test reactions were positive to propylene glycol 1 percent and white petrolatum, but to none of the other ingredients of the medication. Physicians would be advised to patch test patients to both the therapeutic medication and the excipients of topical substances to which patients have adverse reactions. By so doing, an allergic reaction to one or more of the excipients may be found, thus the patient may be provided the benefit of the topical medication by using it in a form that does not contain the allergenic substance.

Fetal thyroid function: diagnosis and management of fetal thyroid disorders

The fetal hypothalamic-pituitary-thyroid axis develops independently of the maternal axis, but it is dependent on the maternal-placental system for adequate supply of iodide substrate. This iodide is supplied by direct transfer of maternal plasma iodide and by placental deiodination of T4. In addition, although placental transport of iodothyronines is limited, significant maternal-fetal transfer of T4 occurs, accounting for approximately 30% of the average 10 ug/dL serum-T4 concentration in fetal-cord blood at term. Current information suggests that this maternal contribution to the fetal-T4 levels is important for normal fetal maturation, particularly of the central nervous system. Combined maternal-fetal hypothyroxinemia can lead to irreversible fetal central nervous system damage. The timing of this fetal T4 dependency is not clear. It may be important in the first half of gestation, before the fetal thyroid gland is capable of T4 production, as well as the latter half of gestation when thyroid hormone effects on multiple organ systems are developing. Management of fetal thyroid dysfunction requires normalization of maternal serum T4 concentrations, avoidance or careful monitoring of potentially goitrogenic drug effects in the fetus, and in some instances, direct or indirect fetal therapy. In most cases fetal hypothyroidism is sporadic and undetected, and prognosis for normal growth and development is excellent if the mother is euthyroid and the hypothyroid state is detected and adequately treated at birth. Fetal treatment by intraamniotic thyroxine injection has been provided in cases of inadvertent maternal radioiodine treatment of Graves' disease between 10 and 20 weeks gestation and for fetal goiter detected by ultrasound. Effective treatment of fetal hyperthyroidism in pregnant women with high titers of thyroid stimulating autoantibody is possible by judicious administration of antithyroid drugs to the mother. Management of the hyperthyroid state in the neonate also is essential.

Cloning and expression of a novel murine semaphorin with structural similarity to insect semaphorin I

We describe a novel semaphorin family member, Sema VIa, with 25-36% sequence identity at the amino acid level in the semaphorin domain to previously published mouse homologues. This novel family member shares considerable homology with the best characterized murine semaphorin, Sema III (also known as SemD), at the 5' end but is divergent from Sema III near the 3' end because it contains a putative transmembrane domain. Remarkably, of the known semaphorins, Sema VIa bears the greatest structural similarity to insect Sema I, although it contains a much larger intracellular domain. We propose, therefore, that Sema VIa is the prototype of a new class (class VI) of semaphorins. In order to gain insights into potential functions of Sema VIa, we have compared mRNA expression of Sema VIa to that of Sema III during development. In the nervous system, Sema VIa is expressed in strikingly localized and transient patterns that are markedly different from those of Sema III. Interestingly, Sema VIa and Sema III frequently exhibit complementary or adjacent loci of expression. We suggest that Sema VIa may be important to nervous system development via a mechanism that involves cell-cell communication.

CnNK-2, an NK-2 homeobox gene, has a role in patterning the basal end of the axis in hydra

NK-2-class homeobox genes have been identified in a variety of metazoans, from sponges to arthropods and vertebrates, and have been shown to play roles in a variety of cell and tissue specifications. Here we describe the characterization of the NK-2 homolog CnNK-2 from Hydra vulgaris, a freshwater cnidarian. CnNK-2 expression is restricted to the endodermal epithelial cells of hydra and is primarily in the peduncle, the lower end of the body column. In some species it is graded along the apical-basal axis with a maximum in the basal tissue of the lower peduncle, adjacent to the foot. CnNK-2 expression invariably precedes foot formation as part of the normal tissue dynamics of the adult as well as during asexual reproduction by budding, foot regeneration, or ectopic foot formation. Manipulations which alter the gradient of positional value along this axis affect CnNK-2 expression in a manner which indicates that expression of this gene is closely linked to the gradient. The normal and altered patterns of expression of this gene extend the understanding of the regulation of foot formation in hydra.

In vitro pharmacology of the novel phosphodiesterase type 4 inhibitor, CP-80633

We present the in vitro pharmacology of a novel adenosine 3'-5' -cyclic monophosphate-specific phosphodiesterase (PDE) type 4 inhibitor, CP-80633 ((2'S)5-[3-(2' -exobicyclo[2.2.1]-heptyloxy)4-methoxyphenyl] tetrahydro-2(1H)-primidone), which has shown efficacy in phase II clinical trials for atopic dermatitis. CP-80633 inhibits PDE4 isozymes (human lung IC50 = 1.27 microM) in the absence of effects on PDE1, PDE2, PDE3 and PDE5 isozymes (IC50 > 100 microM). It exhibits no significant selectivity for any single cloned PDE4A, B, C or D isoform. CP-80633 inhibits adenosine 3'-5'-cyclic monophosphate hydrolysis in partially purified human peripheral blood monocyte cytosol (IC50 = 3.52 microM), eosinophil membrane (IC50 = 1.10 microM) and T cell membrane (IC50 = 2.28 microM) preparations. Inhibition of eosinophil PDE4 adenosine 3'-5'-cyclic mono-phosphate hydrolysis by CP-80,633 occurs in a noncompetitive manner. Unlike theophylline, CP-80,633 is inactive against ratrain adenosine (A1,A2) receptors. Consistent with its action as a PDE4 inhibitor in whole cells, CP-80633 potentiates PGE1 dependent increases in adenosine 3'-5'-cyclic monophosphate levels in human U937 cells, and in human eosinophils, monocytes and T cells (EC200 approximately 1.0 microM). Consequently, CP-80633 inhibits many inflammatory cell functions including 1) human eosinophil superoxide anion production (IC50 < 0.6 microM), 2 C5a-(IC50 = 0.40 microM) and LTB4-(IC50 = 0.20 microM) mediated guinea pig peritoneal eosinophil chemotaxis and 3) lipopolysac-charide-induced tumor necrosis factor-alpha release from human monocytes (IC50 = 0.219 microM). These data clearly demonstrate that CP-80633 is a selective inhibitor of PDE4 isozymes, and support its potential use as a therapeutic agent for a number of inflammatory and immune disorders.

Physiological variations in thyroid hormones: physiological and pathophysiological considerations

Thyroid hormone production is regulated via pituitary thyrotropin (TSH) modulation of thyroxine (T4) prohormone secretion by the thyroid gland and regulation of active triiodothyronine (T3) production in peripheral tissues via metabolic events influencing activities of the iodothyronine monodeiodinase enzyme systems. Control at both levels is developmentally regulated and modified in serious nonthyroidal illness (trauma, infection, cancer, metabolic diseases). Racial and gender differences are of little significance except for the effects of placental estrogens and chorionic gonadotropin during pregnancy. There is a circadian rhythm of TSH secretion, with peak values at the onset of sleep and nadir concentrations during the afternoon hours. Peak and nadir concentrations differ by approximately +/- 50%. The effect on circulating T4 and T3 concentrations is not significant because of the large size of the extrathyroidal T4 pool. In healthy subjects there is no significant impact of body weight, physical training, body habitus, posture, immobilization, exercise, or ambulatory status on thyroid function, and no significant geographic environmental variation. Nutrition also has a minimal impact except for variation in iodine intake. Subthreshold concentrations of iodine intake are associated with increased TSH secretion, goiter, increased thyroid iodine uptake, decreased T4 production, an increased T3/T4 secretion ratio, and an increased ratio of circulating T3/T4 concentrations. Excessive iodine intake can block thyroid hormone biosynthesis by inhibiting the enzymes involved in the biosynthetic process, resulting in reduced T4 secretion, increased TSH concentrations, goiter, and hypothyroidism if the iodine excess is chronic.

Physiological variations in thyroid hormones: physiological and pathophysiological considerations

Thyroid hormone production is regulated via pituitary thyrotropin (TSH) modulation of thyroxine (T4) prohormone secretion by the thyroid gland and regulation of active triiodothyronine (T3) production in peripheral tissues via metabolic events influencing activities of the iodothyronine monodeiodinase enzyme systems. Control at both levels is developmentally regulated and modified in serious nonthyroidal illness (trauma, infection, cancer, metabolic diseases). Racial and gender differences are of little significance except for the effects of placental estrogens and chorionic gonadotropin during pregnancy. There is a circadian rhythm of TSH secretion, with peak values at the onset of sleep and nadir concentrations during the afternoon hours. Peak and nadir concentrations differ by approximately +/- 50%. The effect on circulating T4 and T3 concentrations is not significant because of the large size of the extrathyroidal T4 pool. In healthy subjects there is no significant impact of body weight, physical training, body habitus, posture, immobilization, exercise, or ambulatory status on thyroid function, and no significant geographic environmental variation. Nutrition also has a minimal impact except for variation in iodine intake. Subthreshold concentrations of iodine intake are associated with increased TSH secretion, goiter, increased thyroid iodine uptake, decreased T4 production, an increased T3/T4 secretion ratio, and an increased ratio of circulating T3/T4 concentrations. Excessive iodine intake can block thyroid hormone biosynthesis by inhibiting the enzymes involved in the biosynthetic process, resulting in reduced T4 secretion, increased TSH concentrations, goiter, and hypothyroidism if the iodine excess is chronic.

Antenatal diagnosis and treatment of fetal goitrous hypothyroidism: case report and review of the literature

The recognition and treatment of fetal hypothyroidism are believed to be important to optimize growth and intellectual development in affected fetuses. We present a case of fetal goiter diagnosed by ultrasonography in the second trimester of pregnancy. Cordocentesis performed at 28 weeks confirmed the presence of fetal hypothyroidism. Fetal therapy was performed with weekly intra-amniotic injections of thyroxine from 29 to 36 weeks. A repeat cordocentesis at 35 weeks showed normalization of fetal thyroid function. The fetal goiter decreased rapidly in size following fetal treatment. Amniotic fluid levels of thyroid stimulating hormone (TSH) and free thyroxine were obtained with each amniocentesis. Sulfated iodothyronine concentrations in maternal blood were obtained before and after fetal thyroxine treatment. This report discusses the role of amniotic fluid levels of TSH and free thyroxine and maternal levels of sulfated iodothyronine in the diagnosis and management of fetal hypothyroidism. A review of the English literature is presented.

Mucoepidermoid tumor of the lung: CT appearance

Mucoepidermoid tumor of the lung is a rare endobronchial neoplasm with a wide spectrum of appearance. We present a case report and describe the plain film and computed tomography (CT) findings.

Adverse effects of topical corticosteroid use

Topical corticosteroid use, a common and often efficacious therapy for a wide variety of cutaneous conditions, may have substantial adverse effects. These range from the notable nondermatologic side effects of hypothalamic-pituitary-adrenal axis suppression, Cushing's disease, femoral head osteonecrosis, and cataracts to a variety of less serious skin effects such as cutaneous tinea and contact dermatitis. The broad availability, efficacy, relative low cost, and ease of applying topical corticosteroids should not induce complacency or a cavalier attitude in prescribers. Physicians should have the same awareness of the possible side effects of topical steroid use as when prescribing parenteral medication.

Identification of 3,3'-T2S as a fetal thyroid hormone derivative in maternal urine in sheep

We measured 3,3'-diiodothyronine sulfate (T2S) in serum and urine (n = 5-6) obtained from euthyroid fetal (94-145 days of gestation, term = 150 days), newborn, and adult sheep and in serum and urine samples from ovine fetuses 13 days after total thyroidectomy conducted between 110 and 113 gestation days (n = 5). Sham-operated twin fetuses served as controls (n = 5). Mean serum T2S concentrations increased progressively from 94 days (74 ng/dl) to 130 days (420 ng/dl), decreasing thereafter to 145 days (197 ng/dl). T2S concentrations in fetal urine peaked at 110 days (117 ng/dl). In hypothyroid fetuses, mean serum and urine T2S were 60 and 53% of control values. To assess the possibility that the T2S in maternal serum/urine is derived from fetal serum 3,5,3'-triiodothyronine (T3), we measured T3, T3 sulfate (T3S), and T2S in fetal serum and in maternal serum and urine after bolus infusion of T3 to the fetus (n = 4). Additionally, T3, T3S, and T2S concentrations were measured in maternal serum and urine after T3 infusion to the maternal ewes (n = 4). Fetal T3 infusion rapidly increased fetal serum T3S and T2S. Maternal serum and urine T3S and T2S concentrations increased, whereas T3 concentrations remained unchanged. Maternal T3 infusion increased in serum and urine T3S and T2S levels, but the levels, relative to T3, were less than values measured after fetal T3 infusion. We conclude that T2S is a normal thyroid hormone metabolite in the ovine fetus and suggest that a major pathway of fetal T2S production is T3 to T3S to T2S.(ABSTRACT TRUNCATED AT 250 WORDS)

Intracellular sorting of neuromodulin (GAP-43) mutants modified in the membrane targeting domain

Neuromodulin (GAP-43) is a neurospecific calmodulin binding protein that is targeted to neuronal growth cones via fast axonal transport by an undefined mechanism. The protein is associated with membranes by palmitoylation of cys-3 and cys-4. The objective of this study was to examine the intracellular localization of neuromodulin and neuromodulin mutants modified in the membrane targeting domain of the protein in neurons and non-neuronal cells. The N-terminal palmitoylation domain of neuromodulin was found to be sufficient for membrane and Golgi targeting as well as neurite transport. A fusion protein consisting of the N-terminal 20 amino acids of neuromodulin and beta-galactosidase accumulated in neurite endings demonstrating that this sequence is sufficient for targeting to growth cone membranes. Mutations in the palmitoylation domain of neuromodulin that abolished its acylation and membrane association diminished its Golgi localization. Mutations that prevented Golgi accumulation of neuromodulin-beta-galactosidase fusion proteins also interfered with neurite transport of the fusion proteins. These data demonstrate a correlation between membrane targeting, Golgi localization, and neurite transport of neuromodulin.

Constrained acetabular cup disassembly

Dissociation of modular acetabular components in total hip arthroplasty has recently been reported. This case report describes two instances of polyethylene to metal dissociation with constrained polyethylene liners following total hip arthroplasty.