The effect of intra-operative hypotension on acute kidney injury, postoperative mortality and length of stay following emergency hip fracture surgery

The association between intra-operative hypotension and postoperative acute kidney injury, mortality and length of stay has not been comprehensively evaluated in a large single-centre hip fracture population. We analysed electronic anaesthesia records of 1063 patients undergoing unilateral hip fracture surgery, collected from 2015 to 2018. Acute kidney injury, 3-, 30- and 365-day mortality and length of stay were evaluated to assess the relationship between intra-operative hypotension absolute values (≤ 55, 60, 65, 70 and 75 mmHg) and duration of hypotension. The rate of acute kidney injury was 23.7%, mortality at 3-, 30- and 365 days was 3.7%, 8.0% and 25.3%, respectively, and median (IQR [range]) length of stay 8 (6-12 [0-99]) days. Median (IQR [range]) time ≤ MAP 55, 60, 65, 70 and 75 mmHg was 0 (0-0.5[0-72.1]); 0 (0-4.4 [0-104.9]); 2.2 (0-8.7 [0-144.2]); 6.6 (2.2-19.7 [0-198.8]); 17.5 (6.6-37.1 [0-216.3]) minutes, and percentage of surgery time below these thresholds was 1%, 2.5%, 7.9%, 12% and 21% respectively. There were some univariate associations between hypotension and mortality; however, these were no longer evident in multivariable analysis. Multivariable analysis found no association between hypotension and acute kidney injury. Acute kidney injury was associated with male sex, antihypertensive medications and cardiac/renal comorbidities. Three-day mortality was associated with delay to surgery ? 48 hours, whilst 30-day and 365-day mortality was associated with delay to surgery ≥ 48 hours, impaired cognition and cardiac/renal comorbidities. While the rate of acute kidney injury was similar to other studies, use of vasopressors and fluids to reduce the time spent at hypotensive levels failed to reduce this complication. Intra-operative hypotension at the levels observed in this cohort may not be an important determinant of acute kidney injury, postoperative mortality and length of stay.

Steroids to reduce the impact on delirium (STRIDE): a double-blind, randomised, placebo-controlled feasibility trial of pre-operative dexamethasone in people with hip fracture

Neuro-inflammation may be important in the pathogenesis of postoperative delirium following hip fracture surgery. Studies have suggested a potential role for steroids in reducing postoperative delirium; however, the potential efficacy and safety of pre-operative high-dose dexamethasone in this specific population is largely unknown. Conducting such a study could be challenging, considering the multidisciplinary team involvement and the emergency nature of the surgery. The aim of this study was to assess feasibility and effectiveness of dexamethasone given as early as possible following hospital admission for hip fracture, to inform whether a full-scale trial is warranted. This single-centre, randomised, double-blind, placebo-controlled study randomly allocated 79 participants undergoing hip fracture surgery to dexamethasone 20 mg or placebo pre-operatively. Eligibility and recruitment rates, timing of the intervention and adverse events were recorded. Incidence and severity of postoperative delirium were assessed using the 4AT delirium screening tool and the Memorial Delirium Assessment Scale. Postoperative pain, length of stay and mortality were also assessed. The eligibility rate for inclusion was 178/527 (34%), and 57/178 (32%) of eligible patients presented to hospital when no researcher was available (e.g. after-hours, weekends, public holidays). Recruitment was limited mainly by ethical limitations (not including patients with impaired cognition) and lack of weekend staffing. Median (IQR [range]) time from emergency department admission to drug administration was 13.3 (5.9-17.6 [1.8-139.6]) hours. There was a significant difference in delirium severity scores, favouring the dexamethasone group: median (IQR [range]) 5 (3-6 [3-7]) vs. 9 (6-13 [5-14]) in the placebo group, with the probability of superiority effect size being 0.89, p = 0.010. Delirium incidence did not differ between groups: 6/40 (15%) in the dexamethasone group vs. 9/39 (23%) in the placebo group, relative risk (95%CI) 0.65 (0.22-1.65), p = 0.360). A larger randomised controlled trial is feasible and ideally this should include people with existing cognitive impairment, seven days-a-week cover and a multicentre design.

TENS Alleviates Muscle Weakness Attributable to Attenuation of Ia Afferents

Quadriceps weakness is a notable problem following knee damage. Research has shown effectiveness of TENS in improving Quadriceps weakness associated with arthrogenic muscle inhibition. However, these studies were not focused upon short term delivery of TENS, nor did they examine the potential mechanism(s). The present study examined the effect of 25-30 s of TENS upon weakness induced temporarily by a prolonged vibration. Subjects performed eccentric MVCs under 2 conditions (TENS and no-TENS). First, MVC was measured at baseline. For the TENS condition, TENS was applied to each subject's knee joint during a second MVC measurement after vibration. For no-TENS condition, TENS was not applied during the 2^nd MVC measurement. MVC between pre-and post-vibration stimulation were compared across the 2 conditions. The results showed that MVC and EMG of TENS-condition was larger than that of no-TENS condition. Our results suggest that TENS could partially restore α-motoneuron activation, despite the induced dysfunctional γ-loop. These results suggest that mechanisms independent of the γ-loop such as a direct facilitation of the QF α-motoneuron pool by a long latency spinal-reflex and/or supraspinal mechanisms appear more likely to be responsible. The findings provide further support for utilizing TENS, even when γ-loop dysfunction is present following joint damage.

Predictors of persistent pain after total knee arthroplasty: a systematic review and meta-analysis

BACKGROUND

Several studies have identified clinical, psychosocial, patient characteristic, and perioperative variables that are associated with persistent postsurgical pain; however, the relative effect of these variables has yet to be quantified. The aim of the study was to provide a systematic review and meta-analysis of predictor variables associated with persistent pain after total knee arthroplasty (TKA).

METHODS

Included studies were required to measure predictor variables prior to or at the time of surgery, include a pain outcome measure at least 3 months post-TKA, and include a statistical analysis of the effect of the predictor variable(s) on the outcome measure. Counts were undertaken of the number of times each predictor was analysed and the number of times it was found to have a significant relationship with persistent pain. Separate meta-analyses were performed to determine the effect size of each predictor on persistent pain. Outcomes from studies implementing uni- and multivariable statistical models were analysed separately.

RESULTS

Thirty-two studies involving almost 30 000 patients were included in the review. Preoperative pain was the predictor that most commonly demonstrated a significant relationship with persistent pain across uni- and multivariable analyses. In the meta-analyses of data from univariate models, the largest effect sizes were found for: other pain sites, catastrophizing, and depression. For data from multivariate models, significant effects were evident for: catastrophizing, preoperative pain, mental health, and comorbidities.

CONCLUSIONS

Catastrophizing, mental health, preoperative knee pain, and pain at other sites are the strongest independent predictors of persistent pain after TKA.

Distinct transcriptional mechanisms direct expression of the rat Dmrt1 promoter in sertoli cells and germ cells of transgenic mice

DMRT1 is a transcription factor expressed only in Sertoli cells and undifferentiated spermatogonia of the postnatal testis, where it is required for proper cellular differentiation and fertility. To elucidate the transcriptional regulatory regions that provide DMRT1's cell-specific expression, transgenic mice containing a LacZ reporter gene driven by variable amounts of rat Dmrt1 5' flanking sequence, 9 kb and smaller, were evaluated. Examination of transgene expression by RT-PCR indicated that multiple promoter regions direct Dmrt1 to the testis and that sequences upstream of 2.8 kb are needed for both Sertoli cell expression and limiting transcriptional influence imposed by surrounding chromatin. Thus, whereas many of the transgenes were expressed in the testis, the ones with smaller promoters were significantly more prone to expression at ectopic sites or to complete silencing. Transgene expression in Sertoli cells and germ cells was assessed by immunohistochemistry and RT-PCR following busulfan treatment to remove germ cells. Both evaluations indicated expression of the 9- and 3.2-kb promoters in Sertoli cells and germ cells, whereas activity of smaller promoters was largely restricted to germ cells. In all, the present study provides in vivo evidence that distinct promoter sequences participate in Dmrt1 regulation in somatic cells and germ cells, with the -3.2 kb/-2.8 kb region directing expression in Sertoli cells and downstream sequences (< or =1.3 kb) directing it in germ cells. Further exploration of the mechanisms restricting Dmrt1 expression to the testis revealed that FOXL2, a transcription factor required for differentiation of the ovary, repressed Dmrt1 promoter through the -3.2 kb/-2.8 kb regulatory region, offering a potential mechanism for Dmrt1 transcriptional silencing in granulosa cells.

In vivo regulation of follicle-stimulating hormone receptor by the transcription factors upstream stimulatory factor 1 and upstream stimulatory factor 2 is cell specific

Pituitary FSH promotes pubertal timing and normal gametogenesis by binding its receptor (FSHR) located on Sertoli and granulosa cells of the testis and ovary, respectively. Studies on Fshr transcription provide substantial evidence that upstream stimulatory factor (USF) 1 and USF2, basic helix-loop-helix leucine zipper proteins, regulate Fshr through an E-box within its promoter. However, despite the strong in vitro support for USF1 and USF2 in Fshr regulation, there is currently no in vivo corroborating evidence. In the present study, chromatin immunoprecipitation demonstrated specific binding of USF1 and USF2 to the Fshr promoter in both Sertoli and granulosa cells, in vivo. Control cells lacking Fshr expression showed no USF-Fshr promoter binding, thus correlating USF-promoter binding to gene activity. Evaluation of Fshr expression in Usf1 and Usf2 null mice further explored USF's role in Fshr transcription. Loss of either gene significantly reduced ovarian Fshr levels, whereas testis levels were unaltered. Chromatin immunoprecipitation analysis of USF-Fshr promoter binding in Usf-null mice indicated differences in the composition of promoter-bound USF dimers in granulosa and Sertoli cells. Promoter-bound USF dimer levels declined in granulosa cells from both null mice, despite increased USF2 levels in Usf1-null ovaries. However, compensatory increases in promoter-bound USF homodimers were evident in Usf-null Sertoli cells. In summary, this study provides the first in vivo evidence that USF1 and USF2 bind the Fshr promoter and revealed differences between Sertoli and granulosa cells in compensatory responses to USF loss and the USF dimeric composition required for Fshr transcription.

Experimental Models for Nutritional Myopathy

Nutritional myopathy is a disease affecting young ruminants. The aetiological factors and their relative importance in disease development have been explored. A theoretical model has been developed and tested experimentally. The disease can be produced consistently using a recently developed vitamin E- and selenium-deficient diet. Disease can occur spontaneously in animals maintained on this diet alone over an extended period. Alternatively, myopathy can be induced in deficient animals by feeding polyunsaturated fatty acids such as linoleic and linolenic acid from corn and linseed oils respectively. For ruminants the oils are protected to prevent hydrogenation in the rumen. Because a similar protective mechanism appears to occur with normal ruminant forages such as grass, and the development of disease is so similar to that occurring naturally, polyunsaturated fatty acids are thought to play a major role in the development of the disease. The experimental disease reproduces extensive and consistent lesions of skeletal and cardiac myopathy. Hyaline necrosis occurs in the skeletal muscle fibres of many major muscle groups. In the heart the accumulation of droplets of lipofuscin-like pigment in Purkinje fibres is the initial lesion, followed by necrosis of Purkinje fibres and peri-Purkinje fibrosis. The accumulating pigment has been characterized by fluorescence spectroscopy and histochemical techniques. The cardiac pathology results in detectable electrocardiographic abnormalities and sudden death.

Sex-specific differences in mouse DMRT1 expression are both cell type- and stage-dependent during gonad development

Immunohistochemistry was used to examine GCNA1, a germ cell-specific protein, together with DMRT1 (Doublesex and Mab-3-related transcription factor-1), a transcription factor implicated in Sertoli cell and germ cell function, in order to resolve DMRT1's cellular profile during pre- and postnatal gonad development in the mouse. In the indifferent gonad (10.5-11.5 days postcoitus [dpc]), DMRT1 localized to somatic cells and GCNA1(+) germ cells and was indistinguishable in males and females. By 12.5 dpc, a clear sexual preference for DMRT1 in male somatic cells was observed, with male DMRT1 localized to testicular cords and more abundant in Sertoli cells than in germ cells and female DMRT1 diffusely labeled and markedly lower in somatic cells than in germ cells. A male somatic preference continued throughout development, with DMRT1 evident in Sertoli cells at all ages examined and absent in ovarian somatic cells from 13.5 dpc onward. In contrast, expression in primordial germ cells was not sexually distinct, and both sexes showed DMRT1 increasing through 13.5 dpc and absent by 15.5 dpc. Notably, sexual differences in germ cell DMRT1 were detected after birth, when it was detected only in spermatogonia of the testis. Colocalization of DMRT1 with proliferation markers KI67 and proliferating cell nuclear antigen (PCNA) and stem cell markers OCT4 (also known as POU5F1) and NGN3 indicated that, in postnatal testes, DMRT1 was present in both stem and proliferating spermatogonia. Together, the findings implicate opposite functions for DMRT1 in somatic and germ cells of the testis. In Sertoli cells, DMRT1 expression correlated with differentiation, whereas in germ cells, it suggested a role in expansion and maintenance of undifferentiated spermatogonia.

Expression of steroidogenic factor 1 in the testis requires an interactive array of elements within its proximal promoter

Steroidogenic factor 1 (SF-1) is an orphan nuclear receptor that is important for expression of genes involved in sexual differentiation, testicular and adrenal development, and hormone synthesis and regulation. To better understand the mechanisms required for SF-1 production, we employed transient transfection analysis and electrophoretic mobility shift assays to characterize the elements and proteins required for transcriptional activity of the SF-1 proximal promoter in testicular Sertoli and Leydig cells and adrenocortical cells. Direct comparison of SF-1-promoter activity in testis and adrenal cell types established that a similar set of regulatory elements (an E box, CCAAT box, and Sp1-binding sites) is required for proximal promoter activity in these cells. Further evaluation of the E box and CCAAT box revealed a novel synergism between the two elements and identified functionally important bases within the elements. Importantly, DNA/protein-binding studies uncovered new proteins interacting with the E box and CCAAT box. Thus, in addition to the previously identified USF and NF-Y proteins, newly described complexes, having migration properties that differed between Sertoli and Leydig cells, were observed bound to the E box and CCAAT box. Transient transfection analysis also identified several Sp1/Sp3-binding elements important for expression of SF-1 in the testis, one of which was previously described for expression in the adrenal gland whereas the other two were newly disclosed elements.

VLA-2 (alpha2beta1) integrin promotes rotavirus entry into cells but is not necessary for rotavirus attachment

In an attempt to identify the rotavirus receptor, we tested 46 cell lines of different species and tissue origins for susceptibility to infection by three N-acetyl-neuraminic (sialic) acid (SA)-dependent and five SA-independent rotavirus strains. Susceptibility to SA-dependent or SA-independent rotavirus infection varied depending on the cell line tested and the multiplicity of infection (MOI) used. Cells of renal or intestinal origin and transformed cell lines derived from breast, stomach, bone, or lung were all susceptible to rotavirus infection, indicating a wider host tissue range than previously appreciated. Chinese hamster ovary (CHO), baby hamster kidney (BHK-21), guinea pig colon (GPC-16), rat small intestine (Rie1), and mouse duodenum (MODE-K) cells were found to support only limited rotavirus replication even at MOIs of 100 or 500, but delivery of rotavirus particles into the cytoplasm by lipofection resulted in efficient rotavirus replication. The rotavirus cell attachment protein, the outer capsid spike protein VP4, contains the sequence GDE(A) recognized by the VLA-2 (alpha2beta1) integrin, and to test if VLA-2 is involved in rotavirus attachment and entry, we measured infection in CHO cells that lack VLA-2 and CHO cells transfected with the human alpha2 subunit (CHOalpha2) or with both the human alpha2 and beta1 subunits (CHOalpha2beta1) of VLA-2. Infection by SA-dependent or SA-independent rotavirus strains was 2- to 10-fold more productive in VLA-2-expressing CHO cells than in parental CHO cells, and the increased susceptibility to infection was blocked with anti-VLA-2 antibody. However, the levels of binding of rotavirus to CHO, CHOalpha2, and CHOalpha2beta1 cells were equivalent and were not increased over binding to susceptible monkey kidney (MA104) cells or human colonic adenocarcinoma (Caco-2, HT-29, and T-84) cells, and binding was not blocked by antibody to the human alpha2 subunit. Although the VLA-2 integrin promotes rotavirus infection in CHO cells, it is clear that the VLA-2 integrin alone is not responsible for rotavirus cell attachment and entry. Therefore, VLA-2 is not involved in the initial attachment of rotavirus to cells but may play a role at a postattachment level.

Preparation and properties of gallaborane, GaBH(6): structure of the gaseous molecule H(2)Ga(mu-H)(2)BH(2) as determined by vibrational, electron diffraction, and ab initio studies, and structure of the crystalline solid at 110 K as determined by X-ray diffraction

Gallaborane (GaBH(6), 1), synthesized by the metathesis of LiBH(4) with [H(2)GaCl](n) at ca. 250 K, has been characterized by chemical analysis and by its IR and (1)H and (11)B NMR spectra. The IR spectrum of the vapor at low pressure implies the presence of only one species, viz. H(2)Ga(mu-H)(2)BH(2), with a diborane-like structure conforming to C(2v) symmetry. The structure of this molecule has been determined by gas-phase electron diffraction (GED) measurements afforced by the results of ab initio molecular orbital calculations. Hence the principal distances (r(alpha) in A) and angles ( angle(alpha) in deg) are as follows: r(Ga.B), 2.197(3); r(Ga-H(t)), 1.555(6); r(Ga-H(b)), 1.800(6); r(B-H(t)), 1.189(7); r(B-H(b)), 1.286(7); angleH(b)-Ga-H(b), 71.6(4); and angleH(b)-B-H(b), 110.0(5) (t = terminal, b = bridging). Aggregation of the molecules occurs in the condensed phases. X-ray crystallographic studies of a single crystal at 110 K reveal a polymeric network with helical chains made up of alternating pseudotetrahedral GaH(4) and BH(4) units linked through single hydrogen bridges; the average Ga.B distance is now 2.473(7) A. The compound decomposes in the condensed phases at temperatures exceeding ca. 240 K with the formation of elemental Ga and H(2) and B(2)H(6). The reactions with NH(3), Me(3)N, and Me(3)P are also described.

Postmortem biochemical markers of experimentally induced hypomagnesaemic tetany in cattle

Severe hypomagnesaemia and tetany were induced in 10 lactating cows by feeding them semi-synthetic low magnesium diets and the animals were used to study the stability of postmortem markers of hypomagnesaemic tetany. There were significant relationships between the concentrations of magnesium in either cerebrospinal fluid (CSF) or plasma and either aqueous or vitreous humour. The onset of hypomagnesamic tetany was also associated with low magnesium concentrations in plasma, CSF and aqueous and vitreous humour. Magnesium concentrations less than 0.25 mmol/litre in fresh aqueous humour may be indicative of severe hypomagnesaemia and possible tetany in lactating cows, but the concentration of magnesium in aqueous humour was unstable postmortem. The concentration of magnesium in vitreous humour was relatively stable and a concentration of less than 0.55 mmol/litre could be used as a diagnostic marker of tetany in cattle for up to at least 48 hours postmortem, at ambient temperatures typical of Northern Ireland.

Expression of steroidogenic factor 1 in the testis requires an E box and CCAAT box in its promoter proximal region

Steroidogenic factor 1 (SF-1), also known as adrenal 4-binding protein, is a member of the nuclear hormone receptor family that regulates transcription of genes encoding hormones and steroidogenic enzymes important to the function of the hypothalamic-pituitary-gonadal axis. The mammalian Ftz-F1 gene encodes SF-1 and is required for development of adrenal glands and gonads. To better understand the mechanisms regulating this gene in the gonads, we have examined its expression in the testis and characterized the promoter region for SF-1 in two testicular cell types. SF-1 promoter activity was examined in primary cultures of Sertoli cells and cell lines representative of Sertoli and Leydig cells. Deletion mutagenesis of the promoter identified several regions: both 5' and 3' to the transcriptional start sites that are important for transcriptional activity. Two elements, an E box and a CCAAT box, were found to be important for SF-1 transcription in the testis. An oligodeoxynucleotide containing both of these elements bound three specific protein complexes. The binding of one complex required only sequences within the E box and cross-reacted with antibodies against the basic helix-loop-helix ZIP proteins USF1 and USF2. A second specific complex required sequences within both the E box and CCAAT box for efficient binding, while a third complex predominantly interacted with sequences within the CCAAT motif. The presence of multiple protein complexes binding these sites suggests that regulation through these elements may involve interactions with different factors that depend on the state of the cell and its environment.

Monochlorogallane: physical properties and structure of the gaseous molecule H2Ga(mu-Cl)2GaH2 as determined by vibrational, electron diffraction, and ab initio studies

Monochlorogallane, synthesized by the metathesis of gallium(III) chloride with an excess of trimethylsilane at ca. 250 K, has been characterized by chemical analysis, by its IR, Raman, and 1H NMR spectra, and by the products of its reaction with trimethylamine. The vibrational spectra of the vapor species isolated in solid Ar, N2, or CH4 matrixes at ca. 12 K imply the presence of only one species, viz. the dimer with an equilibrium structure conforming to D2h symmetry. The structure of this molecule has been determined by gas-phase electron diffraction (GED) measurements augmented by the results of ab initio molecular orbital calculations. An equilibrium structure with D2h symmetry has been assumed in the analysis of the electron diffraction pattern. However, as the molecule has a very low frequency Ga(mu-Cl)2Ga ring-puckering mode, a dynamic model was used to describe it with the aid of a set of pseudoconformers spaced at even intervals (deltadelta = 5 degrees, deltamax, = 20 delta) around the ring-puckering angle delta and Boltzmann-weighted according to a quartic potential V(delta) = V4delta4 + V2delta2. The differences in bond distances and angles between the different pseudoconformers were constrained to the values derived from the ab initio calculations employing second-order Moller-Plesset (MP2) methods (with all the electrons included in the correlation calculations) and a 6-311G(d) basis set. The results for the weighted average of the principal distances (ralpha) and angles (<alpha) (with estimated 1sigma uncertainties) from the combined GED/ab initio study are r(Ga-Cl) 2.350(2) A, r(Ga-H) 1.523(20) A, <Cl-Ga-Cl 89.7(5)degrees, <H-Ga-H 135.1 degrees, V4 3.0 x 10(-6) kcal mol(-1) deg(-4), and V2 6.0 x 10(-4) kcal mol(-1) deg(-2).

Reminding technology for prospective memory disability: a case study

Congenital or acquired brain damage resulting in prospective memory loss can make a child unable to become independent of care givers. This note describes a memory aid developed for a 17 year old with spina bifida and hydrocephalus who requires continual reminding to perform health maintenance tasks such as medication and feeding. Off-the-shelf computer hardware and software were used to make a reminding system that logged task completion information. Logging is a unique feature of this system, permitting review of the user's response to reminders for health or rehabilitative purposes. The system reduced the need to remind rate from > 75% to less than 10% of the time. Reminding rates returned to > 75% upon removal of the system. With the system this adolescent achieved more independent health maintenance. Weight and power requirements make this system embodiment impractical for general wheelchair use, but the technology in currently available pocket units may support the necessary functions.

Root surface removal with diamond-coated ultrasonic instruments: an in vitro and SEM study

Adequate root preparation in periodontal procedures includes the removal of plaque, calculus, and perhaps contaminated cementum and dentin. The purpose of this study was to evaluate and compare the amount of root surface removal and residual surface texture using similarly shaped regular (US) and both fine (FINDIAM) and medium (MEDDIAM) grit diamond-coated ultrasonic inserts. Forty-five (45) premolars extracted for orthodontic reasons were randomly divided into 3 groups of 15 teeth each. They were individually mounted in a jig and instrumented with a standardized 500 gram force while they were moved a precise horizontal distance of 12 mm over a 1.2 second period using specially designed and computer controlled instrumentation. Three measurements were made to the nearest 0.0005" at 3 points along the test area before instrumentation and after 10 and 20 strokes. The mean depth of root structure removed was US 5.8 +/- 6.6 microns, FINDIAM 50.1 +/- 14.2 microns, MEDDIAM 30.8 +/- 12.1 microns, after 10 strokes, and US 12.7 +/- 10.9 microns, FINDIAM 83.3 +/- 20.1 microns, MEDDIAM 58.7 +/- 17.9 microns after 20 strokes, respectively. All 3 instruments were different from each other (P < 0.001) in the 10 stroke group, while in the 20 stroke group FINDIAM and MEDDIAM were different from US (P < 0.001), but not from each other. Only FINDIAM showed a significant difference between 10 and 20 stroke values for depth of root removal. Modified loss of tooth substance index SEM scores indicated increasingly greater root surface roughness from US to FINDIAM to MEDDIAM. Substantially greater root surface removal and greater residual root surface roughness occurred with diamond-coated ultrasonic inserts under standardized in vitro conditions. These results suggest that caution should be used with diamond-coated ultrasonic instruments during periodontal root planing procedures.

Pancreas disease in Atlantic salmon (Salmo salar) and vitamin E supplementation

A study was instigated to investigate the histopathological and clinical pathological lesions associated with a naturally occurring pancreas disease (PD) outbreak in farmed Atlantic salmon. An attempt was made to reduce the severity of PD and associated lesions by altering the antioxidative and peroxidative substrates in the diets. The results do not support the hypothesis that PD leads to a vitamin E deficiency which induces a myopathy. PD was not associated with a reduction in tissue vitamin E concentrations. Despite high tissue vitamin E concentrations, pancreatic lesions and cardiac and skeletal myopathy occurred almost simultaneously. Severe myopathy appeared to be associated with high mortality. Dietary vitamin E concentrations > 500 mg/kg did not increase plasma and muscle vitamin E concentrations, which appear to be saturated. Liver concentrations were also high. However, differing concentrations of dietary vitamin E and fat were associated with differing mortality rates.

Determination of ivermectin residues in the tissues of Atlantic salmon (Salmo salar) using HPLC with fluorescence detection

A sensitive, accurate and reproducible assay for the determination of residual concentrations of ivermectin in the tissues of farmed Atlantic salmon is described. The assay employs the clean-up of an acetonitrile extract of salmon tissue on a Bond-Elut C8 column, followed by derivatization with trifluoroacetic acid anhydride. Following separation using HPLC, 22,23-dihydroavermectin B1a is determined using fluorescence detection. The limit of detection of the assay is 1 ng per g tissue. Liver, taken from fish treated experimentally with ivermectin, was found to contain higher concentrations of 22,23-dihydroavermectin B1a than any other tissue examined. The half-life of 22,23-dihydroavermectin B1a was similar in all tissues studied, ranging from 89 to 98 degree days.

Steroidogenic factor I, a key regulator of steroidogenic enzyme expression, is the mouse homolog of fushi tarazu-factor I

We proposed that a cell-selective regulatory protein coordinately regulates the expression of three enzymes that are required for the biosynthesis of corticosteroids: cholesterol side chain cleavage enzyme, steroid 21-hydroxylase, and the aldosterone synthase isozyme of steroid 11 beta-hydroxylase. In this report, we identify a 53-kilodalton protein, termed steroidogenic factor 1 (SF-1), that interacts with the related promoter elements from these steroidogenic enzymes, and we isolate and characterize a cDNA that very likely encodes this protein. We first showed that nuclear extracts from bovine adrenal glands interact with the mouse steroidogenic regulatory elements, forming complexes indistinguishable from those produced by nuclear extracts from mouse Y1 adrenocortical cells. These bovine adrenal extracts were subjected to sequential ion exchange and affinity chromatography to yield a highly enriched preparation of SF-1. The predominant protein in the affinity-purified preparation comigrated with shift activity and had a mol wt of 53,000; UV cross-linking experiments demonstrated directly that this 53-kilodalton protein interacted with the steroidogenic regulatory element. Even with this marked enrichment, affinity-purified SF-1 bound six steroidogenic regulatory elements. These results support strongly the model that a steroidogenic cell-selective protein interacts with related promoter elements from three steroidogenic enzymes to regulate their coordinate expression. The recognition sequence of SF-1 closely resembles those of nuclear hormone receptor family members, suggesting that SF-1 may belong to this supergene family. By screening a Y1 cell cDNA library with the DNA-binding region of the H-2RIIBP nuclear hormone receptor cDNA, we isolated a cDNA that is selectively expressed in steroidogenic cells. When expressed as a glutathione S-transferase fusion protein in Escherichia. coli, the protein encoded by this cDNA interacts with all six related steroidogenic regulatory elements with a binding specificity indistinguishable from that of SF-1. Surprisingly, the sequence of the putative DNA-binding domain of this cDNA matches exactly the corresponding sequence of the mouse homolog of the Drosophila transcription factor fushi tarazu-factor I. The demonstration that a member of the nuclear hormone receptor family interacts with the steroidogenic regulatory elements provides intriguing insights into possible mechanisms by which these essential genes are regulated.

Expression of a chimeric CaMV 35S Bacillus thuringiensis insecticidal protein gene in transgenic tobacco

Insecticidal transgenic tobacco plants containing a truncated Bacillus thuringiensis cryIA(b) crystal protein (ICP) gene expressed from the CaMV 35S promoter were analyzed for ICP gene expression under field and greenhouse conditions over the course of a growing season. We present new information on temporal and tissue-specific expression of a CaMV 35S/cryIA(b) gene. Levels of cryIA(b) protein and mRNA were compared in both homozygous and hemizygous lines throughout plant development. Levels of ICP mRNA and protein increased during plant development with a pronounced rise in expression at the time of flowering. Homozygous ICP lines produced higher levels of ICP than the corresponding hemizygous lines. ELISA analysis of different tissues in the tobacco plant showed ICP gene expression in most tissues with a predominance of ICP in older tissue. All transgenic ICP tobacco lines which were studied in the field and greenhouse contained 400 ng to 1 microgram ICP per gram fresh weight in leaves from the mid-section of the plant at flowering. The amounts of ICP produced by field lines were directly comparable to levels observed in greenhouse-grown plants.

Steroidogenic factor I, a key regulator of steroidogenic enzyme expression, is the mouse homolog of fushi tarazu-factor I

We proposed that a cell-selective regulatory protein coordinately regulates the expression of three enzymes that are required for the biosynthesis of corticosteroids: cholesterol side chain cleavage enzyme, steroid 21-hydroxylase, and the aldosterone synthase isozyme of steroid 11 beta-hydroxylase. In this report, we identify a 53-kilodalton protein, termed steroidogenic factor 1 (SF-1), that interacts with the related promoter elements from these steroidogenic enzymes, and we isolate and characterize a cDNA that very likely encodes this protein. We first showed that nuclear extracts from bovine adrenal glands interact with the mouse steroidogenic regulatory elements, forming complexes indistinguishable from those produced by nuclear extracts from mouse Y1 adrenocortical cells. These bovine adrenal extracts were subjected to sequential ion exchange and affinity chromatography to yield a highly enriched preparation of SF-1. The predominant protein in the affinity-purified preparation comigrated with shift activity and had a mol wt of 53,000; UV cross-linking experiments demonstrated directly that this 53-kilodalton protein interacted with the steroidogenic regulatory element. Even with this marked enrichment, affinity-purified SF-1 bound six steroidogenic regulatory elements. These results support strongly the model that a steroidogenic cell-selective protein interacts with related promoter elements from three steroidogenic enzymes to regulate their coordinate expression. The recognition sequence of SF-1 closely resembles those of nuclear hormone receptor family members, suggesting that SF-1 may belong to this supergene family. By screening a Y1 cell cDNA library with the DNA-binding region of the H-2RIIBP nuclear hormone receptor cDNA, we isolated a cDNA that is selectively expressed in steroidogenic cells. When expressed as a glutathione S-transferase fusion protein in Escherichia. coli, the protein encoded by this cDNA interacts with all six related steroidogenic regulatory elements with a binding specificity indistinguishable from that of SF-1. Surprisingly, the sequence of the putative DNA-binding domain of this cDNA matches exactly the corresponding sequence of the mouse homolog of the Drosophila transcription factor fushi tarazu-factor I. The demonstration that a member of the nuclear hormone receptor family interacts with the steroidogenic regulatory elements provides intriguing insights into possible mechanisms by which these essential genes are regulated.

Histopathologic and ultrastructural myocardial alterations in calves deficient in vitamin E and selenium and fed polyunsaturated fatty acids

We developed an experimental model of nutritional degenerative myopathy in ruminant cattle. Fourteen experimental calves were fed a diet low in vitamin E and selenium for 127 to 137 days. Six of these calves were then euthanatized. After 127 days, a dietary additive of linseed oil that had been treated to protect it against ruminal hydrogenation was added to the low vitamin E and selenium diet of the eight remaining calves as a source of polyunsaturated fatty acids. Six of these animals were euthanatized after 6 to 11 days of polyunsaturated fatty acid feeding; the other two died after 6 and 8 days. Macroscopic myocardial alterations were seen in five polyunsaturated fatty acid-fed calves but not in any other experimental calf. Microscopic lesions, comprising multifocal or diffuse cardiocyte degeneration and necrosis, were seen in atrial and ventricular myocardium of all experimental calves. These changes were more severe in polyunsaturated fatty acid-fed calves than in animals that did not receive polyunsaturates. Ultrastructurally, sublethally damaged cardiocytes had lysed contractile material; vacuolated sarcoplasm; altered mitochondria, sarcoplasmic myelin figures, and lipofuscin granules; and multiple nuclei. Necrotic cardiocytes had contracted myofibrils, pyknotic nuclei, mineralized mitochondria, and plasmalemmal disruption; the external lamina remained largely intact. Necrosis was followed by macrophage invasion and phagocytosis of necrotic debris. Repair of the lesions was by deposition of collagen and elastin fibers. No alterations were seen in the hearts of control calves fed vitamin E and selenium-supplemented diet. The induced myocardial lesions are similar to those of spontaneous nutritional degenerative myopathy in ruminant cattle.

A shared promoter element regulates the expression of three steroidogenic enzymes

The adrenal cortex of the mouse coordinately expresses three cytochrome P450 enzymes that are required for the biosynthesis of corticosteroids: cholesterol side-chain cleavage enzyme (SCC), steroid 21-hydroxylase (21-OHase), and steroid 11 beta-hydroxylase (11 beta-OHase). Within their 5'-flanking regions, we previously identified six elements containing variations of an AGGTC motif that regulated expression in mouse Y1 adrenocortical cells: 21-OHase elements at -210, -140, and -65; SCC elements at -70 and -40; and an 11 beta-OHase element at -310. We demonstrate here that all six elements interact with the same, or closely related, DNA-binding protein(s). First, these elements all formed complexes of similar mobility in gel shift assays, suggesting that they interacted with protein(s) of similar size. Additional larger complexes were seen with those probes containing exact AGGTCA sequences. Second, competition experiments confirmed that the factor(s) interacting with different elements had closely related or identical recognition specificities. Finally, indistinguishable profiles of shift activities were seen upon fractionation of nuclear proteins over sequential chromatographic columns. Collectively, these results suggest that related elements interact with a shared protein to regulate three essential steroidogenic enzymes. An AGGTCA sequence motif comprises the response element for several members of the nuclear hormone receptor family. Oligonucleotide competitions and specific effects of antisera in gel shift assays implicated chicken ovalbumin upstream promoter-transcription factor in the formation of the larger complexes seen with the elements containing exact AGGTCA sequences. Therefore, this member of the nuclear hormone receptor family also may regulate the expression of the adrenal steroidogenic enzymes.

Sequential changes in propionate metabolism during the development of cobalt/vitamin B12 deficiency in sheep

The changes in propionate metabolism that accompany cobalt deficiency in sheep are described. Two groups of sheep, fed either a cobalt sufficient or deficient diet, were given an iv propionate load at intervals during a 14 w experiment. There was a tendency towards increased propionate half-life as the animals became cobalt deficient. However, significant changes in the area under the plasma methylmalonic acid-time curve occurred very early, indicating significant impairment of propionate metabolism. Despite this, the area under the plasma glucose-time curve was unaffected by cobalt deficiency, suggesting that the impairment of propionate metabolism, although significant, is not extensive.

Analysis of the effects of astigmatism and misalignment on corneal surface reconstruction from photokeratoscopic data

This article presents a general method of error analysis for reconstruction algorithms employed by corneal topography systems and applies this method to assess the accuracy of the Wang reconstruction algorithms. Using mathematical surface reconstructions, the method detects artifacts introduced in topographic analysis by astigmatism and misalignment. For the Wang algorithms, error introduced by astigmatism was less than 1% of the true value for surfaces with more than 10.00 diopters of astigmatism. A 1-mm translational misalignment of the analyzed surface introduced error of no more than 1.3%. Errors caused by rotational misalignment were less than 3% for misalignments of 5 degrees or less. It is concluded from the error analysis method that the Wang algorithms are sufficiently accurate for use in the analysis of corneal topography. Similar analyses need to be accomplished for the validation of commercially available corneal topography systems.

Analysis of the promoter region of the gene encoding mouse cholesterol side-chain cleavage enzyme

The cholesterol side-chain cleavage enzyme (SCC) catalyzes the initial and rate-limiting step in the synthesis of steroid hormones. The mouse gene encoding SCC was cloned and the nucleotide sequence of its 5'-flanking region determined. This sequence includes an AP-1 motif at -319 and two motifs, AGGTCA at -70 and AGCCTTG at -40, that match elements proposed to be important in the expression of steroid 21-hydroxylase. When transfected into mouse Y1 adrenocortical tumor cells, 1.5 kilobase pairs of 5'-flanking region of the SCC gene directed high levels of expression of a growth hormone reporter gene; treatment of the transfected Y1 cells with 8-bromo-cAMP increased this expression by 5-fold. In contrast, transfected mouse MA-10 Leydig cells showed appreciably lower expression, suggesting that SCC expression in Leydig cells requires additional elements not contained in the 5'-flanking region of the SCC gene used in these experiments. Deletion experiments showed that 424 base pairs of 5'-flanking sequences were sufficient for regulated expression in Y1 cells and mapped two regulatory regions: one from -424 to -327 and a second from -219 to -77. DNase I footprinting and gel mobility shift analyses of these 424 base pairs defined several interactions between nuclear proteins and the SCC promoter, including footprints centered over the AP-1 motif, over a sequence at -120, and over the sequences (-70 and -40) that resemble 21-hydroxylase promoter elements. Finally, site-selected mutagenesis of the potential elements at -40, -70, or -120 decreased SCC promoter activity in transfected Y1 adrenocortical cells, thus establishing their importance in SCC expression.

Identification and characterization of two upstream elements that regulate adrenocortical expression of steroid 11 beta-hydroxylase

We have studied the mechanisms that regulate the expression of the mouse gene encoding steroid 11 beta-hydroxylase (11 beta-OHase), a steroidogenic cytochrome P450 enzyme that is expressed only in the adrenal cortex. DNase I footprinting and gel-mobility shift analyses revealed potential regulatory elements at -370 and -310 in the 11 beta-OHase promoter region. To determine the contributions of these elements to expression, we altered their sequences by site-selected mutagenesis and studied promoter activity after transfection into Y1 mouse adrenocortical tumor cells. Mutation of either element markedly decreased basal promoter activity but did not affect the response to treatment with 8-bromo cAMP. These experiments thus document the functional roles of these elements, within the context of the intact promoter, in constitutive expression of 11 beta-OHase. Moreover, addition of either of these elements to p-40GH, a 5'-deletion plasmid containing 11 beta-OHase sequences from -40 to +8 upstream of a growth hormone reporter gene, significantly increased promoter activity but did not confer cAMP responsiveness. Finally, increased expression was seen after transfection of Y1 derivatives deficient in cAMP-dependent protein kinase, indicating that neither element required cAMP-dependent protein kinase activity. These studies thus define two regulatory elements that play important roles in 11 beta-OHase expression.

Multiple regulatory elements determine adrenocortical expression of steroid 21-hydroxylase

Steroid 21-hydroxylase (21-OHase) is specifically expressed at high levels in the adrenal cortex, where it is required for the synthesis of mineralocorticoids and glucocorticoids. In this study, we have investigated the regulatory elements in the 21-OHase promoter region which contribute to the expression of this gene in Y1 adrenocortical cells. Eight potential regulatory elements in the 5'-flanking region of the 21-OHase gene were identified by DNase I footprinting and gel mobility shift experiments. Some of these footprints were produced by nuclear extracts from many cell lines, whereas other interactions were seen only when using nuclear extracts from Y1 adrenocortical and MA-10 Leydig tumor cells. Mutation of most of the elements markedly decreased the expression of a 21-OHase gene transfected into Y1 cells, thus documenting their functional importance for expression. Moreover, oligonucleotides containing the sequences of two related elements at -65 and -210, which share the heptamer AGGTCAG, increased the activity of a heterologous promoter in a Y1 cell-specific manner. Collectively, these results demonstrate that expression of 21-OHase in Y1 adrenocortical cells requires interactions among multiple cis-acting elements and regulatory proteins.

Structure-function studies of Na,K-ATPase. Site-directed mutagenesis of the border residues from the H1-H2 extracellular domain of the alpha subunit

It has recently been shown that replacement of the border residues (Gln-111 and Asn-122) of the H1-H2 extracellular domain of the sheep Na,K-ATPase alpha subunit with the charged amino acids Arg and Asp generates a ouabain-resistant enzyme (Price, E. M. and Lingrel, J. B. (1988) Biochemistry 27, 8400-8408). In order to further study structure-function relationships in Na,K-ATPase, six additional mutations have been made at these border positions. Two of these mutants were single amino acid substitutions (Gln-111 to Arg or Asn-122 to Asp). These mutations change one or the other H1-H2 border residue to a charged amino acid. The remaining substitutions were double mutants in which both of the H1-H2 border residues were simultaneously changed to charged amino acids. Changes were made which introduced either positively charged amino acids (Lys at positions 111 and 122), negatively charged amino acids (Glu at positions 111 and 122) or oppositely charged amino acids (Lys at position 111 and Glu at 122; Asp at position 111 and Arg at 122) at the borders of the H1-H2 extracellular domain. HeLa cells transfected with any of these sheep Na,K-ATPase alpha subunit mutants were able to grow in concentrations of ouabain that were toxic to untransfected cells or cells transfected with the wild type sheep alpha subunit. Crude membranes isolated from the transfectants were analyzed for ouabain inhibitable Na,K-ATPase activity. All of the transfectants contained a relatively ouabain-resistant component of enzyme activity, with the ouabain I50 values ranging from 4 x 10(-3) M to 1 x 10(-6) M. The most resistant enzyme was the double mutant that contained Asp at position 111 and Arg at 122, whereas the least resistant were the enzymes containing the single amino acid substitutions. There was no correlation between the type of charged amino acid present at the border position and the degree of ouabain resistance. These data demonstrate the functional importance, in terms of ouabain binding, of the border positions of the H1-H2 extracellular domain of the Na,K-ATPase alpha subunit.

Survey of levels of propetamphos and diazinon used to control sheep scab in Northern Ireland

As a result of an increase in the incidence of sheep scab in Northern Ireland, the concentrations of propetamphos and diazinon were measured during 1987 and 1988 in fleece and liquid dip samples from selected flocks, including some in which inadequate dipping was suspected. Sixty-five per cent and 68 per cent of the liquid dip samples contained less than the manufacturer's recommended maintenance concentrations for propetamphos and diazinon respectively. The concentrations found in fleece were also lower than those found in sheep which were dipped with the recommended concentrations of propetamphos and diazinon in a controlled experiment.

Site-directed mutagenesis of a conserved, extracellular aspartic acid residue affects the ouabain sensitivity of sheep Na,K-ATPase

Site-specific mutagenesis was used to study the function of a conserved, extracellular aspartic acid residue from the sheep Na,K-ATPase alpha subunit. This amino acid, Asp-121, is the penultimate residue of the first extracellular domain of the alpha subunit. The border residues of this particular extracellular loop of the alpha subunit have been shown to be determinants of ouabain sensitivity (Price, E. M., and Lingrel, J. B. (1988) Biochemistry 27, 8400-8408). In order to determine if Asp-121 is involved in ouabain binding, five different amino acid substitutions at this position were generated. Four of the five mutant alpha subunits, containing either Asn, Ala, Glu, or Ser in place of Asp-121, conferred ouabain resistance to HeLa cells when expressed in those cells. Cloned sublines of cells selected in ouabain were characterized in terms of ouabain-inhibitable cell growth and Na,K-ATPase activity. The cells expressing the mutant Na,K-ATPase alpha subunit containing either Asn, Ala, Glu, or Ser in place of Asp-121 contained a component of Na,K-ATPase activity that was nearly 100-times more resistant to ouabain than the endogenous HeLa (human) or sheep enzyme. Apparently, conservative (Glu for Asp), isosteric (Asn for Asp), and nonconservative (Ala or Ser for Asp) substitutions all significantly decreased ouabain sensitivity. These data suggest that Asp-121 of the sheep Na,K-ATPase alpha subunit participates in the binding interaction between the enzyme and ouabain.

Vitamin E, selenium, and polyunsaturated fatty acid concentrations and glutathione peroxidase activity in tissues from pigs with dietetic microangiopathy (mulberry heart disease)

Tissues of 27 pigs with spontaneous dietetic microangiopathy (DM) and of 27 control pigs that died of causes unrelated to vitamin E and selenium (E-Se) deficiency were analyzed for alpha-tocopherol, Se and polyunsaturated fatty acid (PUFA) concentrations and for glutathione perioxidase (GSH-Px) activity. These variables (except for GSH-Px) also were measured in rations fed to control pigs and pigs with DM. Swine with DM had lower heart and liver alpha-tocopherol concentrations than did control pigs. Heart and kidney Se concentrations and heart and liver PUFA concentrations were similar in pigs of either group. Diets fed to both groups of pigs contained similar content of alpha-tocopherol, Se, oil, and PUFA; alpha-tocopherol and Se concentrations in the diets of both groups of pigs were high. In spite of apparently adequate amount of dietary alpha-tocopherol, results indicate that pigs with DM had lower tissue alpha-tocopherol concentration than did control pigs. Spontaneous DM is associated with altered alpha-tocopherol metabolism, but is unrelated to alterations in dietary Se and PUFA contents and tissue Se and PUFA concentrations and GSH-Px activity.

Methylmalonic acid in the diagnosis of cobalt deficiency in barley-fed lambs

Eight lambs were fed on a cobalt-deficient whole-barley diet supplemented with urea, vitamins and minerals. Four control lambs were fed on the same diet which had been further supplemented with Co. Plasma vitamin B12 levels in the Co-depleted group declined rapidly, falling below the normal range within 5 weeks. Differences between the live weights of the animals in the two groups approached statistical significance by week 14. However, methylmalonic acid (MMA) rose above normal levels in the Co-depleted group within 7 weeks. This suggested that an elevated plasma concentration of MMA is a comparatively early indicator of functional vitamin B12 deficiency. It is recommended that 10 mumol/l be the upper level of normality for plasma MMA concentration in barley-fed animals, in contrast with the level of 5 mumol/l for grass-fed animals. Changes in the plasma concentrations of MMA and ethylmalonic acid associated with feeding the barley-based diet per se did not significantly affect the validity of the gas-liquid chromatographic assay for MMA.

A new reconstruction algorithm for improvement of corneal topographical analysis

Accurate methods for the analysis of corneal topography are essential for the evaluation and management of corneal refractive errors. Photokeratoscopy has been used clinically to evaluate corneal shape anomalies, and methods have been developed to reconstruct the shape of the corneal surface from keratoscope photographs. However, the 2-dimensional information on the keratoscope image is insufficient for uniquely reconstructing a 3-dimensional corneal surface. Algorithms currently used make assumptions necessary for calculation, but lead to considerable error, especially at the periphery of radially aspheric corneas. This article proposes an improved algorithm that avoids some of the earlier assumptions for improved accuracy. The new algorithm was tested on both spherical and aspherical calibration surfaces. The result of this algorithm is identical to earlier methods for spherical surfaces, but the new method substantially increases accuracy in reproducing the aspherical surfaces at the cost of increased computation time.

Sequential changes in plasma methylmalonic acid and vitamin B12 in sheep eating cobalt-deficient grass

Methylmalonic acid (MMA) concentrations are elevated in plasma as a result of vitamin B12 deficiency. This study reports the sequential changes in plasma MMA in lambs maintained on a cobalt-deficient pasture compared with supplemented controls. The results indicate that MMA is elevated in the early stages of deficiency, preceding the onset of loss of production and clinical signs of disease. It remains elevated as long as the lambs are unsupplemented with cobalt (Co). The most striking clinical sign was a loss of body condition as opposed to weight. The defect in the methylmalonyl CoA mutase is obviously an early defect in cobalt deficiency.

A cAMP-responsive element regulates expression of the mouse steroid 11 beta-hydroxylase gene

In Y1 mouse adrenocortical tumor cells, expression of steroid 11 beta-hydroxylase (11 beta-OHase) is stimulated by cAMP following a delay of 4-6 h. Our results demonstrate that a cAMP-responsive element (CRE) within the 11 beta-OHase promoter region is a major determinant of this induction. The 5'-flanking sequences from the mouse 11 beta-OHase gene were placed in front of a human growth hormone reporter gene and transfected into Y1 cells. Treatment of transfected cells with 8-bromo-cAMP increased expression directed by the 11 beta-OHase 5'-flanking region by 3.8-fold. In 5'-deletion analyses, 123 base pairs of 5'-flanking sequences were sufficient for cAMP induction, whereas cAMP treatment did not affect expression of a plasmid with only 40 base pairs of 5'-flanking sequence. Within these 123 base pairs, a region from -56 to -49 matched 7 of 8 bases comprising the consensus sequence for the CRE. 11 beta-OHase 5'-flanking sequences from -65 to -42, including the CRE-like sequence, conferred cAMP inducibility to promoters from the thymidine kinase and chorionic gonadotropin alpha-subunit genes. DNase I footprinting and Southwestern blotting analyses demonstrated that the protein which interacted with the CRE in the 11 beta-OHase promoter region was similar to the CRE-binding protein associated with other cAMP-regulated genes. Together, these results suggest that an interaction between the 11 beta-OHase CRE and CRE-binding protein mediates cAMP induction of the 11 beta-OHase gene.

The roles of cAMP and cAMP-dependent protein kinase in the expression of cholesterol side chain cleavage and steroid 11 beta-hydroxylase genes in mouse adrenocortical tumor cells

The expression of the genes encoding cholesterol side chain cleavage enzyme (SCC) and steroid 11 beta-hydroxylase (11 beta-OHase) was examined in Y1 mouse adrenocortical tumor cells and in derivative cell lines defective in cAMP-dependent protein kinase activity. Y1 cells expressed both genes constitutively, and treatment with 8-bromo-cAMP (8-Br-cAMP) increased expression 5-10-fold. In three independent protein kinase mutants, expression of SCC and 11 beta-OHase was impaired to degrees dependent upon the severity of defect in cAMP-dependent protein kinase activity. In Kin-2, the least impaired mutant clone, basal expression of SCC was the same as in Y1 cells. Treatment of Kin-2 with 8-Br-cAMP increased SCC RNA to the levels seen in stimulated Y1 cells. In contrast, clone Kin-8, the most severe mutant, expressed markedly diminished basal and 8-Br-cAMP-stimulated levels of SCC mRNA. Kin-7 had basal and 8-Br-cAMP-stimulated levels of SCC mRNA which were intermediate to Kin-2 and Kin-8. None of the Kin mutants constitutively expressed detectable levels of 11 beta-OHase transcripts, and only Kin-2 responded to treatment with 8-Br-cAMP with increased expression of 11 beta-OHase; however, the time course of induction in Kin-2 was significantly delayed. The disparate patterns of expression of SCC and 11 beta-OHase in the Kin mutants suggest that these genes differ in their absolute requirement for cAMP-dependent protein kinase activity. Experiments also were performed in which Kin-7 and Kin-8 mutants were restored to cAMP-responsive states by transfection with genes encoding normal sub-units of cAMP-dependent protein kinase. These phenotypic revertants recovered 8-Br-cAMP-inducible expression of SCC and 11 beta-OHase. These results strongly support the hypothesis that impaired expression of steroidogenic enzymes in the Kin mutants results directly from defects in cAMP-dependent protein kinase activity.

Determination of chlortetracycline residues in tissues using high-performance liquid chromatography with fluorescence detection

A method is described for the determination of chlortetracycline residues in tissue samples. The samples were extracted into a hydrochloric acid - glycine solution and the extracts concentrated and purified on cyclohexyl-bonded reversed-phase cartridges. Any chlortetracycline present was converted to iso-chlortetracycline at pH 12, which was then separated from interfering compounds on a reversed-phase polymeric column using high-performance liquid chromatography with fluorescence detection. The detection and determination limits of the assay were 20 and 50 ng g-1, respectively, making it suitable for statutory residue testing purposes.

Structural and functional analysis of the promoter region of the gene encoding mouse steroid 11 beta-hydroxylase

The mouse gene encoding adrenal steroid 11 beta-hydroxylase (11 beta-OHase) has been cloned and the nucleotide sequence of its 5' end has been determined. The coding regions sequenced are homologous (75%) to the sequence of bovine 11 beta-OHase cDNA. The 5'-flanking region of the 11 beta-OHase gene contains a potential cAMP response element (TGACGTGA) located 56 base pairs upstream of the transcription initiation site (position -56) and two motifs at positions -249 and -148 which are similar to an element postulated to be required for the expression of 21-hydroxylase. Transfection of mouse Y1 adrenocortical tumor cells and MA-10 testicular Leydig cells with plasmids containing the 11 beta-OHase promoter linked to a growth hormone reporter gene showed that the 11 beta-OHase promoter can direct cell-specific expression. Deletion analyses of the 5'-flanking region suggest that multiple sequence elements, one of which is located between positions -425 and -338 and a second between positions -338 and -123, interact to produce full levels of promoter activity. Mutant Y1 cells defective in cAMP-dependent protein kinase activity do not express growth hormone driven by the 11 beta-OHase promoter, indicating that expression of 11 beta-OHase in Y1 cells requires an intact cAMP second messenger system. Moreover, mutation of the putative cAMP response element at position -56 abolishes expression. These experiments thus present a useful system for the investigation of cis-acting elements involved in the transcriptional regulation of 11 beta-OHase.

Regulation of 21-hydroxylase gene expression

The steroid 21-hydroxylase (21-OH) gene is selectively expressed in the adrenal cortex and is transcriptionally regulated by ACTH. We examined the role of the 5'-flanking sequences of 21-OH in this regulated expression by analyzing their ability to direct the expression of a human growth hormone (hGH) reporter gene upon transfection into Y1 mouse adrenocortical tumor cells. The 330 bp of 5'-flanking sequences directed basal and hormonally-inducible expression of hGH in Y1 cells, but did not direct expression in I-10 mouse testicular Leydig cells. Both constitutive and hormonally-inducible expression required a functional cAMP-dependent protein kinase. These results indicate that the first 330 bp of 5'-flanking sequences of the 21-OH gene contain sufficient information for cell-specific and hormonally regulated expression, and that this expression requires the integrity of cAMP-dependent protein kinase. Markedly lower expression of hGH was seen when 156 bp of 5'-flanking sequences were placed in front of the reporter gene, suggesting that sequences between -330 and -156 are essential for expression. The addition of sequences from -330 to -150 to the p-156GH plasmid, in either the correct or the reverse orientation, restored promoter activity to approximately the level obtained with the 330 bp of 5'-flanking sequences. Moreover, the addition of sequences from -230 to -150 increased by 5-fold the expression of hGH driven by the heterologous thymidine kinase promoter. Based on these results, we conclude that an enhancer element is contained within the sequences from 230 to 150 bp upstream of the transcription initiation site.