The significance of a positive test of morphine cholescintigraphy in hospitalized patients

Morphine-augmented radionuclide cholescintigraphy (MC) is a useful adjunctive diagnostic tool for the identification of acute cholecystitis (AC) in patients who are hospitalized and critically ill with occult sepsis. The results of previous studies have demonstrated a reduction in false-positive rates, that is, nonvisualization, from 40 percent with standard radionuclide cholescintigraphy to 5 percent with MC in these high-risk patient groups, with an overall accuracy of 92 percent. This study was performed to determine the significance of a positive test result from MC in patients with occult sepsis. We reviewed the records of all 20 patients at high risk in whom MC was positive during the 35-month period ending 31 May 1992. AC was confirmed by laparotomy in all 16 patients who underwent surgical treatment. There were two patients who recovered with antibiotic therapy alone (considered false-positives) and two additional patients who died without operation or a confirmed diagnosis of AC (excluded from analysis). Thus, in this series, MC was associated with a positive predictive value of 0.89, confirming that it is a valuable adjunct in establishing the diagnosis of AC in patients who are seriously ill and hospitalized with occult sepsis.

Ablation of remaining functioning thyroid lobe with radioiodine after hemithyroidectomy for carcinoma

Nineteen patients who had hemithyroidectomy as a surgical procedure for thyroid cancer were given radioiodine to ablate the residual hemithyroid. Two different protocols were used, with either a larger single dose or multiple smaller doses. Ablation was achieved in 28% with the single large dose approach and in 33% of patients given split doses of similar total amount. This response to the initial attempt at eradication of the residual normal hemithyroid is considerably lower than the accepted ablation rate with comparable doses administered to patients with small thyroid residues after total thyroidectomy. It is suggested that the effect of radioiodine treatment may relate inversely to the size of the thyroid remnant. Our findings also are in support of the surgical approach advocating total thyroidectomy for patients contemplating ablation of thyroid residues after surgery for thyroid carcinoma.

The usefulness of the dynamic phase in pertechnetate thyroid imaging for solitary hypofunctioning nodules

One hundred patients, each with a solitary thyroid nodule detected by clinical palpation, underwent three-phase Tc-99m pertechnetate thyroid imaging. The degree of perfusion of the thyroid nodule was classified as hypo-perfused, euperfused, or hyperperfused compared to the remainder of the gland by a consensus of three nuclear medicine physicians. The nodules were subsequently biopsied, and the degree of perfusion of the nodules was correlated with their histologic diagnosis. Twenty-two nodules were classified as hyperperfused, 64 as euperfused, and 14 as hypoperfused. Malignancy rates of the hyperperfused, euperfused, and hypoperfused nodules were 36%, 31% and 0%, respectively. This seems to indicate that malignant thyroid nodules demonstrate a degree of perfusion at least equal to or greater than the rest of the thyroid gland. Conversely, none of the hypoperfused nodules was found to be malignant. The perfusion phase of thyroid imaging may provide useful clinical information regarding possible malignancy of a thyroid nodule.

SJL/J resistance to mouse hepatitis virus-JHM-induced neurologic disease can be partially overcome by viral variants of S and host immunosuppression

The basis of the resistance of SJL/J mice to various strains of mouse hepatitis virus (MHV) has been the subject of some debate, especially as it relates to the number and nature of the determinants involved. Our previous work demonstrated that resistance by primary SJL/J glial cultures may involve events subsequent to viral gene expression, possibly due to a defect in cell-to-cell spread of the infection. Since S, the virion's major spike glycoprotein, is known to facilitate the spread of infection due to its syncytiogenic properties, we decided to investigate the role of this viral structural protein in resistance by primary SJL/J glial cells. Variants possessing deletions within the S coding region were able to grow in SJL/J glial cells 10-100 times easier and fuse five-times more efficiently than wt virus. Induction of neurologic disease in SJL/J mice following intracranial inoculation with either wt JHMV or the S deletion variant, AT11f cord, was age-dependent, occurring only in animals inoculated under 4 weeks of age. Resistance in older animals to wt and variant viruses could be abrogated by immunosuppression with cyclosporin A. However, both disease incidence and viral brain titers were higher in animals receiving the JHM variant AT11f cord virus, suggesting that SJL/J resistance to neurologic disease may manifest itself through interactions between inefficient cell-to-cell spread of the infection and protective aspects of the immune response.

A developmentally regulated gene encodes the dictyostelium homolog of yeast ribosomal protein S4 and mammalian LLRep3 proteins

We report the sequence and expression of a single-copy gene from Dictyostelium discoideum which encodes the homolog of yeast ribosomal protein S4, a protein located on the small ribosomal subunit and known to play an important role in maintaining translational fidelity. Over a highly conserved central region, the Dictyostelium protein has 78% sequence similarity to the yeast protein and 83% sequence similarity to mammalian S4 protein homologs, the LLRep3 proteins. The Dictyostelium gene encodes a polypeptide 28,717 Da in size and hence this ribosomal protein has been named rp29. The N-terminal sequence of the Dictyostelium rp29 protein is extended by 61 amino acids and 14 amino acids compared to the mammalian and yeast proteins, respectively, and the C-terminus is correspondingly 15 amino acids or 2 amino acids shorter. Although the coding region of the rp29 gene is present on a single exon, a 157bp intron interrupts the 5' untranslated region and unusually contains four direct repeats of the sequence TCAATCT. The gene is expressed maximally during vegetative growth but a second peak of expression also occurs late in development which is restricted to prestalk cells; rp29 is the first Dictyostelium ribosomal protein gene reported which shows prestalk-specific developmental expression. During each round of expression, only a single 0.9kb transcript is produced which is similar in size to the yeast S4 ribosomal protein transcript (0.8kb) but markedly smaller than the mammalian LLRep3 mRNA (1.7kb) due to a much shorter 5' untranslated region.

Spatiospectral and picosecond spatiotemporal properties of a broad area operating channeled-substrate-planar laser array

Spatiospectral and spatiotemporal properties of an eight-element channeled-substrate-planar laser array are investigated in both cw and pulsed operating conditions. The closely spaced CSP array with strong optical coupling between array elements is characterized by a broad area laserlike operation determined by its spatial mode spectra. The spatiotemporal evolution of the near and far field exhibits complex dynamic behavior in the picosecond to nanosecond domain. Operating parameters for the laser device have been experimentally determined. These results provide important information for the evaluation of the dynamic behavior of coherent semiconductor laser arrays.

Association of high density lipoprotein cholesterol with plasma lipolytic activity and C-peptide concentration in type 2 diabetes

In order to assess whether insulin concentration or plasma lipolytic activity has any role in the regulation of HDL cholesterol concentrations in type 2 diabetes, fasting plasma C-peptide and HDL2-cholesterol concentrations and the post-heparin plasma activities of lipoprotein lipase and hepatic endothelial lipase were measured in 148 patients with type 2 diabetes (76 male, 72 female). HDL2-cholesterol was related negatively to hepatic lipase activity in men (r = -0.49, p less than 0.001) and women (r = -0.43, p less than 0.001) and positively to lipoprotein lipase activity in men (r = -0.33, p less than 0.01) and women (r = 0.36, p less than 0.01). A significant inverse relationship was confirmed between C-peptide and the HDL2-cholesterol subfraction in both sexes (men, r = -0.40, p less than 0.001, women r = -0.51, p less than 0.001). This persisted after adjustment for the effects of alcohol intake, mode of hypoglycaemic treatment, plasma glucose and body mass index. The relationship was lost in men and greatly diminished in women when hepatic lipase activity was included in multiple linear regression analysis, whereas the inclusion of lipoprotein lipase activity in the analysis had little effect on the relationship between C-peptide and HDL2-cholesterol. We suggest that hepatic lipase may be partly responsible for the commonly observed inverse relationship between measures of insulin secretion and HDL-cholesterol concentrations. We speculate that this may occur through a direct stimulatory effect of insulin on the enzyme's activity.

Accumulation of noradrenaline and its oxidation products by cultured rodent astrocytes

The accumulation of [3H]noradrenaline ([3H]NA) and its oxidation products was studied in primary cultures of cerebral astrocytes. Astroglial accumulation of radiolabeled catecholamine ([3H] NA and oxidation products) was enhanced by manganese or iron, but it was inhibited by unlabeled NA, dopamine or ascorbate. Tissue: medium ratios of radioactivity increased as extracellular [3H]NA was oxidized. When extracellular oxidation was prevented by ascorbate, as confirmed by high performance liquid chromatography with electrochemical detection, either ouabain pretreatment or nominally Na(+)-free incubation medium inhibited approximately one-half of specific [3H]NA accumulation by rat (but not mouse) astrocytes. These observations suggest that neurological responses to trace metals and ascorbate may arise from the effects of these agents on the clearance of extracellular catecholamines. Astrocytes can accumulate oxidation products of NA more rapidly than they take up NA itself, but ascorbate at physiological concentrations prevents the oxidation process in extracellular fluid. Furthermore, in the presence of ascorbate, Na(+)-dependent transport mediates a significant component of NA accumulation in rat astrocytes.

Fractionated doses of radioiodine for ablation of postsurgical thyroid tissue remnants

Patients who have differentiated thyroid carcinoma and have undergone total thyroidectomy are treated with radioiodine for ablation of functional thyroid remnants. Administration of a single therapeutic dose in excess of 30 mCi of l-131 requires hospitalization. In an attempt to obviate the necessity for hospitalization, the prospective ablative dose was divided into two or three fractions given at weekly intervals on an ambulatory basis. To assess the effectiveness of this approach, this group of patients was compared to a cohort of hospitalized patients treated with a single dose. Ablation was achieved in 9 out of 12 patients treated in a fractionated manner (a 75% success rate), whereas in 16 out of 20 patients given a single dose the thyroid remnants were completely eradicated (an 80% success rate). That the use of split, smaller doses administered at weekly intervals on an ambulatory basis presents a reasonable alternative for ablation of postsurgical, residual-functioning thyroid tissue.

In vivo and in vitro models of demyelinating disease. Possible relationship between induction of regulatory subunit from cAMP dependent protein kinases and inhibition of JHMV replication in cultured oligodendrocytes

The results in this study suggest a unique possible association between inhibition of JHMV replication and the induction of R1 proteins in differentiating oligodendrocytes, involving inhibition of a PPPase found in the endosome fractions of cells. Free R1 protein appears to prevent the dephosphorylation of purified JHMV-NC substrate thereby possibly blocking the normal sequence of events necessary for NC release of viral genomes. Inhibition of host-cell endosome PPPase's may have relevance to controlling JHMV infection since CV particles adsorbing to cell surface receptors are believed to penetrate via clathrin coated pits into endosomes. Thus, the early stages of CV infection, including dephosphorylation of NC protein within endosomes, provide a possible site for controlling the initial stages of viral infection.

The reduction of low density lipoprotein cholesterol by metformin is maintained with long-term therapy

Changes in serum lipoproteins were studied in 14 non-insulin dependent diabetics on long-term metformin therapy, after 6 weeks' placebo, and again 6 weeks after restarting active drug therapy. Withdrawal of metformin resulted in a rise of fasting blood glucose, HbA1, serum total and low density lipoprotein (LDL) cholesterol. Restarting the drug reversed these changes. Multivariate analysis showed that serum total and LDL cholesterol varied with treatment but not with glycaemic control. Metformin can lower serum total and LDL cholesterol in non-insulin dependent diabetics and this effect is maintained long term.

The effect of glibenclamide and metformin on serum lipoproteins in type 2 diabetes

In a cross-over study, the effects of 3 months treatment with metformin or glibenclamide on body weight, blood glucose control, and serum lipoproteins were compared in 35 Type 2 diabetic patients, inadequately controlled by dietary therapy alone. Glibenclamide alone increased body weight (mean change +2.75 kg; 95% confidence intervals +1.95 to +3.55 kg; p less than 0.0001). Glibenclamide and metformin achieved equivalent blood glucose control, independent of initial body mass index. Neither drug affected serum triglyceride concentration. Metformin alone significantly reduced low density lipoprotein cholesterol (mean change -0.34 mmol l-1; 95% confidence intervals -0.12 to -0.57 mmol l-1; p less than 0.01). Neither drug altered high density lipoprotein or subfraction cholesterol.

In vivo and in vitro models of demyelinating disease: efficiency of virus spread and formation of infectious centers among glial cells is genetically determined by the murine host

Resistance or susceptibility of various mouse strains to central nervous system disease caused by different strains of coronavirus is well known. Data from the present study draw attention to an additional, genetically determined mechanism controlling CV infections. The resistance to A59 and JHM virus (JHMV) associated with SJL mice was maintained in explanted glial cultures which, by contrast, fully supported a productive infection by the serorelated mouse hepatitis virus type 3. A comparative analysis of the infectious process in glial cell explants from SJL and CD.1 mice helped to define the stage at which restriction is manifested. Cultures of oligodendrocytes and astrocytes from these strains of mice were challenged with JHMV or mouse hepatitis virus type 3, and cell-virus interactions were monitored, including adsorption, uptake of inoculum, transcription, and cell-to-cell dissemination. The sequence of early events from adsorption to genome activation occurred with about equal efficiency with both viruses and genetically different cells, indicating that SJL resistance is not due to any deficiency in specific receptors or penetration of the inoculum or general expression of viral functions. However, intercellular spread of the infection was restricted in SJL glial cells owing to an as yet undefined component. Since cells from (SJL x CD.1)F1 mice were fully susceptible to JHMV, resistance to virus spread must be due to a deficiency in some factor, perhaps a proteolytic activity necessary for dissemination.

The interleukin-2 receptor and its expression in the acute leukaemias and lymphoproliferative disorders

The expression of the interleukin-2 receptor (IL-2R) was investigated in a total of 117 cases of acute leukaemia and lymphoproliferative disorder. The results confirm reports that the interleukin-2 receptor can be expressed on cells of myeloid lineage and in cases of Hairy Cell Leukaemia. They extend knowledge of the expression of the IL-2R in cases of lymphoproliferative disorders.

Transferrin receptor expression in the leukaemias and lymphoproliferative disorders

The expression of the transferrin receptor (TfR) was studied in the acute leukaemias and lymphoproliferative disorders by means of indirect immunofluorescence and/or the enhanced alkaline phosphatase anti-alkaline phosphatase (APAAP) techniques using monoclonal antibodies to the receptor. A total of 174 cases of acute leukaemia and lymphoproliferative disorder were studied. The results indicate that the receptor is expressed with increased density in the majority of positive cases of acute leukaemia. The lymphoproliferative disorders, however, only expressed the receptor in a minority of cases and did so with weak density. It is proposed that this weak expression in the lymphoproliferative disorders may be of use as an indicator of an increase in cell activity.

Technetium Tc 99m plasmin in the diagnosis of inflammatory disease

The localization characteristics of technetium Tc 99m plasmin were studied in experimental animals to investigate the use of 99mTc-plasmin for imaging inflammatory processes. At various times after abscess induction using turpentine in rats, the in vivo distribution properties of 99mTc-plasmin, gallium citrate Ga 67, 125I-fibrinogen, and 99mTc-human serum albumin (HSA) were studied by gamma-camera imaging. The in vivo binding of each radiopharmaceutical was also tested in rat and human plasma clots. Region-of-interest analyses of gamma-camera images showed relatively poor 99mTc-plasmin localization at sites of abscess formation. The ratio of abscess-to-control activity of this radiopharmaceutical did not exceed that of 67Ga, 125I-fibrinogen, or 99mTc-HSA. In vitro assays of each of the radiopharmaceuticals in plasma clots showed 99mTc-plasmin and 125I-fibrinogen to have the best localization characteristics.

In vivo and in vitro models of demyelinating diseases, XX: Replication of coronaviruses in primary neural cultures from genetically resistant and susceptible mice

Resistance of SJL mice to JHMV could be associated with explanted oligodendrocytes and astrocytes in primary neural cultures from newborn mice. The restriction demonstrated is not at the stage of adsorption, uptake by the host or RNA synthesis and does not occur with the serorelated MHV3 strain. Experiments with neural cells from F1 hybrid mice bred from resistant and sensitive parents show that resistance is a recessive trait. It is hypothesized that the defect may involve proteolysis at the cell surface, but to date no clear cut experimental data have been obtained to substantiate this idea. In more general terms our in-vitro observations demonstrate that resistance of SJL mice pertains to both embryonic and newborn animals and involves neural and non neural cell types. Thus, the SJL restriction of JHMV, evident at the cellular level, does not involve an age-related maturation process associated with rat and mouse oligodendrocytes studied previously (1, 14).

In vivo and in vitro models of demyelinating diseases. XV. Differentiation influences the regulation of coronavirus infection in primary explants of mouse CNS

Mouse oligodendrocytes and astrocytes, in primary cerebral explant cultures, were infected with JHMV and MHV3 coronaviruses. Contrary to previous findings with neural cells from the rat (S. Beushausen and S. Dales, 1985, Virology 141, 89-101), these agents show no discrimination in the tropism and have the ability to replicate in either type of murine glial cell. Effects of the differentiation inducer dbcAMP on levels of the myelinspecific enzyme 2':3'-cyclic nucleotide-3'-phosphohydrolase (CNPase) activity and virus replication were determined. In the mouse system there was a gradual, continuous elevation of CNPase beyond 30 days whereas in comparable rat cell cultures maximum CNPase enhancement is elicited within 21 days (F. A. McMorris, 1983, J. Neurochem. 41, 506-515). After dbcAMP treatment replication of both coronaviruses was profoundly suppressed in murine oligodendrocytes, consistent with our findings on JHMV replication in treated rat oligodendrocytes. By contrast the replication of JHMV and MHV3 in dbcAMP-treated murine astrocytes was influenced only marginally. These findings provide further support for the hypothesis that susceptibility of rodents to CNS infection by coronaviruses is determined, in part, by the age-related maturation process of oligodendrocytes.

Stimulatory effect of forskolin on gastric acid secretion in the rat, in vitro and in vivo

The effect of forskolin, a potent adenylate cyclase activator, was studied on rat gastric acid secretion in vitro and in vivo. In the isolated gastric mucosa, forskolin was 25 and 100 times more potent than histamine and dibutyryl cyclic AMP respectively, with an EC50 of 2 microM and a maximum effect at 8-10 microM. In the lumen-perfused anaesthetised rat, acid secretion in response to a series of bolus i.v. injections of forskolin failed to show dose dependency, despite dose-related hypotensive effects. Secretory responses to i.v. infusions of forskolin were dose-related and were associated with a rise in gastric mucosal blood flow despite marked hypotension. These results indicate that forskolin has a direct secretagogue effect on parietal cells which, under some circumstances may be modified by its other pharmacological actions.

Factor invariance and the Life Satisfaction Index

This investigation of the Life Satisfaction Index (LSI) supports findings by Hoyt and Creech (1983) that indicate Adams' (1969) proposed factor structure is not invariant across groups. Two reduced factor models, proposed by Hoyt and Creech and based on a subset of LSI items, were studied with our sample (two levels each of income and age, N = 791). Our work confirms that the Hoyt and Creech 8-item LSI reveals the more stable factor structure of those examined. In addition, we found that the 8-item index has adequate statistical power to be of benefit to those investigators looking at quantitative differences in life satisfaction, with reasonable assurance that older and/or higher-income individuals are interpreting the items in similar ways.

Subcutaneous emphysema after extraction of maxillary teeth: report of a case

Inappropriate use of dental equipment that is powered by highly compressed air may directly lead to the formation of subcutaneous emphysema that involves the fascial planes of the head and neck. The high-speed dental handpiece and the air and water dental syringe are the instruments that are most commonly implicated in the reported cases. The treatment of such cases requires a reassured patient, prophylactic antibiotic coverage, and close postoperative follow-up care. Patients should avoid maneuvers that could increase intraoral pressure. Complete resolution should be expected within one week.

The effect of immediate access to a computerized medical record on physician test ordering: a controlled clinical trial in the emergency room

We performed a randomized clinical trial of the effect of immediately printed summaries of a computerized medical record on physician test ordering rates in an Emergency Room setting. The computerized medical record contained medication history, the results of most diagnostic studies, an outpatient problem list, and inpatient and emergency room diagnoses. Physicians were presented with a printed summary of the patient's computerized record for study but not for control encounters. All other patient information was equally available to both kinds of encounters. All results were provided for one period of the study, designated T1. Due to a program error, summaries were printed without recent data during a period of the study, designated T2. Two-thirds of the visits were cared for by internists, one-third by surgeons. During T1, internists ordered an average of 3.2 tests, costing $34.91 for control visits, and 2.7 tests, costing $29.94 for study control visits (p less than .026). Surgeons also ordered fewer tests during study visits as compared to controls (1.32 vs 1.54) but the differences were not statistically significant. There was no significant effect on either medical or surgical test ordering during time period T2.

Effects of inhibitors of 5-hydroxytryptamine uptake on plasma glucose and their interaction with 5-hydroxytryptophan in producing hypoglycaemia in mice

The effects of various inhibitors of 5-HT uptake on plasma glucose have been studied in normal and monoamine oxidase inhibitor pretreated mice. Additionally their interaction with 5-hydroxytryptophan (5-HTP) in producing hypoglycaemia was studied. Clomipramine, fenfluramine, fluoxetine, ORG 6582 (dl-8-chloro-11-anti-amino-benzo-(b)-bicyclo[3.3.1]nona-3, 6 alpha(10 alpha)-diene hydrochloride), ORG 6997 (dl-4-exo-amino-8-chloro-benzo-(b)-bicyclo[3.3.1]nona-2-6 alpha(10 alpha)-diene hydrochloride), MK 212 and mazindol did not modify the plasma glucose in normal mice but produced hypoglycaemia in mice pretreated with either nialamide or pargyline. Dexamphetamine did not influence plasma glucose in either normal or monoamine oxidase inhibitor pretreated mice. Each of the above drugs except ORG 6997 but including dexamphetamine augmented the hypoglycaemic effect of 5-HTP in normal mice. These responses did not appear to be mediated by insulin since none of the drugs increased the plasma immunoreactive insulin concentration or augmented the hyperinsulinaemic effect of 5-HTP. Moreover, fenfluramine, fluoxetine and ORG 6582 did not augment the hypoglycaemic action of injected insulin although such an augmentation was produced by mazindol.

Survey of North American air carriers regarding protocol for dental identification of in-flight personnel

A survey of North American air carriers regarding the protocol for dental identification of their in-flight personnel in the event of a disaster was accomplished in July 1980. Initial evaluation of this survey indicates that few air carriers have such a protocol or forensic odontology consultants. Many of the air carriers indicated the need for the development and implementation of such a protocol individualized for their company. Statistical evaluation of the survey is presented with discussion centered on the role of the forensic odontologist consulting with respective air carriers in establishing such protocols. The survey documents areas of need in such protocols.

"Hot spot" on liver scan produced by inferior vena caval obstruction

A patient suspected of having an obstruction to the inferior vena cava developed a "hot spot" in the liver when an inferior vena cavogram was performed with Tc-99-sulfur colloid. The "hot spot" was demonstrated to be the result of the collateral circulation.

Physician response to computer reminders

A computerized medical record system was designed to detect and remind the responsible clinician about clinical events that might need corrective action. These reminders significantly increased the clinician response rate (in terms of test orders and treatment changes) to the events in question. The addition of relevant medical literature citations to the reminders did not significantly change the clinician response rate as compared with that with reminders alone, nor did it stimulate the physicians to read any of the cited articles kept in an immediately available "library" of reprints.

Further studies on the effects of 5-hydroxytryptophan on plasma glucose and insulin in the mouse

The effects of 5-hydroxytryptophan on plasma concentrations of glucose and immunoreactive insulin were examined in conscious mice. Blood samples were obtained after anaesthetizing the mice lightly with ether at the desired time. Large doses of L-5-hydroxytryptophan (5HTP) (200-400 mg/kg IV) produced a dose-dependent hypoglycaemic response in fasted mice (e.g. control 5.7 +/- 0.2 mmol/l, 5HTP 400 mg/kg 2.6 +/- 0.3 mmol/l). This response was preceded by a significant elevation in the plasma immunoreactive insulin concentration (e.g. control 6 +/- 2 mU/l; 5HTP 400 mg/kg 53 +/- 7 mU/l). Induction of diabetes with alloxan (80 mg/kg IV 72 h previously) prevented the hypoglycaemic effect of 5HTP. Alloxan diabetes abolished the hyperinsulinaemic response to 100 mg/kg of 5HTP and reduced by 66% the response to 400 mg/kg of 5HTP. In alloxan diabetic mice 5HTP produced a marked hyperglycaemic response (control 17.9 +/- 2.0 mmol/l; 5HTP 100 mg/kg 36.1 +/- 2.3 mmol/l). In normal mice pre-treated with nialamide, a monoamine oxidase inhibitor, much lower doses of 5 HTP (5-10 mg/kg) were required to produce hypoglycaemia. There was no detectable elevation in the plasma insulin concentration accompanying the hypoglycaemic response to smaller doses of 5HTP in nialamide treated mice. The hyperinsulinaemic and hypoglycaemic actions of 5HTP in normal mice were prevented completely by pretreatment with benserazide, an inhibitor of aromatic amino acid decarboxylase. 5-hydroxytryptamine did not modify the plasma glucose concentration in either normal or nialamide-treated animals. It is concluded that the hypoglycaemic response to 5HTP in normal mice is mediated at least partly through an elevation in the plasma insulin concentration, although it is likely that additional mechanisms are involved.

Expression of thymidylate synthetase activity in Bacillus subtilis upon integration of a cloned gene from Escherichia coli

The gene from Escherichia coli encoding thymidylate synthetase was cloned in the plasmid pBR322. The resulting chimeric plasmid, pER2, was effective in transforming both E. coli and Bacillus subtilis to thymine prototrophy. Uncloned linear E. coli chromosomal DNA was unable to transform thymine-requiring strains of B. subtilis to thymine independence. Linearization of the chimeric plasmid, pER2, with restriction enzymes markedly diminished its ability to transform B. subtilis auxotrophs. The Thy+ transformants derived from the transformation of B. subtilis with pER2 DNA did not contain detectable extrachromosomal DNA as demonstrated by Southern hybridization patterns and centrifugation in CsCl gradients of DNA isolated from B. subtilis colonies transformed with the chimeric plasmid. We conclude that the DNA from the chimeric plasmid was integrated into the chromosome of B. subtilis, demonstrating that extensive homology is not required for the integration of foreign DNA. This is the first reported case of a gene from a Gram-negative bacterium functioning in a Gram-positive organism.

The predictive value of myocardial radioisotope scanning in animals treated with doxorubicin

Thirty-four New Zealand white rabbits were treated with doxorubicin and imaged weekly with Tc-99m pyrophosphate to define the value of abnormal myocardial images in predicting doxorubicin-induced cardiac toxicity. Increased myocardial uptake was detected in most animals on sustained treatment with doxorubicin. A greater proportion of the heart was involved with doxorubicin-related histologic changes in animals with strongly positive myocardial images than in treated animals with moderately positive or normal scans. The myocardial images returned to normal levels 2--6 wk after doxorubicin was discontinued. Five of seven rabbits that received doxorubicin after they had three moderately positive myocardial scans, died from congestive heart failure. Three rabbits whose doxorubicin was discontinued because of scan findings, survived for 6 wk or more before dying from renal failure. The three rabbits who received the highest total dose of doxorubicin died of renal failure without developing abnormal myocardial scans.

A study of irradiated bone. III. Scintigraphic and radiographic detection of radiation-induced osteosarcomas

Within 1 yr after localized irradiation of a hind limb with single (1756 rads) or fractionated (4650 rads in 3 wk) x-ray doses, radiation-induced osteosarcomas were observed in four of nine single-dose rabbits and two of 11 fractionated-dose rabbits. Tumors were observed in the proximal tibia in five cases and the distal femur in one case. In terms of production of osteoid or osseous tissue, three tumors were well differentiated, one slightly differentiated, and two (spindle-cell tumors) undifferentiated. This report summarizes the Tc-99m pyrophosphate (TcPPi) imaging and autoradiographic, radiographic, and histologic studies of these osteosarcomas. The four differentiated osteosarcomas were detected 1--2.5 mo earlier by TcPPi imaging than by radiography, whereas the two undifferentiated tumors were suspected 2 wk or 3.5 mo earlier radiographically. Autoradiograms showed TcPPi localization in bone produced by differentiated osteosarcomas, and in regions of reactive bone resorption and formation peripheral to tumors. The results support a recommendation for combined radiographic and scintigraphic techniques for the early detection of osteosarcomas.

Accidental hydrofluoric acid burns of the hand

A case report of accidental hydrofluoric acid burns that involve dermal tissue of the hand is presented. Prompt medical treatment for this accident resulted in minimal disfigurement and minimal paresthesia and disability. Protocols for essential treatment and precautions for personnel working in dental laboratories where hydrofluoric acid is used have been discussed.

The effects of levodopa on plasma glucose in two strains of rat

The effects of levodopa on plasma glucose were examined in two strains of rats. In fasted Wistar rats levodopa produced a dose-dependent hyperglycaemic response which was augmented by pretreatment with nialamide. This response in nialamide-treated rats was prevented by pretreatment with phentolamine and converted to a hypoglycaemic response. Phentolamine increased the plasma concentration of immunoreactive insulin (IRI). In phentolamine-pretreated rats levodopa produced a further marked increase in the plasma IRI concentration. It is suggested that the prevention of levodopa hyperglycaemia by phentolamine is due to the marked increase in the plasma IRI concentration produced by pretreatment with phentolamine. Moreover the fall in the plasma glucose concentration produced by levodopa in phentolamine-pretreated rats is likely to be due, at least in part, to the additional increase in the plasma IRI concentration produced by levodopa under these conditions. In contrast, in fasted Sprague-Dawley rats pretreated with nialamide, levodopa produced either no effect on plasma glucose, or in larger doses, a marked hypoglycaemic effect followed by death. This hypoglycaemic effect was accompanied by a decrease in the plasma IRI concentration.

A comparison of radiotracer and biochemical methods for the quantitation of experimental myocardial infarct weight: in vitro relationships

Anterior myocardial infarction (MI) was produced in conscious dogs to evaluate the relationships among: a) cardiac technetium-99m stannous pyrophosphate (TcPPi) accretion, b) creatine phosphokinase (CPK) depletion, and c) postmortem MI weight, infarct structure, and histology. In vitro, there was a close relationship between measured MI weight and MI weight calculated by the TcPPi accretion (r = 0.96) or CPK depletion (r = 0.93) in representative "cross-sectional" MI samples. Cardiac TcPPi accretion and CPK depletion showed a curvilinear relationship over the spectrum of tissue samples. Adjacent to infarcts, there was marked TcPPi uptake and modest CPK depletion where histology suggested ischemia without infarction. Within infarcts, microscopically visible calcium was rare in this series, suggesting little intracellular calcium accumulation, insensitivity of the von Kossa staining technique, and/or other cellular mechanisms to account for Tc-PPi uptake in this conscious dog model without reperfusion.

Mechanism of integrating foreign DNA during transformation of Bacillus subtilis

Genes encoding thymidylate synthetase from Bacillus subtilis bacteriophages were cloned in Escherichia coli. Chimeric plasmids pCD1 and pCD3 were constructed from site-specific endonuclease digests of bacteriophage phi3T DNA cloned in pMB9 in E. coli. Similar cloning techniques with bacteriophage beta22 DNA yielded chimeric plasmids pCD4, pCD5, and pCD6. Endonuclease digests of DNA from pCD1 and pCD3 propagated in E. coli or from DNA isolated from bacteriophage phi3T propagated in B. subtilis transformed B. subtilis from Thy- to Thy+. Intact DNA from bacteriophage beta22, endonuclease digests of beta22 DNA, and a chimeric plasmid (pCD5) composed only of the thybeta22 gene and pMB9 did not transform B. subtilis from Thy- to Thy+ even though pCD5 could transform Thy- E. coli to Thy+. However, if the thybeta22 fragment from pCD5 was introduced into another chimeric plasmid, pCD2, that contains a region of homology to the chromosome of B. subtilis in addition to pMB9, transformation of Thy- clones of B. subtilis was possible. Furthermore, Southern hybridization analyses of the digests of chromosomal DNA from the Thy+ transformants established that the entire chimeric plasmid was incorporated into the chromosome of B. subtilis. Treatment of these plasmids with site-specific endonucleases abolished transformation. These results indicated that the entire chimeric plasmid can be incorporated into the chromosome of B. subtilis by a Campbell-like model. Therefore, an additional mechanism for transformation exists whereby plasmids can be integrated if sufficient chromosomal homology is maintained.

Biochemical and genetic properties of site-specific restriction endonucleases in Bacillus globigii

Bacillus globigii contains two site-specific endonucleases, BPGLI AND BglI. A rapid technique for selection of mutants deficient in each of these enzymes was developed using sensitivity to infection by bacteriophage SP50 as an indication of the levels of enzyme. Mutants defective in BglI, BglII, and both BglI and BglII retained the wild-type modification phenotype. Genetic and biochemical studies have established that these enzymes are involved in restriction in vivo. Simplified purification procedures for BglI and BglII using these mutants are described.