Preclinical efficacy and pharmacokinetics of an RNA-encoded T cell-engaging bispecific antibody targeting human claudin 6

We present the preclinical pharmacology of BNT142, a lipid nanoparticle (LNP)-formulated RNA (RNA-LNP) encoding a T cell-engaging bispecific antibody that monovalently binds the T cell marker CD3 and bivalently binds claudin 6 (CLDN6), an oncofetal antigen that is absent from normal adult tissue but expressed on various solid tumors. Upon BNT142 RNA-LNP delivery in cell culture, mice, and cynomolgus monkeys, RNA is translated, followed by self-assembly into and secretion of the functional bispecific antibody RiboMab02.1. In vitro, RiboMab02.1 mediated CLDN6 target cell-specific activation and proliferation of T cells, and potent target cell killing. In mice and cynomolgus monkeys, intravenously administered BNT142 RNA-LNP maintained therapeutic serum concentrations of the encoded antibody. Concentrations of RNA-encoded RiboMab02.1 were maintained longer in circulation in mice than concentrations of directly injected, sequence-identical protein. Weekly injections of mice with BNT142 RNA-LNP in the 0.1- to 1-μg dose range were sufficient to eliminate CLDN6-positive subcutaneous human xenograft tumors and increase survival over controls. Tumor regression was associated with an influx of T cells and depletion of CLDN6-positive cells. BNT142 induced only transient and low cytokine production in CLDN6-positive tumor-bearing mice humanized with peripheral blood mononuclear cells (PBMCs). No signs of adverse effects from BNT142 RNA-LNP administration were observed in mice or cynomolgus monkeys. On the basis of these and other findings, a phase 1/2 first-in-human clinical trial has been initiated to assess the safety and preliminary efficacy of BNT142 RNA-LNP in patients with CLDN6-positive advanced solid tumors (NCT05262530).

Site-Specific Conjugation Strategy for Dual Antibody-Drug Conjugates Using Aerobic Formylglycine-Generating Enzymes

Multiple, site-specific protein conjugation is increasingly attractive for the generation of antibody-drug conjugates (ADCs). As it is important to control the number and position of cargoes in an ADC, position-selective generation of reactive sites in the protein of interest is required. Formylglycine (FGly) residues are generated by enzymatic conversion of cysteine residues embedded in a certain amino acid sequence motif with a formylglycine-generating enzyme (FGE). The addition of copper ions increases FGE activity leading to the conversion of cysteines within less readily accepted sequences. With this tuned enzyme activity, it is possible to address two different recognition sequences using two aerobic formylglycine-generating enzymes. We demonstrate an improved and facile strategy for the functionalization of a DARPin (designed ankyrin repeat protein) and the single-chain antibody scFv425-Fc, both directed against the epidermal growth factor receptor (EGFR). The single-chain antibody was conjugated with monomethyl auristatin E (MMAE) and carboxyfluorescein (CF) and successfully tested for receptor binding, internalization, and cytotoxicity in cell culture, respectively.

Identification and regulation of the gastric H+/K+-ATPase in the rat heart

Previous reports indicate that H+/K+-adenosine triphosphatase (ATPase) might be expressed in the heart.

AIMS

The objectives of the present study were to explore the presence of H+/K+-ATPase protein and gene expression in the rat heart and to investigate whether the enzyme could contribute to potassium transport across the sarcolemma.

METHODS AND RESULTS

We performed reverse transcription-polymerase chain reaction (RT-PCR) on mRNA from myocardium and isolated cardiomyocytes using primers specific for the gastric H+/K+-ATPase alpha-subunit. The PCR products were sequenced and the predicted gastric H+/K+-ATPase sequence was verified. Western blots from myocardium detected a 34-kDa band and a 94-kDa band, indicating the beta-subunit and alpha-subunit of the gastric H+/K+-ATPase, respectively. Immunocytochemistry detected significant immunoreactivity of the beta-subunit in cardiomyocytes. H+/K+-ATPase-dependent potassium transport was assessed by 86Rb+-uptake in isolated cardiomyocytes. Both ouabain and the selective H+/K+-ATPase inhibitor Schering 28080 reduced 86Rb+-uptake at maximum specific inhibition, by 70 and 25%, respectively; the effects were additive. Competitive RT-PCR analysis indicated a significant upregulation of the myocardial H+/K+-ATPase in heart failure after myocardial infarction.

CONCLUSION

The gastric isoform of H+/K+-ATPase is expressed in rat cardiac myocytes, both at transcript and protein levels. Functional studies indicate that the enzyme could contribute to potassium and pHi regulation in cardiomyocytes.

Cardiomyocyte contractility and calcium handling partially recover after early deterioration during post-infarction failure in rat

The aim of the study was to determine whether progression of heart failure is associated with deterioration of cardiomyocyte function. Cell dimensions, contractility and calcium transients were measured in cardiomyocytes isolated from the left ventricle of female Wistar rats 1, 4, and 13 weeks after coronary artery ligation or sham-operation. Relative cardiomyocyte shortening decreased from 26% in controls to 11% 1 week after myocardial infarction and recovered to 18 and 20% after 4 and 13 weeks, respectively. Diastolic and systolic calcium concentrations increased markedly 1 week after myocardial infarction with subsequent reduction after 4 and 13 weeks. Time to 50% relaxation was prolonged by 31% after 1 week and 20% after 4 and 13 weeks with corresponding changes in diastolic calcium clearance. Cardiomyocyte length increased by 6, 24, and 26% after 1, 4 and 13 weeks, respectively, whereas myocyte width increased by 4, 11 and 27%. Cardiomyocytes adjacent to the infarct hypertrophied more and initially had more markedly impaired function than in the remote area. Left ventricular diastolic diameter assessed by echocardiography increased by 47, 66 and 84% after 1, 4 and 13 weeks, respectively, and systolic diameter increased by 120, 162 and 194%. Left ventricular end-diastolic pressure increased from 6 mmHg to 24, 25 and 36 mmHg. Whereas initial deterioration of cardiac function is associated with reduced cardiomyocyte contractile function, chronic heart failure progression is not accompanied by further impairment of intrinsic cardiomyocyte contractility in this model. Cardiomyocyte hypertrophy and dysfunction are more marked adjacent to the infarction.

Increased contractility and calcium sensitivity in cardiac myocytes isolated from endurance trained rats

OBJECTIVE

Regular exercise enhances cardiac function and modulates myocyte growth in healthy individuals. The purpose of the present study was to assess contractile function and expression of selected genes associated with intracellular Ca2+ regulation after intensity controlled aerobic endurance training in the rat.

METHODS

Female Sprague-Dawley rats were randomly assigned to sedentary control (SED) or treadmill running (TR) 2 h per day, 5 days per week for 2, 4 or 13 weeks. Rats ran 8-min intervals at 85-90% of VO2max separated by 2 min at 50-60%. Myocyte length, intracellular Ca2+ (Fura-2), and intracellular pH (BCECF) were measured in dissociated cells in response to electrical stimulation at a range of stimulation rates.

RESULTS

The increase in VO2max plateaued after 6-8 weeks, 60% above SED. After 13 weeks, left and right ventricular weights were 39 and 36% higher than in SED. Left ventricular myocytes were 13% longer, whereas width remained unchanged. After 4 weeks training, myocyte contractility was approximately 20% higher in TR. Peak systolic intracellular Ca2+ and time for the decay from systole were 20-35 and 12-17% lower, respectively. These results suggest that increased myofilament Ca2+ sensitivity is the dominant effect responsible for enhanced myocyte contractility in TR. Intracellular pH progressively decreased as stimulation frequency was increased in the SED group. This decrease was markedly attenuated in TR and the intracellular pH was significantly higher in the TR group at a stimulation rate of 5-10 Hz. This effect may contribute to the increased contractility observed at the higher stimulation frequencies in TR. A higher intrinsic myofilament Ca2+ sensitivity was observed in permeabilised myocytes from the TR group under conditions of constant pH and [Ca2+]. Western blot analysis indicated 21 and 46% higher myocardial SERCA-2 and phospholamban, but unaltered Na+/Ca(2+)-exchanger levels. Competitive RT-PCR revealed that TR significantly increased Na+/H(+)-exchanger mRNA.

CONCLUSION

Intensity controlled interval training increases cardiomyocyte contractility. Higher myofilament Ca(2+)-sensitivity, and enhanced Ca(2+)-handling and pH-regulation are putative mechanisms. Our results suggest that physical exercise induces adaptive hypertrophy in cardiac myocytes with improved contractile function.

Demonstration of Chlamydia pneumoniae in the adenoid from children with and without secretory otitis media using immunohistochemistry and PCR

Chlamydia pneumoniae has been found in patients with middle ear inflammation. The adenoid, which has a central role in the development of secretory otitis media (SOM), may act as a reservoir for bacteria causing ear infection. Adenoid tissue was examined for the presence of C. pneumoniae. Twenty children undergoing adenoidectomy because of hyperplastic adenoids, 10 with SOM and 10 without SOM, were examined with nasopharyngeal swabs for routine bacteriological culture, serology for C. pneumoniae and throat swabs for C. pneumoniae PCR. The removed tissues were analyzed for C. pneumoniae using immunohistochemical (IHC) analysis and PCR. In the group of children with SOM samples were also taken from the middle ear fluid for routine bacteriological culture and PCR for C. pneumoniae. C. pneumoniae was found in the adenoid by PCR in 3 cases from each group and from all 20 children by IHC. Four children in each group had increased levels of specific antibodies to C. pneumoniae. Two children with SOM had high antibody titers and a positive PCR from a throat swab. Two children were PCR-positive for C. pneumoniae in fluid from the middle ear. The significance of these findings is not yet clear.

Protective effects of repetitive injections of radiographic contrast media on the subsequent tolerance to ischemia in the isolated rat heart

PURPOSE

Despite detailed knowledge of the effects of X-ray contrast media on cardiac function, no studies have examined the effect of contrast media injections on the subsequent tolerance to ischemia in the heart.

METHODS

Isolated perfused rat hearts were exposed to repetitive injections of iohexol, iodixanol, or ioxaglate before 30 min of global ischemia and 120 min of reperfusion. These groups were compared with control (no pretreatment) and ischemic preconditioning known to reduce infarct size. Physiologic variables and infarct size were measured

RESULTS

Pretreatment with iodixanol reduced infarct size significantly compared with control and thus afforded protection against ischemia. Injections with iohexol and ioxaglate reduced infarct size, although not significantly, compared with control.

CONCLUSION

Pretreatment of the isolated rat heart with commonly used contrast media enhances the cardiac tolerance to subsequent ischemia. The mechanism behind this protective effect could not be determined, but could involve stretching of the heart and/or generation of nitric oxide.

[Clinical skills among interns]

BACKGROUND

Previous reports have demonstrated variable and partly insufficient skills levels in common practical procedures among interns after internship in hospital. The aim of the present study was to examine the development in interns' skills levels in practical procedures in relation to their gender, medical school, hospital and supervision.

MATERIAL AND METHODS

Between July 1996 and July 1999 all interns in Norway were asked to indicate their skills level in 88 practical clinical procedures before and after hospital internship. Of the 599 interns included, 472 replied (79%).

RESULTS

Males reported significant higher skills levels than females. After internship, no differences between interns graduated from the four universities were observed. Our study shows that the hospital internship is an important part of the medical education. An overall improvement was found in all interns. Interns whose skills levels were low before internship, had the best improvement.

INTERPRETATION

The finding of a variable skills level before and a variable development during internship indicates that teaching in practical procedures is unstructured and inadequate. A consensus on the skills to be acquired and on what level is needed. Improvements are also needed in the quality of supervision.

Tolerance and efficacy of interfering alpha-streptococci in recurrence of streptococcal pharyngotonsillitis: a placebo-controlled study

A total of 342 patients with clinical signs of tonsillitis and suspected group A beta-haemolytic streptococci (GAS) aetiology, verified with rapid test and GAS culture, were enrolled in a randomized, placebo-controlled, double-blind, multicentre study. They received antibiotic treatment for 10 days, followed by 10 days of alpha-streptococcal or placebo spray treatment in the ratio of 2 : 1. Pharyngeal status, throat culture and adverse events were investigated up to 75 days after treatment. The frequency of bacteriologically verified clinical recurrence was 13% in the alpha-streptococcal group and 15% in the placebo group at the follow-up on day 22. The corresponding figures at the last valid visit after 45-75 days were 19% and 30%, respectively, a statistically significant difference (p = 0.037). Furthermore, at the last valid visit 5% of subjects in the alpha-streptococcal and 12% in the placebo group were healthy carriers, bacteriological treatment failures, of GAS (p = 0.029). Treatment with alpha-streptococci and placebo spray were equally well tolerated. Thus, re-colonization with alpha-streptococci seem to hinder late recurrences of GAS pharyngotonsillitis.

Hyperosmotic perfusion of the beating rat heart and the role of the Na+/K+/2Cl- co-transporter and the Na+/H+ exchanger

The aim of the present study was to investigate the role of the Na+/K+/2Cl- co-transporter and the Na+/H+ exchanger on contractile function and electrolyte regulation during hyperosmotic perfusion of the heart. Langendorff perfused rat hearts were subjected to hyperosmolal perfusion in 10-min intervals. Perfusates were made hyperosmotic by adding mannitol to the buffer (370, 450 and 600 mOsmol/kg H2O). Cardiac contractile function was monitored with a balloon in the left ventricle (LV) coupled to a pressure transducer. Cardiac effluent was sampled repeatedly throughout and after hyperosmotic perfusion and analysed for content of Na+, K+, and Cl-. All three hyperosmotic perfusates initially reduced LV developed pressure (LVDP), but for 370 and 450 mOsmol/kg H2O, LVDP recovered to baseline within 4 min of perfusion. With 600 mOsmol/kg H2O, LVDP recovered slowly and was 50% below baseline after 10 min of hyperosmotic perfusion. Inhibition of the Na+/H+ exchanger with 5-(N-ethyl-N-isopropyl) amiloride (EIPA) and 3-methylsulfonyl-4-piperidinobenzoyl-guanidine methanesulfonate (HOE 694) abolished the recovery of LVDP to the 600 mOsmol/kg H2O perfusate, whereas inhibition of the Na+/K+/2Cl- co-transporter had no impact on LVDP. Potassium was taken up by the heart during hyperosmotic perfusion and this uptake was significantly reduced with inhibition of the Na+/H+ exchanger. Intracellular pH was assessed with 31p magnetic resonance spectroscopy and hyperosmolality induced a significant alkalosis that was dependent upon the Na+/H+ exchanger. The rat heart responds to moderate elevations in osmolality with a transient reduction in contractile function, whereas an elevation of 300 mOsmol/kg H2O persistently reduces contractile function. The Na+/H+ exchanger, but not the Na+/K+/2Cl- co-transporter, is of importance in contractile recovery and electrolyte regulation during hyperosmotic perfusion in the rat heart.

Hyperosmotic pretreatment reduces infarct size in the rat heart

Preconditioning of the heart can be achieved by an ischemia/reperfusion stimulus, but also by stretching of the heart by an acute volume overload. Since manipulations of the extracellular osmolality affects cell size, we hypothesized that hyperosmotic pretreatment of the isolated perfused rat heart could reduce infarct size following regional ischemia (RI). Langendorff perfused rat hearts were subjected to 30 min RI by ligature of the main branch of the left coronary artery followed by 120 min reperfusion (control group). Ischemic preconditioning (IP-5') was achieved by 5 min total global ischemia and 5 min reperfusion prior to RI. Hyperosmotic pretreatment was accomplished by perfusion with a hyperosmotic buffer (600 mOsm/kg H2O by adding mannitol) for 1 min, 2 min or 5 min. At the end of the experiments, the hearts were cut into 2 mm slices, incubated with triphenyltetrazoliumchloride before scanning and computerized for estimation of infarct size. The average infarct size (as percentage of area at risk) in the control group was 42% and was significantly reduced to 16% by ischemic preconditioning and to 17% by 2 min hyperosmotic pretreatment. Neither 1 min nor 5 min hyperosmotic pretreatment reduced infarct size as compared to the controls. The infarct reducing effect of 2 min hyperosmotic pretreatment was not blunted by inhibition of protein kinase C (chelerytrine chloride), the Na+/H+-exchanger (HOE 694) or stretch-activated anion channels (gadolinium chloride). The results indicate that short-lasting hyperosmotic perturbations of the extracellular environment may precondition the heart to a subsequent ischemic insult.

[Self-assessment of clinical skills among medical trainees when entering internship during the spring seasons 1998]

The aim of this study is to identify medical trainees' level of self-reported clinical skills when entering internship. A questionnaire was sent to 124 trainees, who were about to enter their internship. The questionnaire included 88 questions on clinical skills, asking the trainees to rate their level of mastership on a Visual Analogue Scale from zero to ten, 0 = not mastering and 10 = mastering. In total one hundred (81%) returned the questionnaire. There is considerable variation in the self reported acquisition of clinical skills in many of the procedures. In some basic procedures most trainees showed a rather high level of mastership, above 7.5, but in other basic procedures about half of the candidates report a level of mastership below 5.0. A more thorough specification of objectives for practical skills would make it easier to plan an effective and efficient training during internship.

Effect of magnesium infusion on bleeding time in healthy male volunteers

Intravenous magnesium has proved to be valuable in the treatment of cardiac arrhythmias and eclampsia, but the specific mode of action is not established. In this study the effect of magnesium sulphate (MgSO4) infusion on bleeding time and endogenous prostacyclin (PGI2) production in healthy male volunteers was investigated. Thirty-five males (age 18-30 years) randomized in a double-blind, placebo-controlled, cross-over study were investigated. MgSO4 was given as a bolus (8 mmol, 12 min) followed by continuous infusion (8 mmol in 108 ml saline, 120 min). Control was equal volumes of physiological saline. Heart rate, blood pressure and bleeding time (according to Ivy) were recorded as well as blood concentrations of magnesium and creatinine. Urine PGI2 was analysed as the stable metabolite 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha). Treatment with MgSO4 did not affect bleeding time (MgSO4; 8.4+/-3.5 vs. control 8.0+/-2.7 min) nor the production of PGI2 (MgSO4; 1.2 microg 6-keto-PGF1alpha/g creatinine vs. control; 1.1 microg 6-keto-PGF1alpha/g creatinine). Intravenous infusion of MgSO4 does not affect the PGI2/platelet axis in healthy male volunteers. Studies in patients with endothelium dysfunction and/or concomitant drug therapy are required before the anti-thrombogenic effect of MgSO4 in vivo is discarded.

[Self-reported skills in practical procedures among young physicians]

There is at present no consensus as to which clinical procedures a student should be able to perform after graduation. The present study was undertaken to evaluate the self-reported skills level in practical procedures among graduates from the medical schools in Norway. A questionnaire was mailed to all students who entered internship between July 1996 and January 1998. They were asked to indicate on a visual-analogue scale the level of skill he or she had acquired in 88 practical clinical procedures. 519 of 621 (84%) graduates replied; 89% started internship immediately after graduation. Graduates from Tromsø reported significantly better skills than graduates from Oslo and Bergen. There was considerable variation within and between the universities with respect to several procedures. Overall, men reported a significantly better skills level than their female colleges. The present study demonstrates that the skills level in several procedures vary considerably between candidates graduating from different Norwegian universities after undergraduate medical education. For some procedures the skills level is, in our opinion, disquietingly low. The results of this survey indicate that teaching of clinical procedures in medical school is often random and of inferior quality. There is a need for a systematic approach and a national consensus on the clinical procedures to be acquired and the levels of skills to be attained.

Cardiac contractile function and electrolyte regulation during hyperosmolal stress: an experimental study in the isolated rabbit heart

Perturbations of the extracellular osmotic environment leads to cell volume changes. The aim of the present study was to evaluate the effects of hyperosmolality on cardiac contractile function and in particular the role of ionic mechanisms anticipated to be operative during hyperosmolal exposure. Paced rabbit hearts were perfused in the Langendorff mode and were exposed to 330, 370, 410, 450 and 600 mOsm kg-1 in 10 min. intervals intervened by 15 min. isosmolal buffer perfusion (by adding mannitol). Thereafter, 370 and 600 mOsm kg-1 perfusates were chosen for investigation of the effects of inhibition of the Na-K-2Cl co-transporter (bumetanide 1 microM and 10 microM), the Na+/H+ exchanger (5-(N-ethyl-N-isopropyl amiloride (EIPA) 100 nM) and the Na+/K(+)-ATPase (ouabain 50 nM). After a rapid and transient decrease in left ventricular developed pressure, all perfusates up to 450 mOsm kg-1 increased LVDP. The 600 mOsm kg-1 perfusate initially reduced LVDP by 50%, but LVDP increased to 85% of initial value at the end of the 10 min. perfusion. EIPA attenuated the recovery of LVDP during perfusion with 600 mOsm kg-1, whereas bumetanide did not affect cardiac contractile function. A net uptake of potassium was observed during hyperosmolal perfusion. Inhibition of the Na+/H+ exchanger resulted in a continued release of cardiac water throughout hyperosmolal perfusion. Isolated perfused rabbit hearts tolerate considerable elevations in perfusate osmolality. Our results suggest that the Na+/H+ antiporter is activated on hyperosmolal exposure with a secondary activation of the Na+/K(+)-ATPase. Since inhibition with bumetanide did not affect contractility or electrolyte movements, the Na-K-2Cl co-transporter does not seem to play an important role in cardiac response to hyperosmolality in rabbits.

Association of Chlamydia pneumoniae with otitis media in children

Chlamydia pneumoniae is a common cause of acute and persistent respiratory tract infections. The prevalence of C. pneumoniae was studied using the polymerase chain reaction (PCR) in throat swabs from 85 consecutive children with respiratory tract infections and 86 healthy children. In retrospect, it became evident that this study was conducted in the midst of a local C. pneumoniae epidemic. 38 (45%) of the sick children and 5 (5.7%) of the healthy children were positive for C. pneumoniae by PCR. 26 of the sick children (mean age 6.4 years) were found to have otitis media either at the time of examination or shortly thereafter. Six of 9 children with acute otitis media were PCR positive for C. pneumoniae and 7 of the 9 had specific antibody responses indicating active infection. 10 of 17 children diagnosed as having otitis media with effusion were found to be positive for C. pneumoniae by PCR. Seven children had or developed persistent otitis media with effusion. Chlamydia pneumoniae was demonstrated by PCR from the middle ear fluid in 1 of the children. The results obtained from this study indicate that C. pneumoniae may be involved in the aetiology of otitis media.

Demonstration of Chlamydia pneumoniae in patients with chronic pharyngitis

12 patients with longstanding throat symptoms, who were also positive by PCR (polymerase chain reaction) for Chlamydia pneumoniae were selected for a longitudinal study to determine whether C. pneumoniae is an aetiological agent for chronic pharyngitis. Specimens for culture and PCR detection of C. pneumoniae were taken from the retropharyngeal wall and blood specimens were taken for serology. Biopsies were taken from the mucosal membrane of the retropharyngeal wall for histological and immunohistochemical studies. C. pneumoniae was cultured from 4 cases. 10 patients had specific humoral antibodies to C. pneumoniae and 9 had high and increasing specific antibody titres to C. pneumoniae suggesting ongoing infection. The organism was demonstrated in the tissue from the retropharyngeal mucosal membrane by immunohistochemistry in 9 patients. The findings suggest that C. pneumoniae may be an aetiological agent for chronic pharyngitis.

Recurrence rate of streptococcal pharyngitis related to hygienic measures

OBJECTIVE

To test the hypothesis that treatment failures of streptococcal pharyngotonsillitis may be caused by reinfection by the patients' own streptococci remaining on a toothbrush or in the bedclothes.

DESIGN

To elucidate the role of streptococcal contamination of the environment, hygienic measures regarding change of toothbrush and bed linen and washing of toys were given to half of the patients/families. Throat specimens were taken from all the patients before treatment with phenoxymethylpenicillin for 5 days, and the patients were followed-up for 1 month. At a home visit after 6-10 days, throat specimens were taken from the patients and all permanent residents of the home. Environmental samples were taken from pillowcases, floors, toothbrushes, dummies, and toys.

SETTING

Six health care centres.

SUBJECTS

114 patients of all ages suffering from group A streptococcal pharyngotonsillitis, and 289 family members.

MEASUREMENTS AND MAIN RESULTS

54 patients/families received hygiene instructions. The total number of recurrences was 40 (35%). There was no difference in treatment failure rate between patients/families that had taken or not taken hygienic measures.

CONCLUSIONS

Hygienic measures have no decisive influence on the risk of recurrence of streptococcal pharyngotonsillitis.

Group A streptococci in household pets' eyes--a source of infection in humans?

Household pets were examined when we carried out an investigation to study intrafamilial spread of group A streptococcal infection. Cultures were taken from 114 index cases, and 61 pets. Group A streptococci were demonstrated in eye secretions from 2 pets. Transmission of group A streptococci from humans to pets and vice versa can probably occur, but is uncommon.

Hypochondroplastic dwarfism in the Irish setter

Two test matings in the irish setter were performed, and genetic, clinical, morphometric, radiographic, bone histological and plasma and urine biochemical features of dwarfism were studied. All offspring were phenotypically normal at birth and weaning, but at the age of 2.5 to 4 months the longitudinal growth of the spine and leg bones was retarded in the dwarfs compared with the normal littermates. Most dwarfs performed well, even in the field. Radiographic and histological evaluations revealed a hypochondroplasia. A morphometric diagnostic method for Irish setter dwarfism was developed. A single autosomal recessive mode of inheritance was verified.

Influence of culture time on the frequency and contents of human lymphocyte micronuclei with and without cytochalasin B

The effects of culture time (52, 64 and 76 h) and cytochalasin B (Cyt-B, 3 micrograms/ml) on the frequency of micronuclei (MN) harbouring whole chromosomes and acentric fragments was investigated in purified lymphocyte cultures of five nonsmoking male donors aged 41-50 years. Centromere-positive (C+) MN were identified by fluorescence in situ hybridization, using an alphoid DNA oligomer probe (SO-alpha AllCen) hybridizing to all human centromeres. For each culture time, 2000 cells and 60 MN were scored per donor, both with and without Cyt-B, making a total of 60,000 cells and 1800 MN. The frequency of MN and the proportion of C+ MN were higher at 64 h and 76 h than at 52 h, irrespective of Cyt-B. The culture time-dependent increase in MN frequency was mainly due to C+ MN which were about 1.5-times more frequent at 64 h and 72 h than at 52 h. The frequencies of C+ MN, expressed per 1000 nuclei, were similar with and without Cyt-B, although the prevalence of C+ MN was consistently about 10 percent units higher in the former type of culture. This effect was due to a decreased frequency of centromere-negative (C-) MN in the binucleate cells, possibly reflecting, e.g. increased inclusion of acentric chromosomal fragments within the main nuclei of such cells, enhanced expulsion of C- MN, or selection against binucleate cells carrying such MN. In conclusion, the present findings indicate that MN harbouring whole chromosomes become more frequent at long culture times with and without Cyt-B and that Cyt-B-induced binucleate cells show a reduced frequency of MN containing acentric fragments. Due to the high background of whole-chromosome-containing MN (mean C+ MN proportions ranged from 42.3% to 62.7%), it may be recommended that centromeric fluorescence in situ hybridization is routinely applied when lymphocyte MN are used as a biomarker of human exposure to clastogens.

Prevalence of Chlamydia pneumoniae in healthy children and in children with respiratory tract infections

BACKGROUND

Chlamydia pneumoniae causes respiratory tract infections in adults, but little is known about its significance for acute or persistent respiratory tract infections in children.

METHODS

We studied the prevalence of C. pneumoniae by polymerase chain reaction in children younger than the age of 11: 85 consecutive children with respiratory tract infections; and 93 children presumed to be healthy. Throat swabs for PCR analysis were taken from all children, and serology was done for 54 of the 85 sick children and from all but one of the presumed healthy children positive for C. pneumoniae by PCR.

RESULTS

PCR was positive in 38 (45%) of the sick children and in 5 (5.7%) of the healthy children. All but 2 of 19 sick children with serologic findings suggesting recent or ongoing infection with C. pneumoniae were positive by PCR. Most children positive for C. pneumoniae by PCR had upper respiratory tract infections. Four children had recurrent respiratory tract infections and otitis media with effusion treated by tubal insertion.

CONCLUSION

The findings suggest that C. pneumoniae is common among children with respiratory tract infections.

Skills of pre-registration house officers: gender differences reported in Norway

During training pre-registration house officers should acquire skills, practical clinical procedures, and good clinical judgement, in order to be able to practice on their own. This is not always the case (Flaatten et al. 1987). Ten years ago the Norwegian Health Authorities issued a regulation regarding the content of hospital training (6 months internal medicine and surgery, respectively). A number of practical skills to be learned were listed. As part of an assessment of the quality of the internship, a study was carried out into what extent the pre-registration house officers had acquired these clinical skills.

Biophysical factors and contractile function during coronary bolus perfusion: an experimental study in the isolated guinea pig heart

RATIONALE AND OBJECTIVES

The purpose of this study was to evaluate the role of biophysical factors (viscosity, temperature, osmalality, perfusion pressure, and ionic washout) on cardiac contractility during coronary bolus perfusions.

METHODS

Guinea pig hearts were perfused in the osmolality mode at constant and high flow (30 mL/min) and were subjected to boluses (injected in 1-8 seconds) of purely nonionic media: mannitol and iohexol (in hyposmolal, isosmolal, and twice isosmolal forms) and iodixanol (in a hyposmolal form).

RESULTS

All contrast media elicited a dose-dependent increase in aortic pressure and contractile variables that was attenuated by an increased osmolality. Elevation of aortic pressure was followed by an increase in left ventricular systolic pressure and, with iodixamol and iohexol, a subsequent elevation of left ventricular end-diastolic pressure. Moderate hypothermic solutions (29 degrees C) did not alter the responses. The ionic washout profile was the same for the three substances, as were the individual washout profiles for sodium, potassium, chloride, magnesium, and calcium.

CONCLUSION

An increase in osmolality attenuates the increased contractility induced by a purely nonionic medium. A viscosity-induced rise in perfusion pressure may increase contractility. A moderate reduction in bolus temperature does not alter the contractile responses. The ionic washout profile is the same for the main cardioactive electrolytes.

Influence of GSTM1 and GSTT1 polymorphisms on the frequency of chromosome aberrations in lymphocytes of smokers and pesticide-exposed greenhouse workers

The influence of polymorphic glutathione S-transferases mu (GSTM1) and theta (GSTT1) on the rate of chromosome aberrations (CA) in peripheral lymphocytes of 30 pesticide-exposed floriculturists and 32 control subjects was studied. Pesticide exposure was not associated with elevated frequencies of CA. Among cigarette smokers, a statistically significant (p = 0.026) increase in baseline CA frequencies was observed in subjects with a homozygous deletion of the GSTM1 gene (GSTM1 null, n = 36) in comparison with those having at least one copy of the gene (GSTM1 positive, n = 26). This effect was mainly due to an excess of chromatid-type aberrations (p = 0.006). In addition, the few individuals (n = 5) deficient for both GSTM1 and GSTT1 showed significantly higher (p = 0.012) CA counts than GSTM1 positive GSTT1 nulls. Despite the limited number of subjects genotyped, the results seem to indicate an association between smoking induced CA frequencies and GSTM1 polymorphism, and a possible interaction between the GSTM1 and GSTT1 genotypes. The findings may be explained by the reduced detoxification capacity of GSTM1 null and GSTT1 null individuals.

The role of household contacts in the transmission of group A streptococci

The intrafamilial spread and recurrence of group A beta-haemolytic streptococci (GAS) infections was investigated. The evaluation was based on 114 patients and their families treated with penicillin for 5 days and followed for 1 month. GAS of the same T-type as that of the isolate from the index case were found in other family members in 33% of the families. Genetic finger-printing using RFLP was performed on 33 of the isolates. The mothers dominated among the index cases, 40 patients experienced recurrences, 27 of them were clinical 28 recurrences occurred within 10 days after the end of treatment. Of 20 T-typed patients with early clinical treatment failures, infected family members were detected in 16 families (p < 0.001). In 19% of the patients GAS could be isolated from the nose. These patients had more ill family members than did other patients. An extensive intrafamilial streptococcal spread was found. Most recurrences of GAS pharyngotonsillitis after penicillin treatment are probably due to "ping pong" infection from family members.

Sudden infant death syndrome: postmortem findings of nicotine and cotinine in pericardial fluid of infants in relation to morphological changes and position at death

Parental smoking is considered to be an important risk factor for the sudden infant death syndrome (SIDS). We studied the concentrations of nicotine and cotinine in the pericardial fluid of SIDS and non-SIDS victims, with particular emphasis on the relationship to body position at the time of death and organ pathology. Pericardial fluid was collected during a forensic postmortem examination of 85 nonselected infants, under the age of 1 year, who died from SIDS (n = 67) and non-SIDS (n = 18) in the period from 1988 to 1994. There was no significant difference in the pericardial concentration of nicotine and cotinine between SIDS and non-SIDS victims. However, in contrast to non-SIDS victims, about 25% of the infants in the SIDS group had cotinine concentrations exceeding 30 ng/mL, indicating tobacco exposure prior to death. High concentrations of cotinine were found in infants with focal necrosis and inflammatory changes in the myocardium and the liver. Further, a relationship was found between high nicotine concentration and otitis media and also with death while cosleeping.

Mast cells in human coronary arteries; is there any correlation with luminal narrowing?

Histamine in the human coronary arteries is harboured in mast cells and possibly in a non-mast cell store. Upon histamine exposure atherosclerotic coronary arteries react differently than normal coronary arteries, and histamine has been proposed to provoke vasospasms, ischaemia and sudden cardiac death. Previous reports have indicated a correlation between the mast cell density and the histamine content on the one hand and the degree of atherosclerosis on the other hand. Since previous reports applied visual assessment of the luminal narrowing only, we reexamined these results utilising planimetric methods. The study was accomplished by examining coronary arteries from autopsy cases (50-70 years, N = 29) with a diagnosis of sudden death, myocardial infarction or a non-cardiac cause. The mast cell density was calculated as the ratio between the mast cell count and the adventitial area as seen by light microscopy, and was compared to the degree of luminal narrowing. We were not able to find any correlation between the mast cell density and the luminal narrowing. The myocardial infarction group had the most severe degree of luminal narrowing, but there was no significant difference in mast cell density between the groups. We therefore question the previous notion that there is a correlation between the adventitial mast cell density in the coronary arteries and the luminal narrowing. Earlier reports may have been biased by visual assessment and by erroneously treating several measurements from the same person as independent samples.

In vivo cytogenetic damage revealed by FISH analysis of micronuclei in uncultured human T lymphocytes

FISH analysis of micronuclei in uncultured human T lymphocytes provides a convenient new possibility to assess structural and numerical chromosome damage in vivo. In women. T-cell micronuclei mostly contained whole chromosomes (71.6%), especially the X chromosome (28.5%). Cell culture (72 h) enhanced the frequency of micronuclei harboring acentric fragments 2.9 fold and the X chromosome 1.5 fold. X-chromosome-positive micronuclei were particularly prevalent (42.0%) in binucleate cells produced by cytochalasin B, a cytokinesis inhibitor used to identify cells that have divided in vitro. This was explained by a decrease in autosome-containing and an increase in X-positive micronuclei.

Persistent Chlamydia pneumoniae infection in a Swedish family

Chlamydia pneumoniae, an etiological agent for respiratory tract infection, was found as a cause of persistent infection in a family group. During the observation period of 2 1/2 years, serology and polymerase chain reaction for C. pneumoniae demonstrated a failure to eradicate the organism, despite several prolonged courses of antibiotics known to be effective against chlamydia species.

Cytogenetic monitoring of occupational exposure to pesticides: characterization of GSTM1, GSTT1, and NAT2 genotypes

Occupational exposure of floriculturists is characterized by alternating periods of intense pesticide spraying and reduced or no activity. Induction of sister chromatid exchanges (SCE), structural chromosome aberrations (CA) and micronuclei (MN) was investigated in peripheral lymphocytes of a group of 23 Italian floriculturists and 22 matched controls. Blood sampling was performed during and one month after the end of intensive pesticide treatments, in order to cover a period of high and low exposure, respectively. Each donor was genotyped for glutathione S-transferase M1 (GSTM1), T1 (GSTT1), and N-acetyltransferase 2 (NAT2), three polymorphic genes involved in xenobiotic metabolism, to assess their potential role in individual genotoxic response to the pesticide exposure. No effect of the pesticide exposure on the cytogenetic parameters were detected. Smoking, however, was found to increase SCE levels. The only significant influence of phenotype composition on cytogenetic response was an increase in SCE levels in the GSTT1 positive individuals compared with the GSTT1 nulls (P=0.02). This finding was, however, based on only four GSTT1 null donors (n=41 for GSTT1 positive donors). In addition, a possible interaction was observed between smoking and GSTM1 genotype in the CA assay, GSTM1 null smokers, earlier reported to have an elevated risk for lung cancer, showing higher CA frequencies than GSTM1 positive smokers.

[Is the training of interns in practical clinical skills adequate?]

In Norway the preregistration internship consists of 12 months service in hospitals followed by 6 months in general practice. This survey assessed to what extent the intended practical skills had been aquired during the hospital service. A questionnaire was sent to all preregistration house officers who had recently completed their internship. 104 out of 133 responded (78%). Most of the house officers reported that they had received training and instruction in basic medical and surgical skills. However, more than 30% received no formal supervision in various emergency medical skills and the reported instruction in gynaecological skills was even worse. The female house officers were less likely than their male colleagues to report that they had attained various practical clinical skills. There was substantial variation in skills among respondents from different hospitals. Further studies into the quality of the preregistration internship, and the value of specific interventions, seem to be justified.

[Do the interns receive the supervision they are supposed to get?]

The Norwegian preregistration internship consists of 12 months duty as a house officer in hospitals (6 months in a surgical and 6 in a medical department) followed by 6 months in general practice. The survey assesses to what extent the intended information, supervision, feedback and internal evaluation assessment are offered the house officers during their hospital internship. A questionnaire was sent to all preregistration house officers who had recently finished their hospital duty, of whom 104 (78%) out of 133 responded. Half of the "medical" and 65% of the "surgical" house officers reported that they received no introductory information nor supervision before attending hospital duties. Two thirds did not participate in an educational programme and 80% did not receive systematic feedback on their work. Most house officers received no evaluation of their work at all. Specific interventions are needed to ensure high quality clinical training of the preregistration house officers.

Brain weight and sudden infant death syndrome

Increased brain weights have been reported in the literature to occur among infants who have died from sudden infant death syndrome, suggesting that cerebral edema might play a role in the cause of death among these children. We have compared brain weights from children between the ages of 1 week and 1 year, autopsied between 1980 and 1992. One group consisted of 125 victims of sudden infant death syndrome and the other of 38 children who had died with a diagnosis other than the sudden infant death syndrome. Brain weights from both groups exceeded the 50th percentile in previously published reference material. We were unable to show any significant differences between the groups in either the ratio between observed and expected brain weights or the ratio between brain weight and body weight. We conclude that there is no evidence for the notion that victims of sudden infant death syndrome have an increased brain weight. Other authors (in previous studies) may have overlooked the low overall weight at gestational age of prematurely born children while collecting data for reference levels. A revision of the figures seems to be necessary.

Chlamydia pneumoniae and chronic pharyngitis

Chlamydia pneumoniae has been implicated as an etiological agent for both upper and lower respiratory tract infections. We describe 4 cases of chronic pharyngitis where Chlamydia pneumoniae appears to be the etiological agent. All the patients were non-smokers, and had symptoms of more than 6 months' duration. Disease symptoms seemed to resolve following appropriate antibiotic treatment.

Sodium-calcium relationships and cardiac function during coronary bolus perfusion

The present review deals with the side-effects of contrast media (CM) on cardiac function during coronary angiography. A physiological approach is used to redefine existing concepts of CM osmotoxicity and chemotoxicity in terms of osmolal, ionic and molecular effects. The main idea conveyed is that purely ionic effects are of central importance during and immediately following the transit of a brief coronary bolus. Ionic effects result largely from rapid transient washout of normal extracellular ions, but are also influenced by ions present in the CM. In particular, the calcium (Ca) and sodium (Na) ions controlling cardiac function are easily affected. The myocardial Na-Ca exchange, which is mainly a physiological mechanism for cellular Ca efflux during cardiac relaxation, is therefore highlighted in detail. The importance of avoiding a potential Na-Ca mismatch is shown by examples from basic physiology, cardiac surgery and coronary angiography and by results of experiments with Visipaque. In the isomolal and isotonic CM Visipaque, which is based on the dimer isodixanol (320 mg I/ml), an available osmolal space is filled with an appropriately balanced supplement consisting of NaCl (19mM) and CaCl2 (0.3 mM).

Chlamydia pneumoniae (TWAR): a common agent in acute bronchitis

Patients seeking medical attention for respiratory infections were investigated with serology and culture for Chlamydia pneumoniae to investigate the prevalence of C. pneumoniae in a specific geographical area and its association with respiratory disease. Evidence for C. pneumoniae infection was found in approximately 25% of cases. 71% of patients with C. pneumoniae had symptoms from the lower respiratory tract as compared to 29% of the others. We conclude that C. pneumoniae can be a major cause of acute bronchitis.

[Pulmonary embolism as a late complication of heart contusion]

A 57 year-old woman was hospitalized because of a sternal fracture inflicted during a car accident. During the following two weeks she became breathless and was readmitted after having syncope, induced by exertion. A perfusion scan of the lungs showed pulmonary emboli in both the lower lobes. After anti-coagulation treatment her symptoms faded, but the ultrasonographic signs of pulmonary hypertension persisted for nearly four months. The probable mechanism behind the pulmonary embolism was transmural contusion of the right ventricle, leading to a mural thrombus which eventually became detached. The authors review the literature and discuss problems connected to the diagnostic criteria for cardiac contusion, as well as delayed complications, of which pulmonary embolism is a potentially lethal condition.