Inhibiting CSF1R alleviates cerebrovascular white matter disease and cognitive impairment

White matter abnormalities, related to poor cerebral perfusion, are a core feature of small vessel cerebrovascular disease, and critical determinants of vascular cognitive impairment and dementia. Despite this importance there is a lack of treatment options. Proliferation of microglia producing an expanded, reactive population and associated neuroinflammatory alterations have been implicated in the onset and progression of cerebrovascular white matter disease, in patients and in animal models, suggesting that targeting microglial proliferation may exert protection. Colony-stimulating factor-1 receptor (CSF1R) is a key regulator of microglial proliferation. We found that the expression of CSF1R/Csf1r and other markers indicative of increased microglial abundance are significantly elevated in damaged white matter in human cerebrovascular disease and in a clinically relevant mouse model of chronic cerebral hypoperfusion and vascular cognitive impairment. Using the mouse model, we investigated long-term pharmacological CSF1R inhibition, via GW2580, and demonstrated that the expansion of microglial numbers in chronic hypoperfused white matter is prevented. Transcriptomic analysis of hypoperfused white matter tissue showed enrichment of microglial and inflammatory gene sets, including phagocytic genes that were the predominant expression modules modified by CSF1R inhibition. Further, CSF1R inhibition attenuated hypoperfusion-induced white matter pathology and rescued spatial learning impairments and to a lesser extent cognitive flexibility. Overall, this work suggests that inhibition of CSF1R and microglial proliferation mediates protection against chronic cerebrovascular white matter pathology and cognitive deficits. Our study nominates CSF1R as a target for the treatment of vascular cognitive disorders with broader implications for treatment of other chronic white matter diseases.

Nox2 underpins microvascular inflammation and vascular contributions to cognitive decline

Chronic microvascular inflammation and oxidative stress are inter-related mechanisms underpinning white matter disease and vascular cognitive impairment (VCI). A proposed mediator is nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (Nox2), a major source of reactive oxygen species (ROS) in the brain. To assess the role of Nox2 in VCI, we studied a tractable model with white matter pathology and cognitive impairment induced by bilateral carotid artery stenosis (BCAS). Mice with genetic deletion of Nox2 (Nox2 KO) were compared to wild-type (WT) following BCAS. Sustained BCAS over 12 weeks in WT mice induced Nox2 expression, indices of microvascular inflammation and oxidative damage, along with white matter pathology culminating in a marked cognitive impairment, which were all protected by Nox2 genetic deletion. Neurovascular coupling was impaired in WT mice post-BCAS and restored in Nox2 KO mice. Increased vascular expression of chemoattractant mediators, cell-adhesion molecules and endothelial activation factors in WT mice post-BCAS were ameliorated by Nox2 deficiency. The clinical relevance was confirmed by increased vascular Nox2 and indices of microvascular inflammation in human post-mortem subjects with cerebral vascular disease. Our results support Nox2 activity as a critical determinant of VCI, whose targeting may be of therapeutic benefit in cerebral vascular disease.

Impaired Glymphatic Function and Pulsation Alterations in a Mouse Model of Vascular Cognitive Impairment

Large vessel disease and carotid stenosis are key mechanisms contributing to vascular cognitive impairment (VCI) and dementia. Our previous work, and that of others, using rodent models, demonstrated that bilateral common carotid stenosis (BCAS) leads to cognitive impairment via gradual deterioration of the neuro-glial-vascular unit and accumulation of amyloid-β (Aβ) protein. Since brain-wide drainage pathways (glymphatic) for waste clearance, including Aβ removal, have been implicated in the pathophysiology of VCI via glial mechanisms, we hypothesized that glymphatic function would be impaired in a BCAS model and exacerbated in the presence of Aβ. Male wild-type and Tg-SwDI (model of microvascular amyloid) mice were subjected to BCAS or sham surgery which led to a reduction in cerebral perfusion and impaired spatial learning acquisition and cognitive flexibility. After 3 months survival, glymphatic function was evaluated by cerebrospinal fluid (CSF) fluorescent tracer influx. We demonstrated that BCAS caused a marked regional reduction of CSF tracer influx in the dorsolateral cortex and CA1-DG molecular layer. In parallel to these changes increased reactive astrogliosis was observed post-BCAS. To further investigate the mechanisms that may lead to these changes, we measured the pulsation of cortical vessels. BCAS impaired vascular pulsation in pial arteries in WT and Tg-SwDI mice. Our findings show that BCAS influences VCI and that this is paralleled by impaired glymphatic drainage and reduced vascular pulsation. We propose that these additional targets need to be considered when treating VCI.

Foreign body ingestion in children

INTRODUCTION

Evaluation of results of the group of paediatric patients treated for swallowed foreign bodies in the digestive tract.

METHODS

Retrospective analysis of patients treated for foreign bodies in the digestive tract, managed at the University Hospital of Hradec Králové between 2011-2018.

RESULTS

365 patients (182 boys, 183 girls) with a foreign body in the digestive tract have been evaluated. The mean age was 2.4 years. Most of the children were treated as outpatients (280 children, 76.7%) and only 85 children (23.3%) were hospitalized. The most commonly swallowed frequent bodies included coins (26%) and batteries (14.5%); sharp objects occurred in 5.2%. Unusual foreign bodies were noticed, too. We can mention for example a pen or a plant nutrition product. In 302 cases (82.7%) the foreign bodies passed easily per vias naturales. Endoscopy was necessary in 63 cases (17.2%) - in 51 children the object had to be removed from the oesophagus and in 12 children the object had to be removed from the stomach. None of the swallowed bodies caused complications such as digestive tract perforation or bowel obstruction. No patient in the group was indicated for laparotomy to remove the foreign body.

CONCLUSION

Foreign bodies entrapped in the oesophagus have to be removed endoscopically. In most cases, foreign bodies in the stomach require only observation in the outpatient setting because they leave the stomach easily, without complications, per vias naturales. If a battery remains at the same place of the digestive tract for more than 24 hours, endoscopic removal is indicated at our department. In addition, endoscopy is done in cases of swallowed multiple magnets or bodies that are too large and remain in stomach for several weeks or months. Surgical removal of foreign bodies should be reserved only for complicated cases.

[Open versus laparoscopic appendectomy for acute appendicitis in children]

INTRODUCTION

Acute appendicitis is a common disease affecting both adults and children. The basic therapeutic procedure is an appendectomy. Open appendectomy has been gradually supplemented and sometimes replaced by a laparoscopic approach in numerous departments. The aim of our work was to compare laparoscopic and open surgery objectively.

METHOD

Retrospective analysis of data from patients operated on at the Department of Pediatric Surgery and Traumatology, Teaching Hospital in Hradec Králové in 20092016. Only the precisely evaluated parameters, i.e. the time of anesthesia, the time of surgery and the duration of post-operative pain, were assessed within the scope of objectification. Data were evaluated only in a homogeneous group of patients with phlegmonous appendicitis.

RESULTS

During the above period, 261 patients with acute appendicitis were operated on at our department, 166 of whom suffered from phlegmonous appendicitis. 133 children were operated laparoscopically and 33 by open procedure. The results obtained were statistically significantly different only for the time of anesthesia (p=0.00035) which was shorter in open operations. The time of surgery was also shorter in the open operation group, but only at the limit of statistical significance. A statistically significant difference was not found in the time of duration of pain for individual surgical approaches.

CONCLUSION

Laparoscopic approach in the surgical treatment of acute appendicitis is a more modern method than open surgery and it has become a standard procedure in some departments. However, the results of our study confirm that the open approach remains an equivalent alternative to the treatment of acute phlegmonous appendicitis.Key words: appendicitis open appendectomy laparoscopy.

Long-term cilostazol treatment reduces gliovascular damage and memory impairment in a mouse model of chronic cerebral hypoperfusion

Chronic cerebral hypoperfusion is a major cause of age-related vascular cognitive impairment. A well-characterised mouse model has shown that hypoperfusion results in gliovascular and white matter damage and impaired spatial working memory. In this study, we assessed whether cilostazol, a phosphodiesterase III inhibitor, could protect against these changes. Adult, male C57Bl/6J mice were subjected to bilateral common carotid artery stenosis or a sham operation and fed normal or cilostazol diet for three months. Cilostazol treatment reduced the impairment in working memory and white matter function after hypoperfusion. Endothelial adhesion molecules and gliosis, increased after hypoperfusion, were ameliorated with cilostazol treatment. Interestingly, the improvement in working memory was closely correlated with reduced microglia and endothelial adhesion molecules. Further, the number of stroke lesions after hypoperfusion was reduced in the cilostazol-treated group. Altogether cilostazol showed potential to ameliorate the gliovascular damage and working memory impairments after hypoperfusion possibly via endothelial protection supporting its potential use in the treatment of vascular cognitive impairment.

Genetic dissection of TrkB activated signalling pathways required for specific aspects of the taste system

Background

Neurotrophin-4 (NT-4) and brain derived neurotrophic factor (BDNF) bind to the same receptor, Ntrk2/TrkB, but play distinct roles in the development of the rodent gustatory system. However, the mechanisms underlying these processes are lacking.

Results

Here, we demonstrate, in vivo, that single or combined point mutations in major adaptor protein docking sites on TrkB receptor affect specific aspects of the mouse gustatory development, known to be dependent on BDNF or NT-4. In particular, mice with a mutation in the TrkB-SHC docking site had reduced gustatory neuron survival at both early and later stages of development, when survival is dependent on NT-4 and BDNF, respectively. In addition, lingual innervation and taste bud morphology, both BDNF-dependent functions, were altered in these mutants. In contrast, mutation of the TrkB-PLCγ docking site alone did not affect gustatory neuron survival. Moreover, innervation to the tongue was delayed in these mutants and taste receptor expression was altered.

Conclusions

We have genetically dissected pathways activated downstream of the TrkB receptor that are required for specific aspects of the taste system controlled by the two neurotrophins NT-4 and BDNF. In addition, our results indicate that TrkB also regulate the expression of specific taste receptors by distinct signalling pathways. These results advance our knowledge of the biology of the taste system, one of the fundamental sensory systems crucial for an organism to relate to the environment.

Loss of NGF-TrkA signaling from the CNS is not sufficient to induce cognitive impairments in young adult or intermediate-aged mice

Many molecules expressed in the CNS contribute to cognitive functions either by modulating neuronal activity or by mediating neuronal trophic support and/or connectivity. An ongoing discussion is whether signaling of nerve growth factor (NGF) through its high-affinity receptor TrkA contributes to attention behavior and/or learning and memory, based on its expression in relevant regions of the CNS such as the hippocampus, cerebral cortex, amygdala and basal forebrain. Previous animal models carrying either a null allele or transgenic manipulation of Ngf or Trka have proved difficult in addressing this question. To overcome this problem, we conditionally deleted Ngf or Trka from the CNS. Our findings confirm that NGF-TrkA signaling supports survival of only a small proportion of cholinergic neurons during development; however, this signaling is not required for trophic support or connectivity of the remaining basal forebrain cholinergic neurons. Moreover, comprehensive behavioral analysis of young adult and intermediate-aged mice lacking NGF-TrkA signaling demonstrates that this signaling is dispensable for both attention behavior and various aspects of learning and memory.

[Retrogastric bronchogenic cyst]

The authors present a case of an incidental finding of an asymptomatic retrogastricaly localized bronchogenic cyst. In a 3.5 year old boy, abdominal US, which was performed because of constipation complains, revealed a cystic mass. MRI study confirmed the presence of a simple cyst, located in the retrogastric region. The patient underwent laparotomy and the cyst, measuring 3 cm in a diameter, was removed from the omental bursa. During the postoperative period, no complications or symptoms were recorded. Histologicaly, the finding was surprisingly identified as a bronchogenic cyst. Occurence of bronchogenic cysts within the abdominal cavity is reported very rarely in the literature.

Laceration and degloving injury of a child's foot--a case report

Laceration and degloving injury to a child's foot is quite a rare occurence, mostly resulting in persistent consequences. Treatment options for such an injury depend on the specific type of injury and the customary practice of each surgical department. The authors present the interesting case of 4-year-old boy with laceration and degloving injury to his right foot after a collision with a truck, suggesting simple treatment using skin graft which has an excellent functional and cosmetic effect. Several methods have been described in management of this kind of injury, such as microvascular free tissue transfer, free or local flap and skin graft. A full-thickness skin graft was used in this case with good result, and in our opinion this treatment option need not be reserved for plastic surgeons.

[Rupture of the interventricular septum after the blunt trauma of thorax]

Authors present the case of little patient with the dissection, pseudoaneurysm and finally a rupture of the interventricular septum after the blunt thracic injury. The patient was smitten as a pedestrian by a car and during the whole period of her stay in the hospital she was showing signs of circulatory instability. Due to the current intraabdominal injuries this circulatory decompensation was first assigned to hemoperitoneum, for which the girl was operated on about 3 hours after admission. Nevertheless, even after the abdminal cavity check, after the treatment of supreficial liver lacerations and intensive volume resuscitation the patient showed signs of insufficiency. Diagnosis was finally determined on the base of the transthoracic echocardiography (TTE), which proved the traumatic rupture of interventricular septum. The operation followed correcting the defect, which was performed with a good result according to the TTE postoperatively. Nevertheless, 27 hours after the admission the patient died due to the electromechanical dissociation. In the discussion the authors then evoke a number of papers concerning the same topic.

[A ventral slit of the prepuce in phimosis]

The appearance of the penis after circumcision is frequently not appreciated favourably by the patients nor their parents. An alternative surgical method in phimosis is a ventral slit of the prepuce. When properly indicated, an almost normal appearance of the prepuce is preserved. This operation was performed in 25 boys. An ideal result, where an almost normal shape of the prepuce is preserved and the latter can be drawn over the glans, was achieved in 19 patients. In four boys the prepuce can be freely drawn over the glans but a slight strangulation ring forms. A relapse of phimosis occurred in two boys. The authors recommend to use ventral slit of the prepuce instead of circumcision in children with phimosis, when the prepuce is sufficiently long. The method is not suitable for short prepuces with cicatricial phimosis.

[Cysts and pseudocysts of the spleen in children]

A cyst in the upper pole of the spleen was diagnosed in three children. In all the pole of the spleen was resected -in two instances it contained a cyst, in one a pseudocyst. The postoperative course was without complications. All patients had scintigraphic check-up examinations, in all three instances functional lienal tissue was found which did not differ much as to its size from that of a normal spleen. In cysts situated in the splenic pole the authors consider partial resection of the affected portion of the spleen as the optimal surgical method. In cysts of other portions of the spleen it would be better to select a different surgical procedure, e.g. enucleation of the cysts, partial decapsulation of the cyst or percutaneous puncture of the cyst combined, if necessary, with sclerotization.

[Laparoscopy-assisted appendectomy in children]

During a 13-month period (March 1, 1995 March 31, 1996) the authors performed in 70 children a laparoscopically assisted appendectomy. 68 children were operated on account of chronic appendicitis, two on account of acute appendicitis. During the postoperative period early, not very serious, postoperative complications were recorded in 7 children. One girl had on the second day after operation fever and severe abdominal pain, four children developed on the 5th-7th day after surgery abdominal pain, associated in three instances with fever and in two instances with the pathological finding of pericoecal fluid. The complaints receded within 1-2 days in all five patients after conservative treatment. In another two children the wound healed per secundam intentionem. No late complications were recorded.

A simplified procedure for studies of intestinal immunity in rabbits

As interest in the development of oral vaccines continues to rise, alternative animal models for studies of mucosal immunity are needed. The present study examines a simplified procedure for delivering antigen to rabbit Peyer's patches via an indwelling cannula. The cannula was placed 3-4 cm proximal to the Peyer's patch, and was used to deliver four weekly doses of the potent mucosal immunogen, cholera toxin (CT). Anti-CT specific fecal secretory IgA (S-IgA), serum IgG and serum IgA were found in essentially equal amounts in rabbits with cannulas and in rabbits fitted with Thiry-Vella (T-V) isolated ileal loops. In contrast to animals with T-V loops, the intestinal flora of animals with cannulas contained less bacterial overgrowth with Pseudomonas sp. Further, the villus architecture remained histologically normal in appearance and there were fewer post-surgical complications associated with this technique than with T-V loops. This simplified technique should allow wider use of rabbits in studies of mucosal immunity.

[Disorders of intestinal rotation and fixation in older children]

The authors discuss five older children where malrotation of the gut was diagnosed. The youngest child was three years old, the oldest 16 years. In three children the malrotation was diagnosed from clinical symptoms and examination by imaging methods, in two it was detected by chance during operation. In the two children where the impaired rotation of the gut was detected on operation, non-rotation was involved. In the remaining three children twice a left side paraduodenal hernia was diagnosed and once an external stenosis of the duodenum by Ladd's bands.

[Comparison of the results of conservative and surgical therapy of dislocated supracondylar fractures of the humerus in children]

The authors evaluate retrospectively in a group of 121 children with a dislocated supracondylar fracture in 1984-1993 the results of different therapeutic methods. The highest percentage of excellent and satisfactory results was recorded in children treated by closed reposition with percutaneous pinning with Kirschner wires (88%). In open reposition with Kirschner wires 60% of the results were excellent of satisfactory. The lowest percentage of excellent and satisfactory results was recorded when fixation with a plaster bandage was used (48%). The highest percentage of poor results was observed in surgical reposition with internal fixation (37%). The cause of failure in the majority of patients is according to the authors inadequate reposition of fragments. The authors discuss different types of treatment. They recommend non-surgical reposition with percutaneous pinning, even for less dislocated extension supracondylar fractures of the humerus as well as for fractures complicated by vascular injuries.

[A solitary congenital hepatic cyst]

The author discusses a congenital, solitary, multilocular liver cyst in a two-year-old boy. The cyst originated in the margo ventralis of the right liver lobe. Clinically it was manifested by marked enlargement of the abdomen. The diagnosis was established by ultrasonography. The whole cyst was removed surgically.

[Adnexal torsion in childhood]

During the 7-year period (1987-1993) the authors treated nine girls on account of torsion of the adnexa. In six girls torsion of primarily unaltered adnexa occurred, in one girl torsion of an ovary enlarged by a cyst and in two torsion of the ovary affected with a benign tumour, a coetaneous teratoma. In seven instances the organ affected with ischaemic necrosis had to be resected. In two girls detorsion of the ovary was performed, according to a sonographic control examination, however, in one the affected ovary atrophied. In the discussion the authors deal with the diagnosis of torsion of the adnexa and the method of treatment. The authors consider ultrasonic examination of organs of the abdominal cavity and retroperitoneum a very suitable method in all cases of abdominal pain in childhood, as this method can greatly contribute to the diagnosis of acute abdominal and gynaecological attacks. During surgery they recommend to preserve adnexa with a doubtful vitality because there is certain hope that they will be saved. During the postoperative period they recommend the long-term follow up of girls clinically and by ultrasonographic checks. If pathological changes are detected on the preserved adnexa, they recommend early re-operation and elimination of the risk factor (cysts etc.). The operation should be supplemented by prophylactic fixation of the preserved adnexa if this fixation was not done already during the primary operation.

[Diagnosis and therapy of post-traumatic hemobilia]

The submitted case-history deals with a successfully diagnosed and treated case of post-traumatic hemobilia in a 13-year-old girl. Hemobilia was manifested clinically by the typical Sandblom triad of symptoms. It was due to a pseudoaneurysm of the peripheral arteriole of the hepatic artery diagnosed by selective liver angiography. In treatment selective intraarterial embolization of the supplying artery proved useful.

[Splenosis]

Four patients where during childhood splenectomy was performed on account of a traumatic indication were after 9-12 years subjected to sonographic and scintigraphic examination focused on possible evidence of splenosis. In one case asymptomatic splenosis was detected by scintigraphy.

[Conservative therapy of liver injuries in children]

During the 14-year period between 1979 and 1992 the authors treated by conservative methods nine children with liver injuries. They operated on four children. The liver injury did not bleed during operation or haemorrhage was only minimal and probably the patients would have also recovered after conservative treatment. In the discussion the authors mention diagnostic approaches in liver injuries and criteria and methods of conservative treatment. The authors consider conservative treatment of liver injuries in children to be a very suitable method which is associated only with a very small number of complications, and which proves successful in the majority of patients. The prerequisite for its application are high standard of diagnostic visualization methods, monitoring of the child's condition and the possibility of immediate surgery, if conservative treatment fails.

Giant Meckel's diverticulum

A case of incomplete intestinal obstruction caused by a giant Meckel's diverticulum in a 13-year-old girl is reported. Short resection of the ileum with the diverticulum and end-to-end anastomosis was carried out. The possibilities of diagnosis and treatment as well as the controversial classification of this rare congenital anomaly are discussed.

Endoscopic retrograde cholangiopancreatography in childhood

ERCP was performed in 19 children and adolescents aged 4 to 16 years. In 13 children the examination was done under general anesthesia, in 6 cases with the usual premedication using dolsin and atropine. Indications for examination were unclear abdominal pain with occasional amylase elevation, in 3 patients status after an abdominal injury. In 16 patients the examination clarified the complaints by detecting organic disease of the gallbladder or the pancreas. ERCP is an important procedure in the event of uncertain diagnosis in children and adolescents and, if the indication is correct, and the technique good, is well tolerated by the patients.

[The significance of endoscopic retrograde cholangiopancreatography in the diagnosis of pancreatic injuries in children]

The condition of the main pancreatic duct determines very probably in a decisive way the fate of posttraumatic pancreatic pseudocysts and acute pancreatic injuries. Endoscopic retrograde cholangiopancreatography is the only diagnostic method which makes possible to evaluate the condition of this duct. The authors performed ERCP in three children, in two of them an internal drainage of the pseudocyst was carried out on account of verified ductal rupture. In the third girl, after evidence of an intact main pancreatic duct, conservative therapy was successfully applied. In the discussion the authors summarize data from the literature regarding the use of ERCP in the preoperative diagnosis of posttraumatic pancreatic pseudocysts and acute pancreatic injuries. The authors consider ERCP a method which renders the diagnosis of posttraumatic pancreatic pseudocysts and acute pancreatic injuries more accurate.

[Air gun injuries in children]

The authors describe four cases of air rifle child injuries. One was a potentially lethal injury, a penetrating wound of the transverse colon and injury to the stomach. During urgent laparotomy the perforations of the gastrointestinal tract were sutured. In the remaining three children the injuries were less serious and affected soft tissues. In the discussion the authors summarize data from the literature concerning injuries to the head, neck, chest, abdomen and extremities, incl. lethal injuries. In instances when a penetrating abdominal injury cannot be ruled out, the authors emphasize the necessity of urgent laparotomy and surgical treatment of possible intraabdominal lesions. In injuries to other parts of the body a strictly individual procedure focused on repair of the injury is indicated. The authors also emphasize prevention of these injuries by adherence to safety during shooting and other manipulations with arms an air rifle must not be a toy for children and adolescents unless they are supervised by a responsible adult.

[Acalculous gangrenous cholecystitis in a toddler]

The authors describe a case of acute gangrenous cholecystitis in a 17-month-old boy manifested by symptoms of an inflammatory acute abdomen after several days of a febrile condition associated with diarrhoea. Cholecystectomy was performed and after antibiotic and infusion therapy a noncomplicated postoperative development followed. Five years after operation the boy has no subjective complaints. In the discussion the authors analyze the incidence, aetiopathogenesis, clinical, laboratory and X-ray findings of this rare disease. For the therapy of advanced cholecystitis the authors recommend cholecystectomy.

[Ileus in an infant caused by a ventriculoperitoneal shunt]

The authors describe a case of adhesive ileus caused by the intraperitoneal part of a ventriculoperitoneal shunt which was performed on account of congenital hydrocephalus. Preserving the patency of the ventriculoperitoneal drainage, the ileus was treated according to principles of abdominal surgery. The functional catheter was left in situ. Complete intestinal occlusion is one of the very rare intraabdominal complications of ventriculoperitoneal shunt. In the discussion the authors analyze available data from the literature on intestinal occlusion with the above aetiology.

Bis(monoazacrown ethers) with an electron-donating substituent at the hinge: A pronounced participation of hydroxyl group in formation of sodium ion sandwich complexes

Sodium ion complex formation has been investigated potentiometrically in four homologous bis(crown) series I-IV differing by the nature of substituent placed at the linking trimethylene chain (X = OH, OCH3, OCH2C6H5 and H respectively). A marked enhancement of the complex stability has been observed in the bis(crown) series I and attributed to participation of the lateral hydroxyl group in the sandwich complex formation. Evidence in support of the sandwich structure has been provided (i) by analysis of the potentiometric data indicating a 1:1 complex stoichiometry and (ii) by a comparison of the complex stability data from the bis(crown) series I with the corresponding values from related monocyclic ligand series V, VI and VII revealing a pronounced cooperation of both macrorings in the sodium ion-bis(crown) I complex formation.

[Microbiological quality of dried milk products for child nutrition in Czechoslovakia]

In the course of four years, 20 175 samples of milk powder products for baby foods were examined. On an average, 1.18% of the products did not comply with the requirements of the Czechoslovak State Standards. Total microbe number higher than required by the standard was found in 0.36% of the samples, on an average, higher counts of enterococci in 1.02%; coliform micro-organisms were found in 0.78% of the samples. Staphylococci and salmonellae were absent. Moulds were present in 34 samples (Aspergillus flavus without the production of aflatoxin).

Interaction of phenosafranine with nucleic acids and model polyphosphates. I. Self-aggregation and complex formation with inorganic polyphosphates

Aggregation of phenosafranine in concentrated aqueous solutions and interaction with polyphosphates was studied by absorption and fluorescence spectroscopy. At concentrations greater than 10(-3)M phenosafranine forms dimers (Kd = 3.8 x 10(2) 1.mole-1), which are characterized by a hypsochromic shift of the visible and near ultraviolet absorption maxima accompanied by a hypochromic effect. No fluorescence could be detected from phenosafranine dimers. Analogues spectra changes were observed when a polyphosphate was titrated with phenosafranine, which indicated that with increasing saturation of the polyphosphate binding sites phenosafranine gradually became bound in the aggregated form. Full saturation of the polyphosphate binding sites with phenosafranine was reached only when an excess of free dye was present. The cooperative binding of phenosafranine to a polyphosphate could be evaluated by means of a theory proposed by Schwarz et al. At the zero ionic strength and at 25 degrees C the binding was characterized by cooperative binding constant K = 6.2 x 10(5) 1.mole-1, number of binding sites per monomeric phosphate residue g = 0.4, and cooperativity parameter q-30. Spectroscopic properties of phenosafranine in the aggregated and polyphosphate-bound states were compared with those of ethidium bromide.

Interaction of phenosafranine with nucleic acids and model polyphosphates. I. Self-aggregation and complex formation with inorganic polyphosphates

Aggregation or phenosafranine in concentrated aqueous solutions and its interaction with polyphosphates was Studied by absorption and fluorescence spectroscopy. At concentrations > 10(-3) M phenosafranine forms dimers (Kd = 3.8 x 10(2) l.mole(-1)), which are characterized by a hypsochromic shift of the visible and near ultraviolet absorption maxima accompanied by a hypochromic effect. No fluorescence could be detected from phenosafranine dimers. Analogous spectral changes were observed when a polyphosphate was titrated with phenusafranine, which indicated that with increasing saturation of the polyphosphate binding sites phenosafranine gradually became bound in the aggregated form. Full saturation of the polyphosphate binding sites with phenosafranine was reached only when an excess of free dye was present. The cooperative binding of phenosafranine to a polyphosphate could be evaluated by means of a theory proposed by Schwarz et al. At the zero ionic strength and at 25 degrees C the binding was characterized by cooperative binding constant K = 6.2 x 10(5) l.mole(-1), number of binding sites per monomeric phosphate residue g = 0.4, and cooperativity parameter q reverse similar 30. Spectroscopic properties of phenosafranine in the aggregated and poly phosphate-bound stotes were compared with those of ethidium bromide.

A compact form of double-stranded RNA in solutions containing poly(ethyleneglycol)

Molecules of single-stranded ribosomal RNA and double-stranded replicative form of phage f2 RNA (dsRNA) adopt a compact form in solutions, containing sufficiently high concentrations of salt (NaCl) and polymer (PEG). However, only in the cases of native dsRNA molecules the compact particles are characterized by a regular internal structure, which accounts for the appearance of an intense positive band in CD spectra. Heating or acidification of PEG-containing solutions of dsRNA leads to the disappearance of the intense positive CD band, which results from the "destruction" of the regular internal structure of compact particles. Comparison of properties of DNA and dsRNA compact particles formed in PEG-containing water-salt solutions suggests the existence of similar mechanisms of compactization of double-stranded polynucleotides.

Mechanism of the mutagenic action of hydroxylamine. VIII. Functional properties of the modified adenosine residues

The action of O-methylhydroxylamine in vitro upon some amber and rII ochre mutants of T4 phage leads to a considerable increase in the frequency of reversions and conversions of ochre and opal mutants presumably due to A yields G transitions. The transitions seem to be caused by modification of the adenine bases of the genome to give N-6-methoxyadenine which has equivocal (A- and G-like) specificity. However, the functional activity of N-6-methoxyadenosine residues in the RNA polymerase system is low. We failed to detect any significant activity of these residues either as components of a template polyribonucleotide, or as nucleoside triphosphate precursors.