Comparison of moderate hyperventilation and mannitol for control of intracranial pressure control in patients with severe traumatic brain injury--a study of cerebral blood flow and metabolism.

OBJECTIVE: To compare the respective effects of established measures used for management of traumatic brain injury (TBI) patients on cerebral blood flow (CBF) and cerebral metabolic rates of oxygen (CMRO2), glucose (CMRGlc) and lactate (CMRLct). METHODS: Thirty-six patients suffering from severe traumatic brain injury (TBI) were prospectively evaluated. In all patients baseline assessments were compared with that following moderate hyperventilation (reducing PaCO2 from 36 +/- 4 to 32 +/- 4 mmHg) and with that produced by administration of 0.5 gr/kg mannitol 20% intravenously. Intracranial and cerebral perfusion pressure (ICP, CPP), CBF and arterial jugular differences in oxygen, glucose and lactate contents were measured for calculation of CMRO2, CMRGlc and CMRLct. RESULTS: Following hyperventilation, CBF was significantly reduced (P < 0.0001). CBF remained most often above the ischemic range although values less than 30 ml x 100 gr(-1) x min(-1) were found in 27.8% of patients. CBF reduction was associated with concurrent decrease in CMRO2, anaerobic hyperglycolysis and subsequent lactate production. In contrast, mannitol resulted in significant albeit moderate improvement of cerebral perfusion. However, administration of mannitol had no ostensible effect either on oxidative or glucose metabolism and lactate balance remained mostly unaffected. CONCLUSIONS: Moderate hyperventilation may exacerbate pre-existing impairment of cerebral blood flow and metabolism in TBI patients and should be therefore carefully used under appropriate monitoring. Our findings rather support the use of mannitol for ICP control.

Role of brain natriuretic peptide in cerebral vasospasm.

BACKGROUND: Brain natriuretic peptide (BNP) is a potent natriuretic factor responsible for hyponatremia observed in patients with SAH. Through its systemic effects (reduction of blood volume and blood pressure) BNP may augment cerebral blood flow reduction and ischemia secondary to vasospasm. The purpose of the present study was to evaluate the relationship between BNP plasma concentration during the first 12 days following SAH and the development of cerebral vasospasm (CVS). The authors propose a hypothesis for the role played by natriuretic peptides in the pathophysiology of cerebral vasospasm based on the present findings and review the literature. METHODS: Thirty eight patients with spontaneous SAH were prospectively included in the present study. BNP plasma concentrations were assessed at four different time periods following SAH (day 1-3, 4-6, 7-9, 10-12). TCD evidence of CVS was found in 26 patients (68.5%), fourteen patients (36.8%) had delayed ischemic neurological deficits (DIND). FINDINGS: Initial BNP plasma concentrations were significantly more elevated in patients who eventually did not develop DIND (95.07+/-107.65 pg/ml vs. 25.81+/-22.57 pg/ml, p=0.0053). However, in patients with DIND, the BNP plasma concentration increased by 3.69 ( p<0.05), 5.89 ( p<0.001) and 4.54 fold ( p<0.001) between days 1-3 to days 4-6, 7-9 and 10-12 respectively (day 1 was regarded as the day of hemorrhage). In patients without CVS or asymptomatic CVS the BNP plasma concentration decreased between days 1-3 to day 10-12. A similar trend in BNP plasma concentration was found in patients with severe SAH (Fisher's score 3-4) as compared with patients with non visible or moderate SAH (BNP concentration ratio day 7-9/1-3: 4.37 vs. 0.75, p=0.015; day 10-12/1-3: 3.37 vs. 0.3, p=0.0144). The trend in BNP plasma concentration between day 1-3 to day 7-9 was found to correlate with CVS severity with an average increase of 2.01, 3.8 and 5.44 fold for mild, moderate and severe VS respectively ( p<0.01, r=0.4174). INTERPRETATION: These results suggest that BNP secretion in SAH patients is closely related to the bleeding intensity and vasospasm severity as well as to development of DIND with a progressive and marked increase during the clinical course in patients who eventually develop cerebral ischemia. Taken together the local and systemic effects of BNP on CBF suggest that BNP might play a role in the pathophysiology of CVS through its systemic effects on blood pressure and plasma volume BNP leading to an aggravation of brain ischemia secondary to vasospasm.

Basilar vasospasm following spontaneous and traumatic subarachnoid haemorrhage: clinical implications.

BACKGROUND: Cerebral vasospasm has been commonly described following subarachnoid haemorrhage (SAH) though its impact on neurological outcome, especially in head trauma, has not been yet elucidated. The purpose of this study was to monitor and correlate neurological condition and flow velocities (FVs) in the arteries of the brain after SAH and more particularly to investigate the influence of basilar artery (BA) vasospasm on neurological outcome. METHODS: Daily transcranial Doppler (TCD) evaluations were conducted in 116 consecutive patients with subarachnoid haemorrhage. SAH was of traumatic origin (tSAH) in 59 patients and spontaneous (sSAH) in 57 patients. Vasospasm in the MCA and ACA was defined by a mean FV exceeding 120 cm/s and three times the mean FV of the ipsilateral ICA. Basilar artery (BA) vasospasm was defined as moderate whenever the FV was higher than 60 cm/s and severe above 85 cm/s. FINDINGS: Sixty-two patients (53.4%) had elevated FVs in the BA, among these 34 (29.3%) had FVs above 85 cm/s. Basilar vasospasm was significantly more common in tSAH (59.7%) than in sSAH (40.3%, P=0.041). In patients with moderate and severe BA vasospasm, FVs in the BA increased on the third day after admission and remained elevated for a week before returning to normal value by the end of the second week. This elevation in BA FVs in patients with BA vasospasm was followed by a significant and progressive worsening in the neurological condition at the end of the first week. Permanent neurological deficit was associated with elevated BA FVs consistent with moderate BA vasospasm whereas patients who remained in persistent vegetative state, had FVs consistent with severe BA vasospasm (P=0.00019). INTERPRETATION: The present results further support that BA vasospasm may act as an independent factor of ischaemic brain damage following SAH, especially in head trauma.

Sequence analysis by hybridization with oligonucleotide microchip: identification of beta-thalassemia mutations.

Diagnostics for genetic diseases were run and sequence analysis of DNA was carried out by hybridization of RNA transcripts with oligonucleotide array microchips. Polyacrylamide gel pads (100 x 100 x 20 microm) were fixed on a glass slide of the microchip and contained allele-specific immobilized oligonucleotides (10-mers). The RNA transcripts of PCR-amplified genomic DNA were fluorescently labeled by enzymatic or chemical methods and hybridized with the microchips. The simultaneous measurement in real time of the hybridization and melting on the entire oligonucleotide array was carried out with a fluorescence microscope equipped with CCD camera. The monitoring of the hybridization specificity for duplexes with different stabilities and AT content was enhanced by its measurement at optimal, discrimination temperatures on melting curves. Microchip diagnostics were optimized by choosing the proper allele-specific oligonucleotides from among the set of overlapping oligomers. The accuracy of mutation detection can be increased by simultaneous hybridization of the microchip with two differently labeled samples and by parallel monitoring their hybridization with a multi-wavelength fluorescence microscope. The efficiency and reliability of the sequence analysis were demonstrated with diagnostics for beta-thalassemia mutations.

[Chromosomal proteins in chick embryo erythrocytes on transcriptionally active and inactive genes]. / Khromosomnye belki éritrotsitov émbrionov kur na transkriptsionno aktivnykh i neaktivnykh genakh.

Using chicken embryonic erythrocytes as a model, an experimental scheme for comparing the density of linker histones and high mobility group proteins on single-copy sequences of eukaryotic genome has been developed, thus permitting to probe alterations in the chromosomal protein pattern of transcribing chromatin. The report provides experimental evidence for validity of intracellular DNA-protein cross-linking, immunoaffinity chromatography and hybridization with single-stranded probes. Depletion of linker histones and enrichment of HMG 14/17 were shown to be the discriminating feature for transcriptionally active globin gene chromatin as opposed to inactive ovalbumin and lysozyme gene chromatin.

[Primary organization of nucleosome core particles in active and repressed nuclei]. / Pervichnaia organizatsiia minimal'nykh nukleosom aktivnykh i repressirovannykh iader.

A refined high-resolution map for the linear arrangement of histones along DNA in the nucleosomal core particles has been determined by DNA-protein crosslinking. Histones are aligned on one strand of the 145 bp core DNA in the following order: (5') H2B25,35--H455,65--H375,85,, 95/H488--H2B105, 115--H2A118--H3135, 145/H2A145 (3') (the subscripts indicate the approximate distance in nucleotides of the main histone binding sites from the 5'-end of the core DNA). This suggests a symmetrical and rather autonomous arrangement of the histone tetramer (H3, H4)2 and two dimers (H2A, H2B) on the double-stranded core DNA: H2A/H3--(H2A, H2B)--(H3, H4)2--(H2B, H2A)--H3/H2A. The arrangement of histones on DNA was found to be very similar for the cores isolated from the repressed nuclei of sea urchin sperm and chicken erythrocytes and from the active in transcription and replication Drosophila embryo and yeast nuclei. This indicates that the core nucleosome structure is highly conserved through evolution and that the overall inactivation of chromatin does not affect the primary organization of the cores. A new binding site H2B58 was found for a sea urchin spermal variant of H2B which contains an additional basic segment within the N-terminal part of the molecule. The core isolation procedure was shown to introduce changes into the core structure which are reflected in the appearance of a new binding site H2A75.

[Contacts of Escherichia coli RNA polymerase subunits with nucleotides of lacUV5 promoter]. / Kontakty mezhdu sub"edinitsami RNK-polimerazy Escherichia coli i nukleotidami promotora lacUV5.

We have localized contacts between DNA and subunits of E. coli RNA polymerase (of both holo and core enzymes) along lacUV5 promoter. In the complex with the holo enzyme the anti-sense strand of DNA makes contacts with beta' subunit at -47, -46, -30, -12, +1, +5, +7, +9; beta subunit at -30, -25, -23, -12, +11, +30 and delta subunit at -17, -5, -3 nucleotides, while the sense-strand of DNA makes contacts with beta' subunit at -22, -21, -9, -6, -4, +3, +4, +6, +17; beta subunit at +17, +25, +27, +34; and delta subunit at -35, -18 nucleotides. In the complex with the core enzyme the anti-sense strand of DNA makes contacts with beta'subunit at -47, -23, -5, -3, +5, +7, +9; beta subunit at -23, -16, +11, +30 nucleotides while the sense-strand of DNA makes contacts with beta' subunit at -20, -19, +3, +4, +6, +17; beta subunit at -36, -35, -34, -31, -29, +17, +25, +27, +34 nucleotides alpha subunits of the holo as well as the core enzyme show no contact with DNA in the conditions providing specific complex formation.

[Interaction of histones with DNA in chromatin. A new method of covalent binding of histones to DNA available for their localization on DNA]. / Vzaimodeistvie gistonov s DNK v khromatine. Novyi metod kovalentnogo sviazyvaniia gistonov s DNK, udobnyi dlia ikh lokalizatsii na DNK.

A new method for covalent binding of histones to partially apurinized DNA was developed. Partial apurinization of DNA methylated within the composition of chromatin results in a formation of aldehyde groups interacting with the epsilon-amino groups of chromatin proteins lysine residues. The resulting Schiff's bases covalently and reversibly bind the protein molecules to DNA. This covalent binding is accompanied by a specific one-chain cleavage of DNA at the cross-linkage point in such a way that only the newly formed 5'-terminal fragment of DNA in bound to the protein. These cross-links can be stabilized via reduction of Schiff's bases by sodium borohydrate. Determination of the size of the bound DNA fragment allows to establish the localization of the cross-linkage point and the position of the protein molecule on DNA. The method of cross-linkage with a "zero length" allows to fix the immediate DNA--protein interactions and can be extensively used to study the protein--DNA interactions in cases when the epsilon-amino groups of protein lysine residues interact with DNA.

[State of DNA slots in mono- and oligonucleosomes and in DNA complexes with individual histones]. / Sostoianie borozdok DNK v mono- i oligonukleosomakh i v kompleksakh DNK s individual'nymi gistonami.

The state of the major and the minor DNA grooves in purified mono- and oligonucleosomes and in the complexes of DNA with different histones have been studied by means of methylation of DNA with dimethyl sulphate. In nucleosomes histones shielded major groove by 18--20%. This result agrees well with our previous data obtained with chromatin, nuclei and whole cells. Each of the purified histones H2a, H2b, H3 and H4 as well as N-terminal peptides of H4 histone cause relative shielding of the DNA major groove by 15--18% like whole histone does. H1 histone protects neither DNA grooves from methylation. Our results suggest that histones are buried partly in the major groove of DNA in chromatin and purified nucleosomes. The arrangement of histones in the major groove does not depend probably on their specific organization in nucleosomes.