ABSTRACT
Plasmid pIP173, isolated from Salmonella ordonez strain BM2000, confers resistance to tetracycline and a number of other antibiotics. We determined the nucleotide sequence of the pIP173 tetR repressor and tetA resistance genes. The pIP173 tetR gene is essentially identical to the class D tetR gene from plasmid RA1. The pIP173 tet genes are flanked by directly repeated copies of the insertion sequence IS26. Interestingly, the 3' end of the tetR gene, encoding the C-terminal 16 amino acids of the TetR protein, extends into the flanking IS26 sequence. The relationships between the class A, B, C, and D TetA sequences parallel the relationships between the corresponding TetR sequences; class D is more closely related to class B than to either class A or C. Overall, the four TetA sequences show 38% identity and 57% similarity.
Subject(s)
Genes, Bacterial/genetics , R Factors/genetics , Repressor Proteins/genetics , Salmonella/genetics , Tetracycline Resistance/genetics , Amino Acid Sequence , Base Sequence , Chromosome Mapping , DNA Transposable Elements/genetics , Molecular Sequence Data , Plasmids/genetics , Sequence Homology, Amino AcidSubject(s)
Intraoperative Care , Portal Vein/injuries , Adult , Humans , Male , Portal Vein/surgery , Postoperative ComplicationsABSTRACT
Xenon-CT cerebral blood flow determinations in 20 children and young adults (age less than 40) who presented with cerebral ischemia were retrospectively reviewed for evidence of unifocal or multifocal ischemic disease. These results were compared with the findings of conventional CT and magnetic resonance (MR) examinations in the same patients. Xenon-CT revealed additional lesions or added significant pathophysiological information in 80% of patients scanned by noncontrast CT, 89% scanned by postcontrast CT, and 58% scanned by MR. Xenon-CT is a useful adjunct to MR and conventional CT in the evaluation of cerebral ischemia in children and young adults.
Subject(s)
Brain Ischemia/diagnosis , Cerebrovascular Circulation , Tomography, X-Ray Computed/methods , Xenon , Adolescent , Adult , Brain Ischemia/etiology , Brain Ischemia/physiopathology , Child , Child, Preschool , Female , Humans , Infant , Magnetic Resonance Imaging , Male , Retrospective StudiesABSTRACT
Computed tomography of the spine using intrathecal metrizamide was performed on six patients with spinal trauma. Dural tears with contrast material escaping outside the subarachnoid space were documented in five cases. In one case, the thecal laceration had healed and the contrast material was confined in a post-traumatic meningocele. The characteristics of dural tears are demonstrable by metrizamide computed tomography, either in conjunction with myelography or as a separate procedure. Neurological deficits following spinal trauma may be aggravated by dural tears with entrapment of the spinal nerve roots.
Subject(s)
Spinal Cord Injuries/diagnostic imaging , Spinal Injuries/diagnostic imaging , Tomography, X-Ray Computed , Adult , Child, Preschool , Female , Humans , Male , MetrizamideABSTRACT
Reversible transient osmotic blood-brain barrier disruption was used to increase drug delivery to the brain. Methotrexate was administered 33 times to six patients with brain tumors after barrier disruption. No permanent complications were seen. Serial enhanced computed tomographic (CT) scans and quantification by CT tomographic number indicated that disruption increased drug delivery to the tumor and immediate surrounding brain. Neuroradiologic evaluation showed that drug in the tumor persisted longer after barrier disruption than when delivered without disruption. The concentration of methotrexate in spinal fluid did not correlate with the degree of barrier disruption measured by CT and radionuclide scans. In one patient an anatomic variation in the circle of Willis resulted in barrier disruption extending into the posterior fossa without ill effect. Osmotic blood-brain barrier disruption appears to be a safe procedure in man, able to increase drug delivery to both malignant brain tumors and surrounding brain parenchyma.
Subject(s)
Blood-Brain Barrier/drug effects , Brain Neoplasms/drug therapy , Glioma/drug therapy , Methotrexate/administration & dosage , Brain/diagnostic imaging , Brain Neoplasms/diagnostic imaging , Glioma/diagnostic imaging , Humans , Mannitol , Methotrexate/metabolism , Methotrexate/therapeutic use , Tomography, X-Ray ComputedABSTRACT
Infusion of 25% mannitol in saline into the internal carotid artery of dogs disrupts the blood-brain barrier (BBB) in a controlled and reproducible manner (osmotic disruption), whereas mannitol infused through the common carotid artery produces variable disruption of the BBB. Compared to controls, infusion of methotrexate in dogs after osmotic disruption produced significantly higher drug levels in brain. We report very preliminary data on the effects of osmotic disruption with mannitol in five patients harboring malignant brain tumors.
Subject(s)
Blood-Brain Barrier/drug effects , Brain Neoplasms/drug therapy , Mannitol/administration & dosage , Methotrexate/administration & dosage , Animals , Dogs , Drug Evaluation , Functional Laterality , Humans , Infusions, Intra-Arterial , Kinetics , Mannitol/pharmacology , Osmolar ConcentrationABSTRACT
The blood-brain barrier seems to be an important factor in drug access to malignant brain tumors. Successful experimental reversible disruption of the blood-brain barrier in animals provided the basis for a clinical evaluation of osmotic disruption in five patients with primary and metastatic malignant brain tumors. Good to excellent blood-brain barrier disruption was achieved in four patients with a single nontransient complication, a superficial wound infection at the burr hole site in the first patient. Reversible, transient osmotic barrier disruption was achieved 15 times in five patients without additional toxicity. Computed tomography and radionuclide brain imaging were shown to be useful noninvasive monitors of the adequacy and extent of barrier disruption. These studies also provide further evidence that the barrier is at least partially intact in human tumors because in one patient a metastsis was seen only after barrier disruption.
