Studies on the Formation of 6-Hydroxydopamine in Mouse Brain After Administration of 2,4,5-Trihydroxyphenylalanine (6-HydroxyDOPA)

2,4,5-Trihydroxyphenylalanine (6-OH-DOPA) destroys central and peripheral noradrenergic neurons, while sparing dopaminergic neurons. Previous studies indicate that 6-OH-DOPA toxicity is mediated by the formation of 6-hydroxydopamine. However, levels of 6-hydroxydopamine in brain following peripheral administration of 6-OH-DOPA have not been documented. In the current study, 6-OH-DOPA and 6-hydroxydopamine were measured in brain by HPLC with electrochemical detection after intraperitoneal injection of 6-OH-DOPA. When mice were injected with 100 mg 6-OH-DOPA/kg, 6-hydroxydopamine levels in the striatum were highest (1.9 microgram/g) at 15 min and fell slowly to 24% of the peak value at 4 h. Experiments with reserpine indicated that the relatively stability of 6-hydroxydopamine was largely dependent upon storage in synaptic vesicles. Reserpine (10 mg/kg) lowered striatal 6-hydroxydopamine levels to 21.6% of control (non-reserpine-treated) values at 1 h, and to 8.9% of control values at 4 h. Levels of 6-hydroxydopamine in the striatum at 1 h were increased 113% by pargyline (100 mg/kg), 145% by alpha-methyldopahydrazine (carbidopa; 25 mg/kg), and 261% by pargyline and carbidopa together. Levels of dopamine in the striatum were unchanged at 2.5 h after 200 mg 6-OH-DOPA/kg (with pargyline and 50 mg carbidopa/kg), whereas levels of norepinephrine in the frontal cortex fell by 77%. At the same time, 6-hydroxydopamine levels were 8.8-fold higher in the striatum (5.54 micrograms/g) than in the cortex (0.63 micrograms/g).(ABSTRACT TRUNCATED AT 250 WORDS)     

Mutation of Bacillus firmus OF4 to duramycin resistance results in substantial replacement of membrane lipid phosphatidylethanolamine by its plasmalogen form.

Mutant strains of alkalophilic Bacillus firmus OF4 that were selected for resistance to duramycin had greatly reduced levels of membrane diacylphosphatidylethanolamine, as had been found in studies of such mutants of Bacillus subtilis. In the B. firmus strains, however, substantial levels of plasmenylethanolamine were found. This is an unusual membrane component for an aerobic eubacterium, but the presence of trace amounts even in the wild type was confirmed in experiments with 32Pi-labeled growth medium. The membrane lipid composition of the duramycin-resistant strains had several other changes that also left alkalophilic growth unimpaired.     

Involvement of integration host factor (IHF) in maintenance of plasmid pSC101 in Escherichia coli: characterization of pSC101 mutants that replicate in the absence of IHF

Escherichia coli mutants defective in the stable maintenance of plasmid pSC101 have been isolated following Tn10 insertion mutagenesis. One class of mutations affecting pSC101 replication was located in the genes himA and himD (hip), which encode the two subunits of integration host factor (IHF), a small histonelike DNA-binding protein that has multiple cellular functions. Mutants of pSC101 that could replicate in the absence of IHF were isolated and characterized; four independent mutational alterations were found to affect the third codon of the pSC101 rep gene, resulting in the replacement of glutamic acid by lysine. The compensating alteration appears to function by altering the activity of the pSC101 rep protein in him mutants.     

Serotonin in human lumbar cerebrospinal fluid: a reassessment

An inter-laboratory comparison study was carried out in order to ascertain mean levels of serotonin (5-HT) in human lumbar cerebrospinal fluid (CSF). Analyses were performed using high performance liquid chromatography (HPLC) coupled with either electrochemical (LC-EC) or fluorometric (LC-F) detection. With the detection limits obtained (7-8 pg/ml for LC-EC, 7-15 pg/ml for LC-F) 5-HT was not usually detected in human lumbar CSF. The findings indicate that the true mean concentration of CSF 5-HT is less than 10 pg/ml. This upper limit is substantially lower than all previous reports of 5-HT concentrations in normal human lumbar CSF. The extremely low concentrations of 5-HT present in CSF make it unlikely that CSF 5-HT will be of clinical utility in assessing central serotonergic function.     

Reconstruction of late craniofacial deformities after irradiation of the head and face during childhood

Little is known about the results of surgical management of late craniofacial abnormalities arising after irradiation of the head and face for treatment of childhood cancers. The clinical records of 10 children (4 males and 6 females) who received 4500 to 6500 rads (mean 5160 rads) of craniofacial radiation between birth and 8 years of age (mean 5 years) and who subsequently had reconstructive surgery were reviewed. Six of the 10 patients received orbital radiation, 3 received maxillary-midfacial radiation, and 1 patient underwent radiation to the frontal bone. Histologic tumor types included retinoblastoma (4), rhabdomyosarcoma (3), Ewing's sarcoma (2), and neurofibrosarcoma (1). In addition to radiation, 7 of the 10 patients underwent surgical resection or debulking of their tumors and 6 received adjuvant chemotherapy. All patients presented from 4 to 20 years after treatment (mean 10 years) with varying, but severe degrees of soft-tissue and bony hypoplasia of the irradiated territories. Onlay bone grafting with soft-tissue reconstruction by a combination of local pedicle flaps and dermal-fat grafts was initially performed in 9 patients, and an occipitoparietal bone-flap switch procedure was done in 1 patient. Late follow-up ranged from 11 months to 7.5 years (mean 34 months). A total of 8 secondary procedures were necessary in 4 of the 10 patients (40 percent). Of these 4 patients, major revisions were performed in 3 and minor adjustments in 1. In addition, 2 patients in whom secondary procedures had not been done would benefit from further reconstruction. Therapy for cancer of the head and face during childhood has profound and ongoing effects on the growth of soft tissue and bone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Role of DNA superhelicity in partitioning of the pSC101 plasmid

Previous work has shown that a cis-acting locus (termed par for partitioning) on the pSC101 plasmid accomplishes its stable inheritance in dividing cell populations. We report here that the DNA of pSC101 derivatives lacking the par region shows a decrease in overall superhelical density as compared with DNA of wild-type pSC101. Chemicals and bacterial mutations that reduce negative DNA supercoiling increase the rate of loss of par plasmids and convert normally stable plasmids that have minimal par region deletions into unstable replicons. topA gene mutations, which increase negative DNA supercoiling, reverse the instability of partition-defective plasmids that utilize the pSC101, p15A, F, or oriC replication systems. Our observations show that the extent of negative supercoiling of plasmid DNA has major effects on the plasmid's inheritance and suggest a mechanism by which the pSC101 par region may exert its stabilizing effects.     

Low density lipoprotein inhibits accumulation of nitrites in murine brain endothelial cell cultures.

Endothelial cells produce nitric oxide which is considered to serve as a major source of endothelial derived relaxing factor activity. It has been demonstrated that activation of mouse brain endothelium by TNF-alpha and IFN-gamma led to accumulation of nitrite which is presumably formed by oxidation of nitric oxide. A number of studies suggest that reactive oxygen species produced by cytokine-activated cells are involved in the conversion of nitric oxide to nitrites and nitrates. We investigated whether low density lipoprotein (LDL), acting as a radical scavenger, is able to inhibit nitrite accumulation in mouse brain endothelial cell cultures and in a cell-free system in which sodium nitroprusside was used as a source of nitric oxide. A comparison of these two models indicates the active involvement of LDL in suppressing nitrite accumulation in murine endothelial cultures.     

A comparison of fertilization envelope development in three species of Strongylocentrotus (S. franciscanus, S. droebachiensis, and S. purpuratus)

The ultrastructure of fertilization envelope (FE) development and the polypeptide spectra of Strongylocentrotus franciscanus and S. droebachiensis envelopes were compared to S. purpuratus. In S. franciscanus, the FE reached its maximum thickness of 67 nm by 3 minutes postinsemination (PI), and final structuralization was observed by 40 minutes PI. The fully formed FE did not have microvillar impressions (casts) and was symmetrical, with outer double laminar elements surrounding an amorphous central region. Isolated S. franciscanus FEs were soluble in reducing and denaturing solvents and the same set of 33 polypeptides ranging from 18.5 to 260 kD was detected in FEs isolated from 10 to 180 minutes PI. The S. droebachiensis FE retained microvillar casts, assumed its definitive form by 3 minutes PI, and was 70 nm thick between microvillar impressions. Isolated S. droebachiensis FEs were partially soluble in reducing and denaturing solvents, and the polypeptide spectra of FEs isolated between 10 and 60 minutes PI were identical and showed 14 polypeptides from 18.5 to 265 kD. Antisera against extracted FEs and the FE extract from S. purpuratus were immunologically cross-reactive (using an enzyme-linked immunosorbent assay) with S. franciscanus and S. droebachiensis FE preparations; immunoblots identified 13 and 5 cross-reactive polypeptides, respectively. Most of the cross-reactive polypeptides were of slightly different molecular weight. Based on comparative ultrastructural, solubility, and electrophoretic data, we suggest that S. droebachiensis FE development is most like that observed in S. purpuratus.