Effects of aging and caloric restriction on hepatic drug metabolizing enzymes in the Fischer 344 rat. I: The cytochrome P-450 dependent monooxygenase system.

The effects of long-term caloric restriction on the hepatic cytochrome P-450 dependent monooxygenase system were investigated in the 22-month-old Fischer 344 rat. Caloric restriction decreased the age-related changes in hepatic testosterone metabolism, which are associated with demasculinization of the liver. Caloric restriction also increased hepatic microsomal testosterone 6 beta-hydroxylase, lauric acid 12-hydroxylase and 4-nitrophenol hydroxylase activities over corresponding values in both ad libitum fed 22-month and 60-day-old control male rats. This suggests that cytochrome P-450 isozymes, P-450 pcn1&2, P-452 and P450j may be induced by caloric restriction. Such changes in cytochrome P-450 isozyme profiles could result in altered carcinogen activation, radical formation or drug detoxication in the calorically restricted rat.

Effects of aging and caloric restriction on hepatic drug metabolizing enzymes in the Fischer 344 rat. II: Effects on conjugating enzymes.

The effects of long-term caloric restriction on the hepatic phase II drug metabolizing enzymes were investigated in the male Fischer 344 rat. Rats that had been restricted to 60% of their pair-fed control consumption from 14 weeks post-partum exhibited altered conjugating enzyme activities at 22 months. Caloric restriction significantly reduced the age-related decrease in glutathione-S-transferase activity towards 1,2-dichloro-4-nitrobenzene, but did not significantly alter the age-related changes in UDP-glucuronyltransferase or sulfotransferase activities towards hydroxysteroids. Caloric restriction appeared to increase hepatic microsomal UDP-glucuronyltransferase activity toward bilirubin and gamma-glutamyltranspeptidase activities. These observations suggest that caloric restriction has multiple effects on the hepatic phase II drug metabolizing enzymes in the rat. Such effects may alter hepatic metabolism and activation or detoxification of drugs and carcinogens.

Effects of maternal diabetes on fetal expression of insulin-like growth factor and insulin-like growth factor binding protein mRNAs in the rat.

Maternal diabetes is associated in humans and rats with an increased risk for fetal growth abnormalities and malformations. Therefore, the effect of maternal diabetes on expression of genes that regulate fetal growth and differentiation is of considerable interest. Developmental growth is regulated in part by the expression and availability of insulin-like growth factors (IGFs). Postnatal expression of a subset of the IGFs and IGF binding proteins (IGFBPs) has been demonstrated to be regulated in response to diabetes and other metabolic conditions. We used in situ hybridization to analyze the effect of maternal diabetes, induced by streptozotocin (STZ) prior to mating, upon prenatal rat IGF and IGFBP mRNA expression. At gestational day (GD) 14, the most striking effect of maternal diabetes on fetal IGF/IGFBP gene expression was a marked increase in the abundance of IGFBP-1 mRNA within the liver primordia of fetuses isolated from diabetic dams compared to age-matched controls. This upregulation cannot be entirely due to the approximately one-half-day delay in fetal development (based on limb bud staging) associated with maternal diabetes, as there was no gross difference in the level of IGFBP-1 mRNA between GD13 and GD14 control fetal livers. In contrast, the fetal mRNA expression patterns of IGF-I, IGF-II and IGFBP-2, -3, -4, -5 and -6 were not grossly altered by maternal diabetes. These data are consistent with the hypothesis that IGFBP-1 produced within the fetal liver and secreted into fetal circulation may play a role in regulating rat fetal growth.

Maternal diabetes induces upregulation of hepatic insulin-like growth factor binding protein-1 MRNA expression, growth retardation and developmental delay at the same stage of rat fetal development.

Since maternal diabetes is associated with fetal growth abnormalities in humans and rats, effects of maternal diabetes on fetal expression of genes regulating growth are of interest. Increased expression of Insulin-Like Growth Factor Binding Protein-I (IGFBP-1) is associated with several examples of growth retardation and is upregulated in response to diabetes. As we have shown previously, IGFBP-1 expression is upregulated in gestational day (GD) 14 rat fetuses in response to maternal diabetes. Here we analyze the effect of streptozotocin-induced maternal diabetes on IGFBP-1 mRNA expression during GD12-16 of rat fetal development, using in situ hybridization. IGFBP-1 mRNA was more abundant in GD12-14 fetal livers from diabetic dams than in livers of age-matched controls. This upregulation is not due to the approximately 1-day fetal developmental delay associated with maternal diabetes, as there is no gross difference in the level of IGFBP-1 mRNA in GD13 vs GD12 or GD14 vs GD13 control fetal livers. At GD15-16, however, we detected little difference in IGFBP-1 expression between experimental and control fetuses. This transient period of maternal diabetes-stimulated IGFBP-1 mRNA expression (GD12-14) is coincident with the sensitive period for maternal diabetes-induced defects in fetal growth and development, suggesting that IGFBP-1 is involved in the regulation of fetal growth and development in response to the maternal condition.

Analysis of mutations and bone marrow micronuclei in Big Blue rats fed leucomalachite green.

Leucomalachite green (LMG) is the major metabolite of malachite green (MG), a triphenylmethane dye that has been used widely as an antifungal agent in the fish industry. Concern over MG and LMG is due to the potential for consumer exposure, suggestive evidence of tumor promotion in rodent liver, and suspicion of carcinogenicity based on structure-activity relationships. In order to evaluate the risks associated with exposure to LMG, female Big Blue rats were fed up to 543 ppm LMG; groups of these rats were killed after 4, 16, or 32 weeks of exposure and evaluated for genotoxicity. We previously reported that this treatment resulted in a dose-dependent induction of liver DNA adducts, and that the liver lacI mutant frequency (MF) was increased, but only in rats fed 543 ppm LMG for 16 weeks. In the present study, we report the results from lymphocyte Hprt mutant assays and bone marrow micronucleus assays performed on these same rats. In addition, we have determined the types of lacI mutations induced in the rats fed 543 ppm LMG for 16 weeks and the rats fed control diet. No significant increases in the frequency of micronuclei or Hprt mutants were observed for any of the doses or time points assayed. Molecular analysis of 80 liver lacI mutants from rats fed 543 ppm LMG for 16 weeks revealed that 21% (17/80) were clonal in origin and that most (55/63) of the independent mutations were base pair substitutions. The predominant type of mutation was G:C --> A:T transition (31/63) and the majority (68%) of these involved CpG sites. When corrected for clonality, the 16-week lacI mutation frequency (36 +/- 10) x 10(-6) in treated rats was not significantly different from the clonally corrected control frequency (17 +/- 9 x 10(-6); P = 0.06). Furthermore, the lacI mutational spectrum in treated rats was not significantly different from that found for control rats (P = 0.09). Taken together, these data indicate that the DNA adducts produced by LMG in female rats do not result in detectable levels of genotoxicity, and that the increase in lacI MF observed previously in the liver of treated rats may be due to the disproportionate expansion of spontaneous lacI mutations.

Mutagenicity and carcinogenicity in relation to DNA adduct formation in rats fed leucomalachite green.

Leucomalachite green is a persistent and prevalent metabolite of malachite green, a triphenylmethane dye that has been used widely as an antifungal agent in the fish industry. Concern over the use of malachite green is due to the potential for consumer exposure, evidence suggestive of tumor promotion in rodent liver, and suspicion of carcinogenicity based on structure-activity relationships. Our previous study indicated that feeding rodents malachite or leucomalachite green resulted in a dose-related increase in liver DNA adducts, and that, in general, exposure to leucomalachite green caused an increase in the number and severity of changes greater than was observed following exposure to malachite green. To characterize better the genotoxicity of leucomalachite green, female Big Blue rats were fed leucomalachite green at doses of 0, 9, 27, 91, 272, or 543 ppm for up to 32 weeks. The livers were analyzed for lacI mutations at 4, 16, and 32 weeks and DNA adducts at 4 weeks. Using a 32P-postlabeling assay, we observed a dose-related DNA adduct in the livers of rats fed 91, 272, and 543 ppm leucomalachite green. A approximately 3-fold increase in lacI mutant frequency was found in the livers of rats fed 543 ppm leucomalachite green for 16 weeks, but significant increases in mutant frequencies were not found for any of the other doses or time points assayed. We also conducted 2-year tumorigenesis bioassays in female and male F344 rats using 0, 91, 272, and 543 ppm leucomalachite green. Preliminary results indicate an increasing dose trend in lung adenomas in male rats treated with leucomalachite green, but no increase in the incidence of liver tumors in either sex of rat. These results suggest that the DNA adduct formed in the livers of rats fed leucomalachite green has little mutagenic or carcinogenic consequence.

Scoliosis in the Rett syndrome: natural history and treatment.

The Rett syndrome (RS) is associated with a neurological form of scoliosis. From 1985 we have instituted a postal survey of families with Rett girls. The prevalence of scoliosis in the survey population is 64%. The age at onset of scoliosis has a normal distribution about a peak age of 8 years, with 72% of cases occurring before age 8. The scoliosis in RS is typically a long thoracolumbar curvature that progresses rapidly in girls over the age of 10 years. Operative treatment is successful in reducing the curvature, preventing curve progression and improving spinal balance for sitting and walking. The 5 girls who walked pre-operatively are still able to do so.

Iliopsoas hematoma with femoral neuropathy presenting a diagnostic dilemma after spinal decompression.

STUDY DESIGN: Case report of an iliopsoas hematoma with femoral neuropathy appearing 8 weeks after a posterior spinal decompression procedure. OBJECTIVES: To describe a potential complication and differential diagnosis for nerve root symptoms following spinal decompression. SUMMARY OF BACKGROUND DATA: Iliopsoas hematoma is usually a complication of anticoagulation, hemophilia, or trauma. It has not been described previously as a complication of posterior spinal decompression. Femoral neuropathy results from compression within the iliopsoas compartment. METHODS: A 53-year-old woman reported pain in the right side of her groin and an increasing fixed flexion deformity of the right hip 8 weeks after a posterior, midline, spinal decompression. A femoral neuropathy later developed. Magnetic resonance imaging and computed tomography were performed. RESULTS: Imaging studies demonstrated a diffusely enlarged iliopsoas. Exploration revealed a large hematoma, which was evacuated. The compartment was fully decompressed with resolution of the nerve root symptoms within 48 hours. CONCLUSIONS: Iliopsoas pathology is a rare cause of nerve root symptoms and presented diagnostic difficulties after an apparently successful spinal decompression.

Delayed postoperative paraplegia with hypotension in adult revision scoliosis surgery.

The clear and reversible relationship of spinal cord function to postoperative hypotension is illustrated in a case of revision scoliosis surgery in an adult patient. The correlation of spinal cord monitoring by both magnetic cortical motor evoked potentials and spinal somatosensory evoked potentials to the clinical status is shown, and the importance of close postoperative observation of the adult revision case is emphasized.

Factors influencing the result of posterior spinal fusion in the treatment of adolescent idiopathic scoliosis.

Sixty-six consecutive patients with adolescent idiopathic scoliosis treated by posterior spinal fusion using Harrington distraction compression instrumentation were followed for a minimum of 3 years. Initial surgical correction was satisfactory, but during the follow-up period, mean 4.4 years (3-5 years), there was a loss of correction. Several factors (age, sex, the number of vertebrae in the fusions, and the use of cross wires) were important influences on correction. A method of assessing the balance of a posterior spinal fusion is described that is useful when assessing radiographs.

Observations on the growth of the adolescent spine.

We have measured the increase in height and width of the vertebral bodies and expressed them as percentages of the total growth in children aged 10 to 17 years. The first group, 10 boys and 10 girls, each had a single thoracic adolescent idiopathic scoliosis while the second group, 10 girls, each had a single lumbar adolescent idiopathic scoliosis. No significant differences were found between the growth increments and spinal dimensions of the vertebral bodies involved in the scoliotic curve and those vertebrae outside the curve in the same patient. The vertebrae were more slender in girls than in boys.

The Monk "soft top" endoprosthesis. Clinical, biomechanical and histopathological observations.

This paper presents a prospective trial carried out using the Monk "soft top" endoprosthesis in 33 patients. Two years after operation 70 per cent of the remaining patients had pain. A biomechanical and histopathological analysis of the endoprosthesis and the surrounding tissue, obtained from a further two patients at the time of revision, is presented. It is concluded that the prosthesis has inherent design faults which result in excessive wear of the polyethylene component. The wear debris produced stimulates a prolific fibrous tissue reaction which is associated with progressive clinical deterioration.

Scoliosis in neurofibromatosis. The natural history with and without operation.

We reviewed 47 patients with neurofibromatosis and dystrophic spinal deformities; 32 of these patients had been untreated for an average of 3.6 years and in them the natural history was studied. The commonest pattern of deformity at the time of presentation was a short angular thoracic scoliosis, but with progression the angle of kyphosis also increased. Deterioration during childhood was usual but its rate was variable. Severe dystrophic changes in the apical vertebrae and in particular anterior scalloping have a poor prognosis for deterioration. The dystrophic spinal deformity of neurofibromatosis requires early surgical stabilisation which should be by combined anterior and posterior fusion if there is an abnormal angle of kyphosis or severely dystrophic apical vertebrae. Some carefully selected patients can be treated by posterior fusion and instrumentation alone.

Spinal cord monitoring in scoliosis surgery. Experience with 1168 cases.

Since 1981, during operations for spinal deformity, we have routinely used electrophysiological monitoring of the spinal cord by the epidural measurement of somatosensory evoked potentials (SEPs) in response to stimulation of the posterior tibial nerve. We present the results in 1168 consecutive cases. Decreases in SEP amplitude of more than 50% occurred in 119 patients, of whom 32 had clinically detectable neurological changes postoperatively. In 35 cases the SEP amplitude was rapidly restored, either spontaneously or by repositioning of the recording electrode; they had no postoperative neurological changes. One patient had delayed onset of postoperative symptoms referrable to nerve root lesions without evidence of spinal cord involvement, but there were no false negative cases of intra-operative spinal cord damage. In 52 patients persistent, significant, SEP changes were noted without clinically detectable neurological sequelae. None of the many cases which showed falls in SEP amplitude of less than 50% experienced neurological problems. Neuromuscular scoliosis, the use of sublaminar wires, the magnitude of SEP decrement, and a limited or absent intra-operative recovery of SEP amplitude were identified as factors which increased the risk of postoperative neurological deficit.

An apparently new syndrome of bowed tibiae, radial anomalies, osteopenia, multiple fractures and developmental delay.

We report two siblings with bowed tibia, hypoplastic thumbs, multiple fractures, a distinctive facial phenotype and developmental delay. These children share some features with other cases reported in the literature but we consider that they represent a new syndrome.

Inadequacies of hospital medical records.

We have assessed the extent to which hospital records follow the Guidelines for Medical Records and Notes published by the Royal College of Surgeons of England. Notes of 100 consecutive discharges were reviewed from two surgical units, one at a District General Hospital (DGH) and the other at a London Teaching Hospital (TH). Overall, only 65 per cent (DGH) and 67 per cent (TH) of the entries specified by College guidelines were both present and correct. Substandard categories included the regular update of notes, post-operative instructions, comments about post-operative recovery, the record of advice given to relatives and incorrect consent. The guidelines produced by the Royal College of Surgeons are being applied, but there is room for considerable improvement. Inadequate medical records limit audit and may have medico-legal consequences. We recommend regular assessment of the standard of note keeping.