Frequency-specific audiometry using steady-state responses

OBJECTIVE

To evaluate the audiometric usefulness of steady-state responses to multiple simultaneous tones, amplitude-modulated at 75 to 110 Hz.

DESIGN

Steady-state responses to multiple tones amplitude-modulated at different rates between 75 and 110 Hz and presented simultaneously were recorded at different intensities in normal adults, well babies, normal adults with simulated hearing loss, and adolescents with known hearing losses. Response thresholds were compared with behavioral thresholds.

RESULTS

In normal adults the thresholds for steady-state responses to tones of 0.5, 1, 2, and 4 kHz were 14 +/- 11, 12 +/- 11, 11 +/- 8, and 13 +/- 11 dB, respectively, above behavioral thresholds for air-conducted stimuli, and 11 +/- 5, 14 +/- 8, 9 +/- 8, and 10 +/- 10 dB above behavioral thresholds for bone-conducted stimuli. In well babies tested in a quiet environment, the thresholds were 45 +/- 13, 29 +/- 10, 26 +/- 8, and 29 +/- 10 dB SPL. In adolescents with known hearing losses, the steady-state responses thresholds predict behavioral thresholds with correlation coefficients (r) of 0.72, 0.70, 0.76, and 0.91 at 0.5, 1, 2, and 4 kHz, respectively.

CONCLUSION

Steady-state responses to tone amplitude-modulated at 75 to 110 Hz can be used for frequency-specific objective audiometry. The multiple-stimulus technique allows thresholds to be estimated for eight different stimuli at the same time.

Intercorrelations and sources of variability in three mutagenicity assays: a population-based study

The purpose of this study was to evaluate the intercorrelation between three genetic assays in 112 subjects. The group was pooled from two originally separate but homogeneous subgroups of 56 persons each. Procedures included assays for hprt mutant frequencies, micronuclei in human lymphocytes, and mutations at the glycophorin A (gpa) loci. We found no statistically significant or biologically important intercorrelations among the three biomarkers. We did, however, observe significant correlations between log(e) hprt mutant frequency and cloning efficiency (inverse correlation for these 2 variables), age and log(e) hprt mutant frequency, an inverse relationship between cloning efficiency and age, and an important differential sex effect favoring a greater micronuclei frequency in females than males. No significant correlations between the covariates of interest and glycophorin A variant frequencies NN or NO were observed. Using multivariable linear regression, age was found to account for the majority of the variability in hprt mutant frequency (greater than sex and/or smoking); for micronuclei data, only sex contributed a statistically significant and biologically important proportion to the total variation. We conclude that despite observing no significant intercorrelations between the three assays performed simultaneously from the same individuals in a large population database, a significant correlation between age and hprt mutant frequency and an inverse association between cloning efficiency and hprt do exist; furthermore, we verified the strong differential sex-specific effect on micronucleus frequencies.

[Unilateral asterixis and focal brain lesions. 12 cases]

Asterixis is a involuntary movement with spontaneous interruptions and intermittent muscle tone. It occurs during posture maintenance. It is usually bilateral and, in this case, is observed in metabolic encephalopathy. Unilateral asterixis is more uncommon. We report 12 cases which occurred in patients with focal brain lesions. In all cases asterixis involved the upper limb and the lower limb in only 2 cases. Asterixis was transient, discrete and always associated with other neurological signs. The causal lesions (7 infracts, 2 haematomas, 2 abscesses, 1 meningioma) were unique in 7 cases and multiple in 5. Asterixis was always contralateral to the unilateral lesions. Lesions mainly involved the thalamus (7 cases) and other structures (lenticular nucleus, frontal lobe, internal capsule, precentral regions and cerebellum). The frequency of thalamic involvement suggested dysfunction of the thalamo-cortical loop.

Do persons living near a uranium processing site have evidence of increased somatic cell gene mutations? A first study

The objective of this study was to examine if individuals living near a uranium processing site have greater mutagenic damage, as measured by three mutagenicity assays, compared with subjects unexposed to any nuclear facilities. The design was a cross-sectional exploratory analysis of 112 subjects; 56 volunteer residents were from within a 5-mile radius of the Fernald Uranium Processing site and 56 'control' subjects were from a geographically separate area unexposed to any known uranium emissions. The groups were constrained to be similar in age and sex composition. The main outcome measures were three human somatic gene mutation assays consisting of the HPRT T-lymphocyte cloning assay to measure 6-thioguanine resistant lymphocytes; the glycophorin A assay to detect the loss of expression of the M or N allele; and the micronucleus assay as a marker of chromosomal damage. The results showed no statistically significant or quantitatively important differences between groups for all three mutagenicity assays; only the unselected cloning efficiency was statistically significantly different between groups (0.42 +/- 0.16 for the Fernald versus 0.35 +/- 0.12 for the comparison groups). In both groups, age was significantly related to HPRT mutant frequency, with a 1.25% rate of increase in mutant frequencies for each 1-year gain of age in the Fernald group and a 1.12% rate of increase in mutant frequencies for each 1-year gain of age in the comparison group. For the micronucleus data, females had a greater mean micronucleus frequency than males. In addition, smokers had an increased mean ln (natural logarithm) HPRT mutant frequency (3.06 +/- 0.14 for current smokers compared with a mean of 2.72 +/- 0.05 for non-current (i.e. never plus former) smokers). Our results are consistent with the previously reported association between sex type and micronucleus frequency, the known relationship between age and T-lymphocyte cloning efficiency and age and HPRT mutant frequency, and verify the wide inter-subject variability for the latter. Finally, we conclude that at a population level, the relationships between current cigarette use and HPRT mutant frequency, and sex type and micronucleus frequency, are stronger than is the association between geographic proximity to a uranium processing site and mutagenic abnormalities.

Growth, induction, and substrate specificity of dehydroabietic acid-degrading bacteria isolated from a kraft mill effluent enrichment

We investigated resin acid degradation in five bacteria isolated from a bleach kraft mill effluent enrichment. All of the bacteria grew on dehydroabietic acid (DHA), a resin acid routinely detected in pulping effluents, or glycerol as the sole carbon source. None of the strains grew on acetate or methanol. Glycerol-grown, high-density, resting-cell suspensions were found to undergo a lag for 2 to 4 h before DHA degradation commenced, suggesting that this activity was inducible. This was further investigated by spiking similar cultures with tetracycline, a protein synthesis inhibitor, at various times during the DHA disappearance curve. Cultures to which the antibiotic was added prior to the lag did not degrade DHA. Those that were spiked with the antibiotic after the lag phase (4 h) degraded DHA at the same rate as did controls with no added tetracycline. Therefore, de novo protein synthesis was required for DHA biodegradation, confirming that this activity is inducible. The five strains were also evaluated for their ability to degrade other resin acids. All strains behaved in a similar fashion. Unchlorinated abietane-type resin acids (abietic acid, DHA, and 7-oxo-DHA) were completely degraded within 7 days, whereas pimarane resin acids (sandaracopimaric acid, isopimaric acid, and pimaric acid) were poorly degraded (25% or less). Chlorination of DHA affected biodegradation, with both 12,14-dichloro-DHA and 14-chloro-DHA showing resistance to degradation. However, 50 to 60% of the 12-chloro-DHA was consumed within the same period.

Genomic sequencing indicates a correlation between DNA hypomethylation in the 5' region of the pS2 gene and its expression in human breast cancer cell lines

The methylation status of the cytosines located on the 5' region of the pS2 gene have been investigated in two human breast cancer cell lines. The genomic sequencing method used is based on an oxydative deamination by NaHSO3 of the unmethylated cytosines, but not 5-methylcytosine. Data obtained indicate that in the DNA extracted from the pS2-expressing cell line, MCF7, the CpG located at the 5' flanking sequence of pS2 are unmethylated. In contrast in the non-expressing cell line, BT20, these CpG are largely methylated. However, this correlation is not observed at all CpG sites, since a significant portion of the cloned PCR fragments obtained from BT20 cells are unmethylated at specific CpG sites. These results suggest that the methylation status of only some of the CpG located at the 5' flanking sequences of pS2 might differ between expressing and nonexpressing cell lines.

Vascular ataxic hemiparesis: a re-evaluation

Ataxic hemiparesis is commonly considered as one of the "typical" lacunar syndromes. Using the prospective stroke registries from Lausanne and Besançon, 100 patients were selected consecutively (73% men, 27% women; age 64.7 (SD 13.6) years) with a first stroke and ataxic hemiparesis (hemiparesis or pyramidal signs and ipsilateral incoordination without sensory loss). Brain CT or MRI was performed on all patients. A primary haemorrhage was present in 5%, an infarct in 72%, isolated leukoaraiosis in 9%, and no apparent abnormality in 14%. The locations of lesions were the internal capsule (39%), pons (19%), thalamus (13%), corona radiata (13%), lentiform nucleus (8%), cerebellum (superior cerebellar artery territory) (4%), and frontal cortex (anterior cerebral artery territory) (4%). The clinical features of ataxic hemiparesis with different locations were almost identical. Only minor associated signs allowed the localisation of the lesions (paraesthesiae with a lesion in the thalamus; nystagmus or dysarthria with a cerebellar or pontine location). Crural paresis with homolateral ataxia was seen only with cortical paramedian frontal lesions. Presumed hypertensive small artery disease was not always found, but was still the leading cause of stroke, being present in 59% of the patients and in 62% of those with small deep infarcts. A potential source of embolism (arterial or cardiac) was found in one fourth of the patients. Therefore no definite association can be made between ataxic hemiparesis and lacunar infarction. In particular, so called uncommon lesion locations may not be rare. After extensive investigations a diagnosis of lacunar infarct can be retained in only slightly more than half of the cases.

Thrombin does not alter vascular hyporeactivity in models of endotoxin-induced septic shock in rats

1. Hypotension and vascular hyporesponsiveness to vasoconstrictors are observed during endotoxic shock, and are associated with increased production of nitric oxide in the vascular wall. Disseminated intravascular coagulation is another feature of septicaemia. We hypothesized that thrombin generated during disseminated intravascular coagulation might modulate the changes in vascular tone induced by endotoxin. 2. Incubation of rat aortic rings for 4 h with alpha-thrombin (0.003-3.0 NIH units/ml) did not change their reactivity to noradrenaline. Incubation for 4 h with lipopolysaccharide increased the EC50 for noradrenaline, whereas co-incubation of thrombin (0.5 NIH units/ml) with lipopolysaccharide did not alter this hyporeactivity to noradrenaline. 3. In vivo in rats, lipopolysaccharide caused early (1 h) and late (4-6 h) hyporeactivity to noradrenaline. In rats infused with lipopolysaccharide and heparin (1 U min-1 kg-1, 0.4 ml/h) or hirudin (2.2 mg ml-1 kg-1, 0.8 ml/h), vasopressor responses to noradrenaline were not different from those after infusion of lipopolysaccharide alone. Aortic rings taken from rats receiving both anticoagulant treatment and lipopolysaccharide had the same sensitivity to noradrenaline as those obtained from rats receiving lipopolysaccharide alone. 4. Our results suggest that, in vivo, disseminated intravascular coagulation does not modify the early and late effects of lipopolysaccharide on arterial pressure and that, in vitro, thrombin neither induces hyporeactivity to noradrenaline nor modifies lipopolysaccharide-induced hyporeactivity. We propose that thrombin generated during disseminated intravascular coagulation in rats does not play a major role in the alterations of vascular tone observed during endotoxic shock.

Patterns of injury in pediatric patients in one Florida community and implications for prevention programs

OBJECTIVES

To meet community needs, injury prevention programs for children should be based on an understanding of the patterns of different mechanisms of injury. This study was conducted by the staff of a level II pediatric trauma center to describe the patterns of injury in pediatric patients with traumatic injuries.

METHODS

We conducted a retrospective review of medical records of all 184 pediatric "trauma alert" patients seen during a 1-year period. The trauma alert status is assigned to children with serious injuries or when the mechanism of injury is severe. Data analysis used descriptive statistics.

RESULTS

Pedestrian-versus-automobile injuries were the most common and most severe injuries, followed in frequency by falls, motor vehicle occupant, and bicycle-versus-automobile injuries. Younger children tended to have injuries as a result of falls; school-age children were involved more often in pedestrian and bicycle injuries, and adolescents had more motor vehicle occupant injuries. Failure to use safety devices, such as helmets and seat belts, was a common finding.

DISCUSSION

Patterns of injury were similar to those described in national studies. An extensive helmet campaign directed at child bicyclists was developed as a result of the priorities generated from the study. Other community programs included bicycle rodeos and a mix-off of nonalcoholic beverages.

A strategy for helping a child with burn injuries to cope with reconstructive surgery

An account of the method used to minimise trauma in a young child undergoing tissue expansion

Human breast and colon cancers exhibit alterations of DNA methylation patterns at several DNA segments on chromosomes 11p and 17p

In breast and colon adenocarcinomas methylation patterns at CCGG sites of several loci located on the short arm of chromosome 11 were determined by Southern blot analysis. Results obtained indicate that all tumor samples (20/20) exhibit DNA methylation changes when compared to their normal counterparts. In colon tumors, gamma-globin gene is usually hypomethylated (9/10), whereas Ha-ras gene, which is located in the same region, retains an unmodified DNA methylation pattern. Hypomethylation of parathyroid hormone (5/10) and catalase genes (4/10) are also frequently detected in colon tumor specimens. For the catalase gene the region around exon 2 is the only one which is affected by these changes. In breast adenocarcinoma, modifications of the methylation patterns are less frequently observed. However, hypomethylation of the gamma-globin gene is a very common event in these tumors (8/10), and it is also detected (2/2) in lobular carcinoma in situ which is an early step in breast tumorigenesis. In addition, hypermethylation of a CpG island is also observed at the locus 17p13.3 in both colon (5/5) and breast (4/9) adenocarcinomas. In the tumoral tissues analyzed these hypermethylations are not associated with the hypermethylation of the 5' flanking sequences which contain a limited amount of CpG. Some of these alterations seem, therefore, to be tumor and sequence specific.

Expression of an estrogen-induced breast cancer-associated protein (pS2) in benign and malignant human ovarian cysts

BACKGROUND

In human mammary tumors, pS2 expression is directly controlled by estrogens and restricted to a subclass of breast carcinomas. In addition, recent studies have suggested that this gene is expressed in both the invasive and preinvasive forms of breast cancer.

EXPERIMENTAL DESIGN

pS2 gene expression was investigated in benign and malignant ovary tumors and whenever possible, pS2 expression was also studied in cells collected from cystadenoma fluids. In several cases, particularly with cells from cystadenoma fluids, the limited amount of material available prevented the used of the traditional RNA detection methods such slot/dot blots or Northern blots. Therefore, a rapid and sensitive polymerase chain reaction assay of pS2 expression has been developed and used in this study.

RESULTS

In human ovarian tumors, data obtained show that pS2 transcripts and proteins are present in all mucinous cystadenomas studied and at a lower frequency in endometrioid cystadenomas. Quantitation of the CA 19-9 mucin concentration in ovarian fluids indicate that pS2 expression is always associated with high mucin concentrations, but mucin-positive and pS2-negative samples are also frequently observed.

CONCLUSIONS

These data suggest that pS2 expression is restricted to subclasses of human ovarian cystadenomas.

Analysis of the B-cell progenitor compartment at the level of single cells

BACKGROUND

During B-cell development in the mouse, the VH, DH and JH elements of the immunoglobulin heavy chain (IgH) locus are rearranged, firstly by DH-JH joining, and then by VH-DHJH joining. In-frame ('productive') VHDHJH joints and DHJH joints in reading frame 2 (one of the three possible DH reading frames) allow the expression of mu and truncated mu chains (D mu proteins), respectively. The expression of such molecules from one of the two IgH loci of a cell is thought to interfere with VH-DHJH recombination on the other IgH locus, and to guide the cells through further development.

RESULTS

We have developed a gene amplification assay that permits the examination of rearranged immunoglobulin genes in single cells. Using this assay, we monitored cells bearing DHJH and/or VHDHJH joints at early stages of development: in CD43+ B-cell progenitors, subdivided into fractions A, B, C and C' by flow cytometry, and in CD43- pre-B cells (fraction D). Fraction C was enriched for cells with two non-productive VHDHJH joints. Cells containing both a DHJH joint in DH reading frame 2 and a VHDHJH joint were not seen in any fraction. All fraction D cells harbored an in-frame VHDHJH joint. Cells with two productive VHDHJH joints appear to be selected against throughout development.

CONCLUSIONS

Cells expressing D mu proteins appear to be arrested in development as a result of inhibited VH-DHJH joining. Expression of the mu chain is required for maturation into CD43- pre-B cells; accordingly, cells carrying two non-productive VHDHJH joints accumulate in the CD43+ compartment. Such a developmental arrest may also affect cells that express self-reactive VHDHJH antibody domains. Our results indicate further that allelic exclusion at the IgH locus is already established at the pre-B cell stage.

Designing a "healthy" diploma in management studies

Describes the range of issues considered in designing a programme of education and development for NHS managers. The programme took the form of a certificate and diploma in management studies with a very work-based approach using action learning sets and applied theory and techniques. Briefly discusses the recent history and debates in management education together with the tensions caused by academic focus on critical analysis and evaluation and the workplace focus of being effective and making improvements. This programme attempts to recognize and build on the strengths of both approaches and also to add some of the best practice from trainers' experience of designing personal development plans. Discusses the emphasis on reflective learning and the use of research-based assignments instead of conventional exams. Concludes with some indications of possible future developments from this model.

Hepatitis B vaccination in prisons: the Catalonian experience

A pilot programme of hepatitis B vaccination was set up in three prisons to assess the feasibility and results of this method of reaching a high-risk population. Hepatitis B vaccine was offered to all inmates who lacked serological markers for hepatitis B virus. The antibody response was assessed in those who received two or three doses of vaccine. Candidates for vaccination were 41% of 1755 imprisoned men (20% of intravenous drug users (IVDU) and 63% of non-IVDU), but complete vaccination could be given to only 33% of candidates. A further 29% received two doses. Seroconversion to anti-HBs (titres > 10 IU l-1) occurred in 33% of vaccinees after two doses and in 76% after three doses. The overall rate of susceptible inmates who became protected for hepatitis B was 34%. The seroconversion rate was higher when the interval between the first two doses was shorter than 3 weeks (91%), than in cases with an interval of 3-6 weeks (79%) or longer than 6 weeks (33%). Age greater than 35 years and history of IVDU were associated with a lower response to the vaccine, while anti-HIV seropositivity did not influence the response. In conclusion, vaccination of prisoners susceptible to HBV may achieve protection in at least a third of cases. Shortening intervals between the priming doses of vaccine may improve compliance and increases the response.

Overview of paclitaxel (TAXOL)

The history of development of paclitaxel (TAXOL [Bristol-Myers Squibb Co., Princeton, NJ]) is a long story and serves as a model of perseverance for those involved in drug development. Notations of the use of products of the yew tree date back to the Celts, but it was in the 1950s to the 1960s that the National Cancer Institute (NCI) selected the product for trials and the current process began. The active agent was identified in the 1970s, and when its unique mechanism of action was isolated in 1979, interest reemerged. Paclitaxel is an antimicrotubule agent that, unlike other antimicrotubule agents, promotes microtubule assembly. This unique mechanism of action has generated considerable interest in oncology. The clinical trials in the 1980s documented the drug's safety, identified its side effects, and demonstrated its activity in patients with ovarian cancer who had received prior treatment. The many clinical trials currently under way will provide information on the drug's range of activity. Paclitaxel's development has been an arduous process. Its development and supply initially were complicated, but these hurdles have been overcome, and the drug's unique mechanism of action and initial clinical trial results hold promise in the 1990s.

Comparative mammal model of chronic rate overload: relationship of myocardial Ca-cycling to heart, metabolic and lipoperoxidation rates

1. The cardiac cycle is generally believed to be timed by a sarcoplasmic Ca-cycle and powered by a sarcoplasmic ATP-cycle that uses fatty acids as fuel and generates toxic free radicals as a side-product. 2. This study used a comparative mammal approach to test this model and the hypothesis that these cycles were closely coupled and correlated with fatty acid oxidation and peroxidative injury. 3. Fatty acid oxidation and ATP-cycling rates correlated to log heart rate whereas Ca-cycling rate was directly coupled to heart rate in a one-to-one relationship. 4. Both Ca-pump and Ca-channel activities coordinately increased as heart rate increased across species. 5. Thus, Ca-cycling activity is constant across mammals, when normalized to heart rate. 6. Comparison of Ca-ATPase and Ca-flux rates indicated that sarcoplasmic volume was inversely correlated with log heart rate. Basal lipoperoxidation of myocardium and susceptibility of SR to lipoperoxidation correlated with metabolic rate. 7. We identified that the horse is a metabolic outlier amongst mammals, with abnormally high fatty acid oxidation and ATP-synthetase activity compared to its heart rate.

Pulmonary lymphangiomyomatosis causing bilateral pneumothorax during pregnancy

A 32-year-old woman, 12 weeks pregnant, presented with bilateral spontaneous pneumothorax that did not heal with tube thoracostomy. At right and left thoracotomy, lymphangiomyomatosis of the lung was found and treated by pleurodesis. Lymphangiomyomatosis has been infrequently reported in the surgical literature, even though it may befall the thoracic surgeon to establish the diagnosis and aid in treatment.