Molecular genetics and the initiation of solventogenesis in Clostridium beijerinckii (formerly Clostridium acetobutylicum) NCIMB 8052

A physical map of the Clostridium beijerinckii (formerly Clostridium acetobutylicum) NCIMB 8052 chromosome has been constructed, encompassing about 90 rare restriction sites. The 14 rrn operons together with about 40 genes have been assigned positions on the map. Genetic analysis and gene transfer have been developed in this organism to enable in vivo analysis of the roles of cloned genes using marker replacement technology. Experiments using the available genetic tools have shown that spo0A plays a cardinal role in controlling several aspects of the transition from exponential growth to stationary phase in C. beijerinckii. These include initiation of sporulation, accumulation of the storage polysaccharide, granulose, and production of acetone and butanol. Several C. beijerinckii and C. acetobutylicum genes concerned with fermentative metabolism, whose expression is modulated at the onset of solventogenesis, contain sequence motifs resembling 0A boxes in their 5' regulatory regions. This invites the speculation that they are under the direct control of Spo0A, and additional data are now required to test this prediction.

Factor VIII gene inversions in severe hemophilia A: results of an international consortium study

Twenty-two molecular diagnostic laboratories from 14 countries participated in a consortium study to estimate the impact of Factor VIII gene inversions in severe hemophilia A. A total of 2,093 patients with severe hemophilia A were studied; of those, 740 (35%) had a type 1 (distal) factor VIII inversion, and 140 (7%) showed a type 2 (proximal) inversion. In 25 cases, the molecular analysis showed additional abnormal or polymorphic patterns. Ninety-eight percent of 532 mothers of patients with inversions were carriers of the abnormal factor VIII gene; when only mothers of nonfamilial cases were studied, 9 de novo inversions in maternal germ cells were observed among 225 cases (approximately 1 de novo maternal origin of the inversion in 25 mothers of sporadic cases). When the maternal grandparental origin was examined, the inversions occurred de novo in male germ cells in 69 cases and female germ cells in 1 case. The presence of factor VIII inversions is not a major predisposing factor for the development of factor VIII inhibitors; however, slightly more patients with severe hemophilia A and factor VIII inversions develop inhibitors (130 of 642 [20%]) than patients with severe hemophilia A without inversions (131 of 821 [16%]).

Histogenesis of papillomas of the nose and paranasal sinuses

OBJECTIVE

To determine by review of their histogenesis whether papillomas of the nose and paranasal sinuses are three distinct entities or, as has been favored in the literature, three variations of a single entity.

METHODS AND PATIENTS

We examined biopsy sections from 191 patients with sinonasal papillomas. Biopsy sections included all types of sinonasal papillomas stained using routine methods and, in some cases, using immunohistochemistry for macrophages (PG-M1) and proliferation antigen (MIB-1). Two cases of inverted papilloma were also examined using transmission electron microscopy.

RESULTS

Everted and cylindric cell papillomas are true papillomas, lined by stratified squamous and microcystladen, columnar, oncocytic epithelium, respectively. Inverted papillomas are polyps with marked, patchy squamous metaplasia and numerous microcysts containing macrophages in ductal and surface epithelium. There are no intermediate forms from any one of the three types to another.

CONCLUSIONS

Some differences between the three types are already established with regard to sites of origin, tendency to recur, and association with malignancy. It is likely that their etiologies--eg, concerning human papillomavirus infection--will be found to differ, if their distinct histogeneses are considered.

Postneonatal screening for congenital syphilis

The incidence of congenital syphilis has recently reached epidemic proportions. With the resurgence of this important clinical entity, currently recommended screening procedures may be inadequate. We describe three cases that highlight the limitations of these screening procedures. All these infants had associated maternal risk factors for congenital syphilis, such as poor prenatal care and illicit drug use. All the infants and mothers were seronegative for syphilis at the time of birth but the infants became seropositive at 2 months of age. These cases support the need to reexamine current screening policies. In addition to prenatal and at-delivery screenings for congenital syphilis, it may be appropriate to screen infants born to high-risk mothers at 4 to 8 weeks of age.

New directions for assessing speech perception in persons with sensory aids

This study examined the influence of stimulus variability and lexical difficulty on the speech perception performance of adults who used either multichannel cochlear implants or conventional hearing aids. The effects of stimulus variability were examined by comparing word identification in single-talker versus multiple-talker conditions. Lexical effects were assessed by comparing recognition of "easy" words (ie, words that occur frequently and have few phonemically similar words, or neighbors) with "hard" words (ie, words with the opposite lexical characteristics). Word recognition performance was assessed in either closed- or open-set response formats. The results demonstrated that both stimulus variability and lexical difficulty influenced word recognition performance. Identification scores were poorer in the multiple-talker than in the single-talker conditions. Also, scores for lexically "easy" items were better than those for "hard" items. The effects of stimulus variability were not evident when a closed-set response format was employed.

Fatal systemic amyloidosis (AA type) in two sisters with dystrophic epidermolysis bullosa

Systemic amyloidosis is a rare but recognized complication of dystrophic epidermolysis bullosa. We report the cases of two siblings with recessive dystrophic epidermolysis bullosa who died of complications associated with systemic amyloidosis (AA type). This is the first report of systemic amyloidosis in siblings with dystrophic epidermolysis bullosa.

The expression of antisense and ribozyme genes targeting citrus exocortis viroid in transgenic plants

Four ribozyme and antisense genes targeting citrus exocortis viroid (CEVd) positive- and negative-strand RNA molecules were constructed and used to transform the tomato Lycopersicon lycopersicum cv. UC82B. The tomato is a readily transformable plant and will support replication of CEVd following mechanical inoculation. The ribozyme genes contained three hammerhead catalytic motifs with long hybridizing arms and synthetic RNA transcripts were shown to cleave the target CEVd RNA molecule in vitro. Homozygous transgenic plants were produced from independent transformants expressing either ribozymes or antisense constructs. Inoculation of transgenic seedlings expressing antisense constructs targeting the negative-strand CEVd RNA molecule with CEVd resulted in a moderate reduction in the accumulation of CEVd RNA. In contrast, similarly inoculated transgenic plants expressing constructs targeting the positive-strand CEVd RNA molecule resulted in an increase in the rate of CEVd RNA accumulation. Addition of the ribozyme motifs to the antisense genes did not enhance their efficiency in the suppression of viroid replication and a moderation or elimination of the observed antisense effects was seen in plants expressing the corresponding catalytic RNA-encoding genes.

The effects of Dynavision rehabilitation on behind-the-wheel driving ability and selected psychomotor abilities of persons after stroke

OBJECTIVE

Many conventional rehabilitation exercises, such as pencil-and-paper and computer tasks, may not train perceptual and motor skills as applied to a complex, multiskill activity such as driving. The present study examined the usefulness of the Dynavision apparatus for driving-related rehabilitation. The Dynavision was designed to train visual scanning, peripheral visual awareness, visual attention, and visual-motor reaction time across a broad, active visual field.

METHOD

Ten persons with a cerebrovascular accident participated in the study. All had failed behind-the-wheel driving assessments. Subjects participated in a 6-week Dynavision training program using exercises designed to impose various motor, perceptual, and cognitive demands.

RESULTS

Dynavision training resulted in significantly improved behind-the-wheel driving assessments as compared to expected outcomes. Comparisons between pretests, posttests, and follow-up tests on a number of Dynavision, response, and reaction time variables showed significant improvements and maintenance effects. Dynavision performance, and, to a lesser extent, choice visual reaction and response times, were found to differentiate between persons assessed as safe and unsafe to drive, and between older and younger drivers. Subject self-reports suggested that a variety of training-related improvements had occurred in everyday functioning.

CONCLUSION

Dynavision training shows some rehabilitative promise for improving driving and basic psychomotor skills. Future research on the benefits and limitations of this apparatus should use finer laboratory skill measures and more comprehensive tests of driving and daily functioning to assess more thoroughly skill improvements in persons after stroke.

TLC of p-nitroanilines and their analogues with cyclodextrins in the mobile phase

The addition of alpha-, beta-, gamma-, and hydroxypropyl-beta-cyclodextrins to aqueous mobile phases can be used to enhance the migration of p-nitroanilines and their analogues on thin-layer chromatography. Urea, which is used to solubilize the cyclodextrins in aqueous solutions, is also found to increase the migration of these compounds. The equilibrium binding constants for the solute-cyclodextrin complexes formed in the mobile phase are determined. The results obtained using either silica gel or polyamide plates are similar.

Morbidity and mortality of infants born before arrival at the hospital

Recently, a number of infants have been born at home, in an ambulance, car, etc., before arrival at the District of Columbia General Hospital. Many of these infants had poor outcome. To evaluate the prevalence and outcome of these infants, we reviewed medical records of all infants born before arrival at the hospital (out-born infants) and compared them with in-hospital deliveries from July 1988 to June 1992. Data were analyzed using Fisher's Exact Test and chi-square test. There were 151 (1.8%) out-born infants and 8,169 (98.2%) in-born infants during this 4-year period. Infants in both groups were predominantly black (85%). The following were significant differences (P < 0.001) between out-born and in-hospital deliveries, respectively: illicit drug exposure 35% vs 21%; low-birth-weight (< 2,500 g) infants 39% vs 16%; intensive care unit admissions 29% vs 15%; and neonatal deaths per 1,000 live births 80 vs 7. We conclude that there is a twofold increase in the morbidity (required intensive care) and an 11-fold increase in the mortality among out-born infants compared with infants delivered in-hospital. Even though out-born infants were < 2% of the total deliveries, they accounted for 17% of total neonatal mortality.

Hypogammaglobulinaemia secondary to reflux oesophagitis

A 7 year old girl referred for investigation of hypogammaglobulinaemia had hypoalbuminaemia and severe necrotising oesophagitis on oesophagogastroduodenoscopy. Nissen fundoplication resolved all clinical and laboratory abnormalities, but she remains under surveillance because of histological findings of Barrett's oesophagus. Erosive reflux oesophagitis can present with minimal localising symptoms, and hypogammaglobulinaemia and hypoalbuminaemia, presumably from protein loss.

Measurement and modeling of depth cue combination: in defense of weak fusion

Various visual cues provide information about depth and shape in a scene. When several of these cues are simultaneously available in a single location in the scene, the visual system attempts to combine them. In this paper, we discuss three key issues relevant to the experimental analysis of depth cue combination in human vision: cue promotion, dynamic weighting of cues, and robustness of cue combination. We review recent psychophysical studies of human depth cue combination in light of these issues. We organize the discussion and review as the development of a model of the depth cue combination process termed modified weak fusion (MWF). We relate the MWF framework to Bayesian theories of cue combination. We argue that the MWF model is consistent with previous experimental results and is a parsimonious summary of these results. While the MWF model is motivated by normative considerations, it is primarily intended to guide experimental analysis of depth cue combination in human vision. We describe experimental methods, analogous to perturbation analysis, that permit us to analyze depth cue combination in novel ways. In particular these methods allow us to investigate the key issues we have raised. We summarize recent experimental tests of the MWF framework that use these methods.

Adrenal steroids and cardiac fibrosis

Uninephrectomized rats maintained on 0.9% NaCl as drinking fluid and infused for 8 weeks with aldosterone 0.75 micrograms/h via subcutaneous osmotic minipumps respond with hypertension, cardiac hypertrophy, and both interstitial and perivascular cardiac fibrosis. Similar animals injected with desoxycorticosterone (20 mg/week), or the glucocorticoid antagonist RU 486 (2 mg/day) show interstitial cardiac fibrosis to a lesser degree than animals injected with aldosterone, and show perivascular fibrosis to a greater degree. These findings suggest that glucocorticoid antagonist activity may play a role in exacerbating perivascular collagen deposition in response to chronic mineralocorticoid and salt imbalance.

Physical map of the Clostridium beijerinckii (formerly Clostridium acetobutylicum) NCIMB 8052 chromosome

A combined physical and genetic map of the single, circular, 6.7-Mbp chromosome of the NCIMB 8052 strain of Clostridium beijerinckii (formerly Clostridium acetobutylicum) has been constructed by using a combination of cloned DNA fragments as hybridization probes and a bank of strains harboring insertions of the conjugative transposon Tn1545. The positions of 81 restriction endonuclease cleavage sites and 32 genes have been determined. Eight genes concerned with solventogenic fermentation are found at three different locations. The chromosome contains at least 13 rrn operons, 11 of which have been located on the map. Their transcriptional orientation diverges from the presumed location of the replication origin.

A visual inspection protocol for measuring characteristics of used syringes

This article reports on the use of a Visual Inspection Protocol (VIP) to measure observable characteristics of syringes deposited at the San Francisco needle exchange program. Syringes received by the program were evaluated by several inspectors using the VIP, and interrater reliability was assessed for each item. In Study I, syringes bearing individual markings made by the user (n = 568) were more likely to be capped at the point end and plunger end, and more often were new in appearance when compared with unmarked syringes (n = 2,820). In Study II, syringes with a short street life (n = 250) were more often new in appearance and were less likely to contain blood than syringes with a long street life (n = 246). Syringes having individual markings also show signs of more careful use, and marking syringes may represent an ad hoc HIV prevention strategy for some injection drug users.

Interobserver variability in the interpretation of chest roentgenograms of patients with possible pneumonia

BACKGROUND

Previous studies have found considerable interobserver variability in the roentgenographic diagnosis of pneumonia. In this study we determined the impact of experience on interobserver variability in the interpretation of chest roentgenograms of patients with pneumonia and defined the characteristics of chest roentgenograms interpreted as pneumonia by all groups.

METHODS

The chest roentgenograms of 15 consecutive patients with a clinical and roentgenographic diagnosis of pneumonia were read by a convenience sample of 10 first-year and 20 fourth-year medical students, 21 medical residents, and 21 staff physicians from the department of medicine. Three board-certified radiologists served as the gold standard. The majority rule decision and logistic regression analysis were used to analyze agreement among the various groups of observers.

RESULTS

Agreement with the majority decisions of the gold-standard radiologists on the presence or absence of pneumonia for all observations of the various groups were as follows: original radiologist, 87%; first-year medical students, 59%; fourth-year medical students, 54%; medical residents, 66%; and attending staff, 72%. Chest roentgenograms with dense lobar or segmental opacities were generally interpreted as pneumonia by all observers. Patchy opacities caused major disagreements and were usually read as not being due to pneumonia. Bronchopneumonia was not diagnosed by any of the observers. Air bronchograms, atelectasis, and chronic obstructive lung disease were usually not recognized by the nonradiologists.

CONCLUSIONS

There is considerable interobserver variability in the roentgenographic diagnosis of pneumonia. This variability does not improve with increasing experience. Dense lobar or segmental opacities are uniformly recognized as pneumonia while patchy opacities result in a variety of interpretations.