Ocular Hypertension and Corneal Thickness: A Long-Term Prospective Study. Results after Two Years

Purpose

To study the importance of the central corneal thickness (CCT) in patients with ocular hypertension in a 2-year follow-up.

Methods

A total of 110 subjects with ocular hypertension (intraocular pressure [IOP] >21 mmHg and normal automated visual field test) were admitted to the study. All patients periodically underwent the following tests: 1) circadian IOP curve; 2) standard automated perimetry (SAP, Humphrey 30–2 SITA test); 3) short wavelength automated perimetry (SWAP); 4) frequency doubling technology perimetry (FDT, N-30 threshold test); 5) nerve fiber layer analysis with GDx; 6) ibopamine test; 7) ultrasonic pachymetry. Patients were divided into three groups, based on corneal thickness. The frequency of abnormal tests within these groups was evaluated with the Pearson's χ2 test. Baseline IOP was corrected using the Doughty and Zaman formula. CCT was also considered as a continuous variable. A control group of 48 normal subjects was also considered.

Results

The mean CCT was 562.8 um ± 37.7. The difference with respect to normal subjects was statistically significant (p<0.01). Using the correction formula, 43 eyes (39.1%) had an IOP <21 mmHg. Abnormal test results were more frequently found with FDT. The percentage of abnormal results was found to be inversely proportional to CCT. The other tests gave inconsistent or conflicting results. Using the values of CCT as a continuous variable, no significant association was found with the GDx number and the visual field indices.

Conclusions

The results of our 2-year study confirm the importance of CCT measurement in the evaluation of the risk of developing glaucomatous damage.

Levodopa/carbidopa intestinal gel infusion in advanced Parkinson's disease: a 7-year experience

BACKGROUND AND PURPOSE

Levodopa/carbidopa intestinal gel (LCIG) infusion is nowadays becoming an established therapeutic option for advanced Parkinson's disease (PD) patients with fluctuating symptoms unresponsive to conventional oral treatment. As the implementation of LCIG therapy is increasing, there is a need for safety and efficacy data from current clinical practice.

METHODS

All PD patients treated with LCIG at our centre over a 7-year period were analysed to determine the duration of treatment, retention rate, reasons for discontinuation, LCIG efficacy in motor complications, modifications of concomitant therapy and adverse events.

RESULTS

Of the 59 patients, seven subjects (12%) died of causes unrelated to LCIG infusion and 11 patients (19%) discontinued therapy prior to the cut-off date. Duodopa improved motor complications and over 90% of patients reported an improvement in their quality of life, autonomy and clinical global status. The most common adverse events were dislocation and kinking of the intestinal tube.

CONCLUSIONS

LCIG infusion is effective for the long-term treatment of advanced PD patients and exerts a positive and clinically significant effect on motor complications with a relatively low dropout rate.

Sleep improvement with levodopa/carbidopa intestinal gel infusion in Parkinson disease

BACKGROUND

Sleep disorders are common in patients with advanced Parkinson's disease (PD). Nocturnal akinesia and sleep fragmentation frequently coexist with daytime sleepiness, influencing daytime functioning. Levodopa/carbidopa intestinal gel (LCIG) infusion has been shown to improve motor complications in advanced PD, and preliminary findings suggest that sleep might improve following LCIG infusion.

OBJECTIVE

To analyze the impact of LCIG infusion on sleep symptoms and daytime sleepiness in patients with PD.

METHODS

Twelve consecutive patients with PD completed the PD-Sleep-Scale-version-2 (PDSS-2) and the Epworth-Sleepiness-Scale (ESS) at baseline and after 2-4 months of LCIG treatment. Activities of daily living, motor symptoms and complications were assessed with the Unified-PD-rating-Scale section II, III, and IV.

RESULTS

Nocturnal sleep improved substantially in all patients switched to LCIG infusion. PDSS-2 total score and subscores for 'Disturbed sleep', 'Motor symptoms at night', and 'PD symptoms at night' were significantly reduced. ESS measures of daytime sleepiness also improved. Motor complications and activities of daily living improved significantly with LCIG.

CONCLUSION

Subjective measures of sleep quality and daytime sleepiness improve in patients with advanced PD undergoing LCIG infusion. Further studies with a larger number of patients and polysomnographic recordings are needed to confirm the beneficial effect on sleep and clarify the underlying mechanisms.

Hawking radiation from ultrashort laser pulse filaments

Event horizons of astrophysical black holes and gravitational analogues have been predicted to excite the quantum vacuum and give rise to the emission of quanta, known as Hawking radiation. We experimentally create such a gravitational analogue using ultrashort laser pulse filaments and our measurements demonstrate a spontaneous emission of photons that confirms theoretical predictions.

Apathy and verbal fluency in STN-stimulated PD patients

OBJECTIVE

To evaluate apathy and its relation to verbal fluency tasks in a consecutive series of 19 patients with Parkinson's disease (PD) submitted to deep brain stimulation of the subthalamic nucleus (DBS of STN).

METHODS

19 consecutive PD patients submitted to bilateral DBS of STN were studied for apathy pre-operatively and 17 months after surgery. The PD patients underwent a battery of cognitive tests assessing reasoning, memory and frontal executive functions, including phonemic and categorial fluency tasks. The Beck Depression Inventory (BDI) was used for depression. Apathy was assessed by means of the Apathy Scale (AS). In order to quantify changes among individual patients, the clinical criterion of more or less than 1 SD (standard z-score) was used to register a patient as improved or worsened, respectively.

RESULTS

After surgery, apathy scores did not change and mood improved (p < 0.02), while a significant worsening was found in the phonemic fluency (p < 0.001). The percentage of patients with an apathy score above the recommended cut-off value (14) was 42% both before and after DBS of STN. Individual outcomes on the apathy scale (1 SD criterion) evidenced that 53% of the patients remained stable, 16% improved, while 31% worsened. This last percentage reduced to 21% (4/19) when considering only the PD patients with an apathy score > or =14 after surgery. No significant correlation was found between the apathy scores variation and any of the neurological variables considered, and, in particular, no correlation was found between apathy and verbal fluency.

CONCLUSIONS

The results of the present study suggest that DBS of STN does not necessarily induce apathy even if individual patients show a moderate post-operative worsening of apathetic symptoms.

A structure-activity study for the inhibition of metalloproteinase-9 activity and gene expression by analogues of gallocatechin-3-gallate

Catechins are able to modulate the gelatinolytic activity of matrix metalloproteinase-9 (MMP-9) by reducing its release from macrophages. Gallocatechins decrease MMP-9 secretion by lowering MMP-9 promoter activity and mRNA levels. The effect appears to be dependent on some structural and stereochemical requirements. In this study, the relationship between chemical structure and activity was studied by testing the effect of analogues of (+/-)-gallocatechin-3-gallate (+/-)-GCG, selectively deprived of hydroxyl groups, on MMP-9 activity, transcription, and secretion. Our results indicate that (+/-)-GCG and (+/-)-catechin-3-gallate are characterized by a substitution pattern compatible with direct inhibition of MMP-9 activity. Conversely, when transcription was the target, (+/-)-trans-3-flavanol-3-benzoate, lacking all the hydroxyl groups, was the most effective both in lowering MMP-9 promoter activity and consequently protein secretion, and in inhibiting nuclear-factor-kappaB-driven transcription. Our results suggest that the structural requirements for enzyme inhibition are different from those necessary for targeting gene expression.

Mannanoligosaccharides and aflatoxin B1 in feed for laying hens: effects on egg quality, aflatoxins B1 and M1 residues in eggs, and aflatoxin B1 levels in liver

Ninety-six laying hens were allocated to 4 groups and fed diets (control diet (0-0), diet supplemented with 2.5 ppm aflatoxin B1 (0-AF); diet supplemented with 0.11% mannanoligosaccharide (MOS-0); diet supplemented with 0.11% MOS and 2.5 ppm aflatoxin B1 (MOS-AF) for 4 wk to evaluate the effect of aflatoxin B1 (AFB1), mannanoligosaccharide (MOS), or both on egg quality and the in vivo efficacy of MOS to interact with an oral administration of AFB1. After 2 and 3 wk, egg weight decreased (P < 0.05) in the group fed MOS-0 versus groups on 0-0 and 0-AF. Egg shell weight was lower (P < 0.05) in the group fed 0-AF. Aflatoxin influenced color parameters, which were probably related to interference of AFB1 with lipid metabolism and pigmentary substances deposition in yolk. MOS appeared to increase protein percentage in albumen. No AFB1 or aflatoxin M1 (AFM1; a polar metabolite of AFB1) residues were found in eggs of the experimental groups. Livers from groups 0-0 and MOS-0 always tested negative for AFB1 and AFM1. Differences (P < 0.01) were found between AFB1 hepatic levels of group 0-AF (mean +/- SD: 4.13 +/- 1.95 ppb) and group MOS-AF (mean +/- SD: 2.21 +/- 1.37 ppb). The data demonstrated the ability of MOS to adsorb and degrade AFB1, reducing gastrointestinal absorption of AFB1 and its levels in tissues.

Soil physical changes and plant availability of Zn and Pb in a treatability test of phytostabilization

A treatability test of phytostabilization was carried out on two soils sampled downstream a mining Italian area with Lolium italicum and Festuca arundinacea. Beside chemical content of Pb and Zn in aerial parts and in roots, also some physical parameters were determined at the end of the growth cycle of plants. Particle size distribution was analysed with a laser granulometer while cracking patterns and porosity were determined by means of image analysis. Compost, used at two rates (10%, and 30% v/v) in order to improve soil physical characteristics, always raised biomass with similar effects for both doses. The concentration of Pb and Zn in aerial parts and in roots of L. italicum and F. arundinacea decreased more than five times in presence of compost. A general lack of clear effects of both plants on soil physical parameters was noticed. Formation of more water stable aggregates, a rise of the area occupied by cracks, and new porosity formed by elongated and irregular pores were found in soil samples treated with compost.

[Bacterial pneumonia in HIV-infected patients]

Patients and methods: This is a retrospective study performed on HIV-positive patients discharged from our Institution from January 1993 through December 1998 with a diagnosis of bacterial pneumonia. Cases of TB or atypical micobacterial infection were excluded from this analysis. Causative organisms were identified, when possible, by taking into account positive cultures from diverse sources (blood, sputum, pleural fluid and others). Results: In the 6-yr period we considered, 120 patients were identified. Among them, we were able to obtain clinical and imaging data on 98 cases. Focal infiltrates on chest X-ray studies were present in 87.7% of cases, 24.5% had a pleural effusion, 9.2% nodular lesions, 4.1% cavitary images and in 2 patients only hilar lymphadenopaties were noted. Causative agents resulted to be S. aureus (14 cases); P. aeruginosa (11); S. pneumoniae (6); R. equi (4); Enterobacter spp. and K. pneumoniae (3 cases each); E. coli, Peptostreptococcus spp and Enterococcus spp. (1 case each). No causative organism was isolated in 54 patients (55.1%) and the diagnosis was based on clinical and therapeutical grounds. Around half of cases (46.9%) responded well to therapy, while 11 (11.2%) died because of the lung infection. In 3 cases other opportunistic infections were the cause of death and 22 cases of relapse were recorded as well. Five patients resulted lost to follow-up. Conclusions: This retrospective study demonstrated a high prevalence of S. aureus lung infections along with the presence of otherwise rare causative organisms such as R. equi. Radiologic appearance of lung lesions did not differ substantially from the one of HIV negative patients. A relatively good response to antibiotic therapy was also noted.

Aflatoxin B1 and clinoptilolite in feed for laying hens: effects on egg quality, mycotoxin residues in livers, and hepatic mixed-function oxygenase activities

Ninety-six laying hens were allocated to four groups administered different diets (group 0-0 received a complete diet, group 0-AF received a diet supplemented with 2.5 ppm of aflatoxin B1 [AFB1], group 2-0 received a diet supplemented with 2% clinoptilolite [CPL], and group 2-AF received a diet supplemented with 2% CPL and 2.5 ppm of AFB1) for 4 weeks to evaluate the effect of AFBI and/or CPL on egg quality and the ability of CPL to interact with the oral administration of AFB1. The possible effects of AFB1 on cytochrome P450-dependent hepatic mixed-function oxygenase (MFO) activities were also evaluated. Mycotoxin reduced yolk weight, while CPL influenced albumen percentage relative to that of eggs laid by chickens in group 0-AF Eggs laid by chickens in groups 0-AF and 2-AF had stronger shells and weighed less than the eggs of other groups. The eggs of treated groups were lighter in color than those of the control group (P < 0.01), and the tendency to yellowness in eggs was increased by CPL, probably through the affinity of red pigments for adsorbents and a consequent prevalence of yellow tonality. Color parameters might be connected with AFB1's interference with lipid metabolism and pigment deposition. The livers of hens in groups 0-AF and 2-AF showed very low mycotoxin concentrations that were significantly different (P < 0.01). The highest levels observed were those in the livers of the hens receiving the diet supplemented with the mycotoxin alone. AFB1 did not exert any significant effects on the hepatic MFO activities examined.

Virological and immunological responses to a once-a-day antiretroviral regimen with didanosine, lamivudine and efavirenz

Current antiretroviral drugs cannot eradicate HIV infections, and persons living with HIV are often faced with very demanding daily therapeutic schedules that can induce poor adherence. More conveniently dosed and patient-friendly regimens are needed. We investigated, in this 48-week pilot study, a once-a-day highly active antiretroviral therapy regimen of didanosine, lamivudine and efavirenz. Seventy-five consecutive antiretroviral-naive subjects were enrolled. Over the 48-week period, plasma HIV-RNA levels declined sharply, with a median decrease at the end of the observation time >3.4 log copies/ml. The proportion of patients achieving a plasma HIV-RNA level below the limit of detection (50 copies/ml) was 77% (intention to treat analysis) at the end of the study period. The mean CD4 cell count increased steadily over time from 251 to 459 cells/microl. Antiviral efficacy was similar in patients with a baseline HIV-RNA level above or below 100,000 copies/ml. However, patients with a baseline CD4 cell count <200 cells/microl showed a significantly worse virological response than that observed in patients with higher baseline CD4 counts. Overall 15 patients interrupted therapy. In four cases treatment interruption was due to lack of treatment response; three additional patients were lost to follow-up or withdrew informed consent. Eight patients stopped therapy because of adverse events. The once-daily combination of didanosine, lamivudine and efavirenz resulted in sustained viral suppression and was well-accepted by patients. This regimen may offer advantages in selected difficult-to-treat populations, allows directly observed therapy and can be a safe and effective alternative in antiretroviral-naive patients. These encouraging pilot results need to be confirmed in a comparative clinical trial.

Myositis ossificans traumatica of the temporal muscle: a case report

Myositis ossificans traumatica (MOT) is a pathological condition characterized by extraskeletal formation of bony tissue, induced by violent or repeated trauma. Reports of this pathology occurring in the region of the head and neck are rare, and even more so in the muscles of mastication. We present the case of patient with MOT of the temporal muscle, the etiology of which seems to be related to traumatic manipulations during dental treatment. A review of the literature is presented and the surgical approach, which resolved this case is discussed.

Carbon emissions. The economic benefits of the Kyoto Protocol

The third Conference of the Parties in Kyoto set the target of reducing greenhouse-gas emissions by an average of 5.3% with respect to 1990 values by 2008-2012. One of the main objections to the protocol's ratification is that compliance would pose an unbearable economic burden on the countries involved. But we show here that this is not the case if costs apart from the direct costs of energy production are also considered. Costs are also incurred in rectifying damage to human health, material goods, agriculture and the environment related to greenhouse-gas emissions.

[Organizational appropriateness of recoveries: results of the evaluation of recoveries by AEP/PRUO at the Careggi Hospital in Florence in 1995-1998]

The organizational appropriateness of hospital stays is an expression of a hospital's efficiency and aim of the management control. The AEP (American Version)/PRUO (Italian Version) protocol is specific for measuring the organizational appropriateness of hospital stays. The aim of this study is the comparative analysis of the organizational appropriateness of hospital stays in Careggi Hospital of Florence and in all hospital Departments in 1995 and 1998. In 1998 the AEP/PRUO protocol was applied to 2148 samples of hospital stays out of 38,968 eligible hospitalizations, and in 1995 a sample of 1989 hospital stays out of 35,108. In 1998 2,148 admissions and 15,338 days of hospitalization were tested. In 1995, 1989 admission days and 12,264 days of hospitalization were tested, 63 departments were studied. In 1995 the first edition of the protocol was applied, in 1998 the second. A sample of 218 of the 1998 hospital stays was tested with both editions to evaluate the impact of differences. In 1998, with the second edition of the protocol, the inappropriateness rate of admission days and hospitalization days and the rate of in-patients inappropriate hospital stays was respectively 38.0%, 43.8% and 18.5%. Compared with 1995 results, the rates increased +6.2%, 6% and +7.5% respectively. Instead, with the first edition of the protocol, the rates were 29.7%, 37.6% and 10.7% and, compared with 1995, they were reduced -2.1%, -0.6% and -0.3%. The longitudinal multilevel analysis has allowed the evaluation of the performance of each department.

Integrated treatment in locally advanced carcinoma of the oropharynx

BACKGROUND AND OBJECTIVES

Oropharyngeal carcinoma tends to be aggressive and deeply infiltrative of nearby sites, with an high incidence of lymph node metastases. The last treatment decision generally depends on the stage of the lesion and the patient's general status. Oropharyngeal tumor is generally treated by integrated treatments.

METHODS

We retrospectively studied 115 patients with locally advanced oropharyngeal tumors treated in our institution with combined therapies compare the results in two different groups of patients (surgery plus radiotherapy and chemotherapy plus radiotherapy).

RESULTS

The 3-year overall survival rate in patients who underwent surgery plus radiotherapy was 82% and in those who underwent chemotherapy plus radiotherapy was 49%.

CONCLUSION

The results suggest that surgery followed by radiotherapy seems to be the best treatment in the case of locally advanced oropharyngeal tumor.

Road traffic accidents with vehicular entrapment: incidence of major injuries and need for advanced life support

Road traffic accidents (RTAs) with entrapment are perceived as a challenge to emergency systems because of the severity of the ensuing traumas and the inherent complexity of the rescue procedures. To clarify these two aspects this prospective cohort study enrolling 244 entrapped trauma patients was conducted by a Regional Medical Helicopter Service. Forty-six victims (18.9%) were found dead, 101 (51%) of the 198 patients who reached the hospital alive had an injury severity score (ISS) > or = 16. The use of seat belts was associated with lower trauma severity. Out of the 101 severely traumatized patients (ISS > or = 16), 46 (42.6%) were intubated at road side, 12 required decompression of a tension pneumothorax on the scene and in 15 cases a pneumothorax was drained during the early intrahospital phase. Thirty-six (34.7%) patients had the first systolic blood pressure (SBP) < or = 90 mmHg and were then aggressively infused: in 75% of these cases, the SBP on arrival at the emergency department increased. The first SBP was significantly correlated with mortality. There was no correlation of extrication time, total rescue time and mortality. Fourteen patients (13.9%) died during hospitalization. These data demonstrate that a high percentage of entrapped patients require advanced life support (ALS), including on scene intubation and chest decompression. Aggressive field resuscitation and immediate transport to a level 1 trauma centre is associated with a mortality lower than that predicted by TRISS in spite of the prolonged prehospital time.

Successful treatment of spleen tuberculosis in a patient with human immunodeficiency virus infection

Tuberculosis in human immunodeficiency virus (HIV)-infected patients may act as a cofactor that accelerates the clinical course of HIV infection, and, indeed, HIV-infected patients with tuberculosis have a reduced survival rate compared to those without tuberculosis. Diagnosis of tuberculosis in HIV-positive patients can be difficult because of nonspecific symptoms and the time required for the identification of mycobacteria by means of culture techniques. Recently, antiretroviral combination therapies have improved the outcome of several acquired immune deficiency syndrome (AIDS)-associated conditions. Unfortunately, the use of antiretroviral therapy for patients coinfected with HIV and Mycobacterium tuberculosis is still to be fully evaluated. The complexity of side-effects due to antituberculosis medication and drug interaction represent important issues and combining an effective anti-HIV treatment with antituberculosis therapy is still a clinical challenge. We discuss here a case of spleen tuberculosis in a human immunodeficiency virus-positive patient who had a successful response after a diagnostic splenectomy and medical treatment that included classical antituberculosis treatment associated with antiretroviral therapy without protease inhibitors.

Postoperative blood salvage in hip and knee arthroplasty. A prospective study on cost effectiveness in 161 patients

We conducted a prospective controlled study on 161 patients who underwent primary or revision total hip or knee arthroplasty to assess the efficacy and limitations of postoperative blood salvage. The actual quantity of blood salvaged after washing, the theoretical increase in hemoglobin concentration caused by its reinfusion and the cost of this procedure were studied. The mean amount of packed red cells after washing was 117 g. The average increase in hemoglobin concentration, which theoretically would have been achieved by retransfusion, was 0.47 g/dL. One third of the devices used were discarded as not effective enough and, in order to obtain an increase of 1 g/dL in the hemoglobin concentration, an average of 3.4 postoperative Solcotrans Plus Orthopaedic devices were used. To obtain the same increase in hemoglobin concentration as that given by an allogeneic blood transfusion, the overall cost of materials alone was more than five times the price of a single blood unit transfusion.

Headache in patients with neurofibromatosis type 1

A study of headache in a homogeneously ascertained population of 181 subjects suffering from neurofibromatosis type 1 is described. All subjects underwent a diagnostic protocol including imaging studies (for subjects over 5 years old up until 1992). Headache data were collected by means of a questionnaire. Headache was present in 55 of 181 subjects (25 males). Overall headache frequency was 30%, which is not significantly different from the frequency of headache reported in the general population. Headache was primary in 52 cases (5 migraine and 47 tension-type) and secondary to obstructive hydrocephalus with brain tumor-induced intracranial hypertension in 3 with a tension-type pattern. It was concluded that headache is not a specific feature of neurofibromatosis type 1, it is not significantly related to central nervous system abnormalities, and in itself, it is not an indication for neuroradiological examination.

Critical analysis of intramedullary nailing by the Ender method in the treatment of intertrochanteric fractures

A retrospective study was carried out to evaluate the results of intramedullary fixation by Ender nailing in the treatment of intertrochanteric fractures. During the period 1980-1989, 85 patients were treated with this method at the Orthopedic Department of the Università Cattolica in Rome. Evaluation of the cases took into account the patient's characteristics (age, sex, weight, height, obesity, previous or concomitant illness, level of autonomy, mental condition, type of fracture, time elapsed before operation and laboratory tests), details of the operation (length, accuracy of reduction and mechanical fixation stability, post-operative hospitalization period and general and local complications) and follow-up evaluation (X-ray examination, functional examination and evaluation of the results). Analysis of the observations showed that, although it induced less surgical trauma, internal fixation by the Ender method did not ensure a stable reduction, particularly with highly comminuted and basicervical fractures. As a result, the elective indication for this method should be restricted to stable intertrochanteric fractures, particularly in patients with a generally poor condition.

Survival after trochanteric fracture. Biological factors analyzed in 270 patients

Factors that influence mortality were analyzed in 270 patients operated on for trochanteric hip fracture. Survival was closely related to age and medical condition at the time of injury; methods of treatment had little influence on survival.

[Evaluation of fracture healing with the computerized analysis of radiographic images]

The radiographic evaluation of fracture healing in the long bones utilizes subjective and hardly analytic standards. Therefore, to solve this problem, the authors suggest using a computerized image processing system which increases radiographic informative content and allows an objective evaluation of fracture healing. We analyzed the radiographs of 15 patients suffering from femoral fracture and treated by means of Küntscher nailing. We processed the radiographs taken both before and 1, 2, 4, and 6 months after surgical treatment. It was thus possible to select the regions of interest, to graph brightness levels and to measure both distances and areas. Computerized image processing provides an objective and quantitative analysis of radiographs and allows an increase in informative content. It also allows the comparison of pre- and postoperative radiographs with those taken at different times. Our results may confirm the utility of computerized image analysis of radiographs to evaluate bone remodelling during fracture healing.

Screening for anti-human T-lymphotropic virus antibody in blood donors and polytransfused patients in Apulia (Italy)

A stringent procedure for the diagnosis of human T-lymphotropic virus (HTLV) infection was applied to 1,732 volunteer blood donors, 401 patients with various hematological disorders and 78 individuals at high risk for HIV infection. It consisted of a viral lysate-based screening assay (Abbott Laboratories, North Chicago, Ill., USA), and two confirmatory assays (Western blot and radioimmunoprecipitation assay). A confirmed positive sample had to react with at least two different HTLV gene products. Evidence of HTLV infection was not found in either blood donors or patients with hematological disorders. In fact, HTLV infection was only observed in 10 intravenous drug abusers or their sexual partners. Contrary to previous reports that claimed HTLV seroprevalences of between 0.3 and 8% in blood donors from Apulia (Italy), our data suggest that infection with this virus is principally restricted to intravenous drug abusers.