Detectability of early brain meningitis with magnetic resonance imaging

RATIONALE AND OBJECTIVES

The ability of high-field (1.5 T) magnetic resonance imaging (MRI) to detect early brain meningitis was evaluated in a canine model. Contrast dose, timing postinjection, and imaging technique (specifically the use of magnetization transfer) were assessed.

METHODS

Imaging of five canines was performed at 1.5 T 24 hours after injection of Cowans staphylococcus into the cisterna magna. Two control animals also were imaged using the same protocol, with one animal receiving a cisternal injection of nutrient broth only and the other no injection. Contrast doses of 0.1, 0.3, and 0.8 mmol/kg gadoteridol (Gd HP-DO3A or Pro-Hance) were compared. Scans were performed at 2, 12, and 22 minutes after an initial injection of 0.1 mmol/kg. At each time point, paired T1-weighted scans with and without magnetization transfer (MT) were acquired. Thirty minutes after the initial injection of contrast, a supplemental dose of 0.2 mmol/kg was given (for a cumulative dose of 0.3 mmol/kg). Scans were then repeated at 2, 12, and 22 minutes after this dose was administered. A second supplemental contrast injection of 0.5 mmol/kg (for a cumulative dose of 0.8 mmol/kg) was given at 70 minutes, and immediate postinjection scans with and without MT were acquired.

RESULTS

In the animals receiving a cisternal injection of bacteria, the degree of meningeal enhancement was greatest at 0.8 mmol/kg, intermediate at 0.3 mmol/kg, and least at 0.1 mmol/kg. These conclusions were constant whether imaging was performed with or without MT. Scans in control studies did not demonstrate abnormal meningeal enhancement. High-contrast dose, MT, and acquisition of immediate postcontrast scans all resulted in statistically significant improvement. On masked film review, abnormal meningeal enhancement was noted in only 2 of 5 experimental dogs at a dose of 0.1 mmol/kg (regardless of the use of MT) compared with all animals at a dose of 0.3 mmol/kg. In 18 of 37 dogs (paired scans with and without MT), when abnormal enhancement was noted, the use of MT improved the visualization of abnormal meningeal enhancement.

CONCLUSIONS

In early brain meningitis, high-contrast dose (0.3 mmol/kg), MT, and scanning immediately after injection improve detection of abnormal meningeal enhancement, thus facilitating the diagnosis of meningitis. Of these factors, contrast dose is the most important.

Comparison of gadolinium Cy2DOTA, a new hepatobiliary agent, and gadolinium HP-DO3A, an extracellular agent, in healthy liver and metastatic disease

RATIONALE AND OBJECTIVES

A new gadolinium (Gd) chelate with preferential hepatobiliary uptake, Gd Cy2DOTA, was compared in two animal species with Gd HP-DO3A (gadoteridol), a clinically approved contrast agent with extracellular distribution. Liver enhancement was evaluated for these two contrast agents using magnetic resonance imaging, whereas an experimental model of metastatic disease was used to evaluate the agents' efficacy for liver-lesion delineation.

METHODS

The two agents were compared in four healthy Rhesus monkeys (eight studies) and five New Zealand White rabbits with implanted VX-2 liver tumors (ten studies). The contrast dose was 0.1 mmol/kg, with the agents given in random order and at least 72 hours between contrast injections. Breathhold T1-weighted spin echo scans were obtained at 1.5 tesla (T) before and after contrast was administered. Postcontrast scans were obtained 1 to 90 minutes after injection in the monkeys and 1 to 240 minutes after injection in the rabbits.

RESULTS

Prolonged hepatic enhancement, superior in degree to that with Gd HP-DO3A, was noted in both monkeys and rabbits after injection of Gd Cy2DOTA. Two minutes after contrast, liver SI was 1.94 +/- 0.05 with Gd Cy2DOTA compared with 1.51 +/- 0.05 with Gd HP-DO3A in monkeys. Sixty minutes after contrast, liver SI was 1.60 +/- 0.09 compared with 1.20 +/- 0.02. The difference between agents was significant at all times from 2 to 60 minutes after contrast injection (P < 0.01). Excretion of contrast into the gall bladder was observed in both animal species with Gd Cy2DOTA but not with Gd HP-DO3A. The maximum improvement in lesion conspicuity (rabbit) occurred 45 minutes after injection of Gd Cy2DOTA and 5 minutes after injection of Gd HP-DO3A. Sixty minutes after injection, liver-lesion contrast was 246 +/- 61 with Gd Cy2DOTA and 106 +/- 28 with Gd HP-DO3A, with a significant difference (P < 0.02).

CONCLUSIONS

Gd Cy2DOTA provides greater enhancement of the liver parenchyma on immediate and delayed magnetic resonance scans than does Gd HP-DO3A. On delayed scans, Gd Cy2DOTA provides superior delineation of metastatic liver lesions.

Magnetic resonance imaging of an experimental model of intracranial metastatic disease. A study of lesion detectability

RATIONALE AND OBJECTIVES

The detectability of brain metastases was evaluated in a rabbit model, with attention to magnetic resonance contrast dose and timing of image acquisition after injection of contrast medium.

METHODS

Five New Zealand white rabbits were studied at 1.5 T 6 to 7 days and 11 to 12 days after surgical implantation of an adenocarcinoma tumor nidus. T1- and T2-weighted spin-echo images (0.9 x 0.9 x 2 mm3 voxel size) were obtained before administration of contrast medium. T1-weighted images were repeated 5, 15, and 30 minutes after intravenous injection of 0.1 mmol/kg gadoteridol. At 40 minutes, a supplemental dose of 0.2 mmol/kg (0.3 mmol/kg cumulative dose) was administered, with T1-weighted images repeated at 5, 15, and 30 minutes after the second injection.

RESULTS

Six to 7 days after tumor implantation, lesion enhancement (percent change, with normalization to baseline and equilibrium values) was 42 +/- 9% at 5 minutes, 48 +/- 9% at 15 minutes, and 42 +/- 10% at 30 minutes after administration of 0.1 mmol/kg gadoteridol. After administration of 0.3 mmol/kg gadoteridol, lesion enhancement was 111 +/- 13% at 5 minutes, 116 +/- 8% at 15 minutes, and 100% at 30 minutes. On film review, 2 of 5 lesions were not detectable at 6 to 7 days after tumor implantation with 0.1 mmol/kg gadoteridol. Administration of 0.3 mmol/kg gadoteridol provided for lesion identification in each instance. Eleven to 12 days after tumor implantation, one lesion was not detectable with 0.1 mmol/kg gadoteridol. Administration of 0.3 mmol/kg gadoteridol again provided for lesion identification in all cases. Mean lesion enhancement increased from 39 +/- 15% to 104 +/- 10%.

CONCLUSIONS

The administration of 0.3 mmol/kg gadoteridol (high dose) compared with 0.1 mmol/kg gadoteridol (conventional dose) improves metastatic lesion detectability in the brain. The lesions identified only at high dose were confirmed by histopathology. Smaller lesions were not detected at a dose of 0.1 mmol/kg.

HIV-related deaths from selected infectious diseases among persons without AIDS in New Jersey

This study sought to quantify HIV-related deaths among persons not classified as having AIDS, in an area where AIDS incidence among injecting drug users (IDUs) is high. Death certificates of persons who were aged 25-44 years at death, died in 1987 in two New Jersey counties, and had certain infectious conditions were compared with names in the AIDS Registry. Hospital and/or Medical Examiner records were reviewed for nonmatching cases. Cases were considered as confirmed HIV infection if there was laboratory evidence of such infection and as suggestive HIV infection if the decedent had oral thrush or a combination of certain other clinical findings were present. Of 412 deaths meeting the above criteria, 165 (40.0%) were in the AIDS Registry. We investigated 205 of the remainder; of these, 7.3% were found to have AIDS, 21.5% had confirmed HIV infection without AIDS, and 15.1% had suggestive HIV infection. This increased the HIV-related mortality in excess of deaths due to AIDS in this age group by 9.2% for confirmed HIV infections and 15.6% for both confirmed and suggestive HIV infections, with deaths among IDUs increasing 12.3% for confirmed HIV infections and 18.9% for both confirmed and suggestive HIV infections. Thus, in addition to AIDS indicator diseases, a variety of other infectious conditions can lead to death in HIV-infected persons, particularly in IDUs; however, the extent of such deaths may be less than previously described.

Respiratory burst activity associated with phagocytosis of Ehrlichia risticii by mouse peritoneal macrophages

Peritoneal macrophages from two strains of mice, BALB/c and C3H/HeN, were analysed by flow cytometry for a respiratory burst associated with the phagocytosis of Ehrlichia risticii. Resident murine peritoneal macrophages failed to respond with a respiratory burst after phagocytosing E risticii. In contrast, mice previously infected with E risticii yielded peritoneal macrophages that did generate a respiratory burst on phagocytosing ehrlichiae.

Humoral antibody and lymphocyte blastogenesis responses in BALB/c, C3H/HeJ and AKR/N mice following Ehrlichia risticii infection

Three strains of mice, two susceptible to Ehrlichia risticii induced disease (BALB/c and C3H/HeJ) and one resistant (AKR/N), were evaluated for the development of humoral and cell mediated immune responses following infection with E risticii. The production of serum antibody was determined by indirect fluorescent antibody testing of sera from mice of each strain challenged with one of three different dose levels of E risticii. Antibody was assayed on days 7, 9, 12, 15 and 20 after inoculation. Cell mediated immune responses were evaluated by measuring the blastogenesis response of spleen cells from E risticii infected mice 28 days after inoculation. All three strains of mice at the high challenge level responded with the production of antibody by day 9 after inoculation. Overall, the antibody response occurred earlier and was of greater magnitude in the susceptible BALB/c and C3H/HeJ strains. A marked blastogenesis response occurred in splenocytes from E risticii infected mice of all three strains upon re-exposure to ehrlichial antigen. The findings of this study indicate that susceptibility to E risticii induced disease was not the result of deficient or delayed humoral immune responses and that E risticii infection induced the development of strong cell mediated immunity.

Variation in susceptibility of ten mouse strains to infection with a strain of Ehrlichia risticii

Eight inbred strains of mice (A/J, AKR/NCrlBR, BALB/cAnNHsd, C3H/HeJ, C3H/HeNHsd, C57BL/6J, C57BL/10SnJ and CBA/J) and two outbred strains (CF1 and ICR) were inoculated with a strain of Ehrlichia risticii and their relative susceptibility to disease was determined. The strains varied widely in susceptibility, some showing profound illness, with illness being barely detectable in others. Severity of illness was uniform within strains. This study confirmed that the A/J and BALB/cAnNHsd strains were very susceptible to illness, but the C3H/HeJ, CBA/J and the CF1 strains were slightly less susceptible. The C57BL/6J, C57BL/10SnJ, C3H/HeNHsd, AKR/NCrlBR and ICR strains were resistant.

Retention and attempted mechanical transmission of Ehrlichia risticii by Stomoxys calcitrans

The ability of adult Stomoxys calcitrans (L.) (Diptera: Muscidae) to retain viable Ehrlichia risticii (Rickettsiaceae), the aetiologic agent of Potomac horse fever (PHF), and mechanically transmit the pathogen from citrated bovine blood artificially infected with E. risticii to susceptible mice was studied. Viable E. risticii were found in the digestive tract of S. calcitrans 3 h after the flies had engorged to repletion on infected blood; however, no E. risticii were detected in flies > or = 2 days after feeding. Subsequently, groups of S. calcitrans were fed for 20 s on infected blood, then fed to repletion on mice 30, 60, 130, 180 or 220 min after having feeding interrupted. Mice displayed no clinical signs of PHF and did not produce anti-E. risticii antibodies when assayed 30 days after S. calcitrans had fed. Although S. calcitrans were able to harbour viable E. risticii for at least 3 h, transmission of the disease agent to susceptible mice during interrupted feeding was not demonstrated under these experimental conditions.

The incidence and management of catheter occlusion in patients on home parenteral nutrition

For patients on Home parenteral nutrition (HPN), catheter-related problems are the major source of morbidity and occlusion of the central venous catheter is one of these. We have managed 17 episodes of catheter occlusion in 10 patients on HPN. The median time from insertion to occlusive episode was 23 months. 10 catheters (59%) were saved by the used of thrombolytics (one by thrombolytics and ethanol) and 7 were replaced. The recent incidence of catheter occlusion in this cohort was one episode per 150 patient-months of HPN (0.08 episodes per year). Patients with Crohns disease appear to be at greater risk of developing catheter occlusion (p = <0.05).

Characterization of equine oviductal proteins synthesized and released at estrus and at day 4 after ovulation in bred and nonbred mares

Proteins synthesized and released in vitro by oviducts collected from horse mares during estrus and at day 4 after ovulation for bred and nonbred mares were examined by two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (2-D SDS PAGE) and fluorography. Ampullary and isthmic regions both produced a wide array of nondialyzable proteins in culture. Major proteins or groups of proteins identified according to relative molecular weight (kDa) and apparent isoelectric point (pI) were at 100 kDa, pI 8; 100-200 kDa, pI 6; 150 kDa, pI 4.5; 60-100 kDa, pI 4; and an array of polypeptides at 21-22 kDa, pI 5-6. Oviductal secretory activity, measured by incorporation of radiolabeled amino acids into nondialyzable macromolecules released into incubation medium, was greater (P < .01) for the ampullary than the isthmic oviductal region. No consistent differences were observed in fluorograms between estrus vs. day 4 after ovulation, ampulla vs. isthmus, ipsilateral vs. contralateral to the corpus luteum or largest follicle, oviducts from bred vs. nonbred mares, or mare ages. Dialyzed medium from ampullary and isthmic regions of oviducts was subjected to 1-D or 2-D SDS PAGE followed by western blotting utilizing an antiserum directed against human retinol binding protein (RBP). The family of 21-22 kDA polypeptides was identified as immunoreactive RBP.

Endoscopic transanal resection in the management of patients with sessile rectal adenomas, anastomotic stricture and rectal cancer

Forty patients underwent 61 endoscopic transanal resections using a urological resectoscope. Preoperative diagnoses were adenoma in 28 patients, carcinoma in seven and benign anastomotic stricture in five. Four patients with adenomas were found to have frank carcinoma. Ablation of 22 of 23 adenomas was achieved, 11 with a single transanal resection. Open operation was required for one patient. Locally advanced rectal malignancy was palliated in five of seven patients. All those with benign anastomotic stricture were cured by a single resection. The median operating time was 25 min, with 11 procedures exceeding 30 min. There were complications in seven cases (six bleeding, one septicaemia). The median hospital stay for the procedure alone was 3.5 days. There were no deaths within 30 days of operation. Endoscopic transanal resection is minimally invasive, quick, safe and effective. Histological surveillance is a major advantage and appears reliable. Low complication rates can be achieved by opting for several 'easy' resections and by restricting use of the procedure to lesions within 15 cm of the anal verge.

Adolescent substance use during pregnancy

Substance use during pregnancy may be a key mediator of the association between adolescent childbearing and poor newborn outcome. Substance use during pregnancy was evaluated for 50 teens who were consecutive patients at an inner-city university clinic. Although teens reported typical lifetime rates of substance use, self-reports and two urine assays indicated minimal substance use throughout pregnancy. Findings suggest that the adolescents exercised judicious decision making in light of the known health risks of substance use during pregnancy.

In vitro killing of Ehrlichia risticii by activated and immune mouse peritoneal macrophages

Normal resident murine peritoneal macrophages inoculated in vitro with Ehrlichia risticii readily phagocytized the organism but were unable to suppress ehrlichial replication as determined by indirect fluorescent-antibody staining of the inoculated cells. In contrast, macrophages from Corynebacterium parvum-inoculated and E. risticii-recovered mice rapidly eliminated the ehrlichiae. Macrophages from E. risticii-recovered mice were as effective as the C. parvum-activated cells in phagocytizing and eliminating the organism. Opsonization of E. risticii with homologous antiserum prior to inoculation of macrophage cultures resulted in enhancement of phagocytosis and greater suppression of E. risticii replication in all macrophage groups. These findings indicate that the pathogenesis of E. risticii infection centers on the ability of the organism to enter and replicate within the macrophage with avoidance of macrophage antimicrobial effects. An immune response results in macrophage activation with enhancement of the macrophage's ability to eliminate E. risticii. Opsonization of E. risticii with anti-E. risticii serum renders E. risticii more susceptible to macrophage destruction.

Equine protozoal myelitis in Panamanian horses and isolation of Sarcocystis neurona

Schizonts of Sarcocystis neurona were identified microscopically in hematoxylin-eosin-stained spinal cord sections from 2 native Panamanian horses that exhibited clinical signs of equine protozoal myelitis (EPM). Spinal cord homogenate from a third Panamanian horse with EPM was inoculated onto monolayers of cultured bovine monocytes (M617). Intracytoplasmic schizonts containing merozoites arranged in rosette forms surrounding a central residual body first were observed 13 wk postinoculation. Parasites divided by endopolygeny and lacked rhoptries. Schizonts from each horse reacted with Sarcocystis cruzi antiserum in an immunohistochemical test.

The effect of a school entry law on mumps activity in a school district

Sixty-three cases of clinical mumps occurring in a New Jersey school district presented an opportunity to determine compliance with the state's 1978 mumps "new entrants" school immunization law, investigate the effect of the law on the pattern of the outbreak, estimate the efficacy of mumps vaccine, and quantitate the economic impact of the outbreak. Only students in kindergarten (K) through grade 5 would have been affected by the immunization law. Students in the sixth grade were nearly seven times more likely to develop mumps than students in grades K through 5. The observed differences between the sixth graders and those in grades K through 5 most likely reflect the fact that sixth graders were not covered by the school law. Vaccine efficacy was estimated to be 91% (95% confidence interval = 77% to 93%). The total direct cost of the outbreak was $10,937 (clinic costs plus total cost to households). This outbreak demonstrates the significant impact of appropriate school vaccination laws on limiting the morbidity and economic and social costs of mumps.

Transmission of measles in medical settings. 1980 through 1984

For the five-year period 1980 through 1984, a total of 241 persons with measles in 30 states were identified as probably having acquired their infection in a medical facility. The proportion of all measles cases acquired in medical settings increased from 0.7% for 1980 through 1982 to 2.9% for 1983 and 1984. Seventy-six percent of cases were found in patients or visitors, and 24% in personnel at the medical facility where transmission occurred. The highest proportion of cases occurred in children less than 5 years of age (54.3%), followed by persons 25 to 29 years of age (14.7%). Of spread (50.0%) and patient-to-staff spread (36.7%) were most common. Medical personnel rarely transmitted disease to others. More attention needs to be given to methods of preventing spread of measles in medical facilities, such as isolation precautions, postexposure prohylaxis of potential contacts (vaccination or immune globulin), and ensuring that medical personnel are immune to measles.

Fetal risk associated with rubella vaccine: implications for vaccination of susceptible women

The Centers for Disease Control has maintained a register of women who received rubella vaccine within three months before or three months after conception to follow prospectively the outcome of pregnancy and to quantitate the risks to the fetus from the vaccine virus. The data indicate that rubella vaccine can cross the placenta and rarely can infect the fetus. However, no abnormalities consistent with congenital rubella syndrome have been noted in 144 infants whose susceptible mothers received the RA 27/3 rubella vaccine, the only vaccine available in the United States since 1979. Although the observed risk of defects consistent with congenital rubella syndrome is zero, there is a statistical theoretic risk of a congenital rubella syndrome-like defect; the maximum theoretic risk is 2.6%. These findings indicate that vaccination of nonpregnant postpubertal women who lack either serologic proof of immunity or a written record of vaccination on or after the first birthday can be done safely and effectively. Whereas congenital rubella infection will disappear from the United States as vaccinated children enter the childbearing years, if these practices are followed elimination of congenital rubella infection will be hastened.

Fetal risk associated with rubella vaccine: an update

One hundred nineteen women susceptible to rubella received RA27/3 vaccine, 94 received either Cendehill or HPV-77 vaccine, and one received a vaccine of unknown strain in the three months before or after their estimated date of conception. They gave birth to 216 living infants free of abnormalities compatible with the congenital rubella syndrome (CRS). The maximum theoretical risk for CRS for these infants was 1.7%. Four of these infants born to susceptible women had laboratory evidence of subclinical infection (three after receiving Cendehill or HPV-77 vaccines and one after receiving RA27/3 vaccine) but were normal at birth and at subsequent follow-up examinations. Rubella virus was isolated from the products of conception for only 3% (1 of 32) of cases involving susceptible women who received RA27/3 vaccine; the reported rate of virus isolation for Cendehill and HPV-77 vaccine is 20%. The available data indicate that if vaccination occurs within three months of conception, the risk is negligible. However, since the actual risk may not be zero, women known to be pregnant should not be vaccinated, and conception should be avoided for three months after vaccination.