An observational study on the safety of COVID-19 vaccination in patients with myasthenia gravis

OBJECTIVE

There is concern that the coronavirus disease (COVID-19) vaccine may trigger or worsen autoimmune diseases. The objective of this study was to determine the impacts of COVID-19 vaccination on symptom severity in patients with myasthenia gravis (MG).

METHODS

A total of 106 enrolled patients with MG who were vaccinated against COVID-19 were followed up, and a questionnaire was used to document in detail the exacerbation of muscle weakness after vaccination and all other uncomfortable reactions after vaccination. Demographic, clinical characteristics, medication, and vaccination data were collected by follow-up interview. The main observation outcome was whether the MG symptoms of patients were exacerbated. The definition of exacerbation is according to the subjective feeling of the patient or a 2-point increase in daily life myasthenia gravis activity score relative to before vaccination, within 30 days after vaccination.

RESULTS

Of 106 enrolled patients [median age (SD) 41.0 years, 38 (35.8%) men, 53 (50.0%) with generalized MG, 74 (69.8%) positive for acetylcholine receptor antibody, and 21 (19.8%) with accompanying thymoma], muscle weakness symptoms were stable in 102 (96.2%) patients before vaccine inoculation. Muscle weakness worsened in 10 (9.4%) people after vaccination, of which 8 patients reported slight symptom worsening that resolved quickly (within a few days). Two (1.9%) of patients showed serious symptom aggravation that required hospitalization.

CONCLUSION

Our results suggest that inactivated virus vaccines against COVID-19 may be safe for patients with MG whose condition is stable. Patients with generalized MG may be more likely to develop increased muscle weakness after vaccination.

[Analysis of clinical characteristics and related genetic variation of juvenile myasthenia gravis]

Objective: To analyze the clinical characteristics and related genetic variation of juvenile myasthenia gravis (MG) patients. Methods: We collected the clinical data of adolescent MG patients who were treated in the Department of Neurology of the First Affiliated Hospital of Sun Yat-sen University from June 2019 to May 2020. After obtaining the patient's informed consent, the blood samples were collected. The Whole Exome Sequencing (WES) was performed on peripheral blood samples. And use biological information software and SPSS 22.0 for data processing and result analysis. Results: According to the inclusion and exclusion criteria, 54 patients with juvenile MG were included, 28 males and 26 females. And the average age of onset was (3.79±0.89) years. Among the enrolled patients, there were 52 (96.3%) patients with ocular MG, the MG-ADL scores of 54 patients were (3.44±0.44) points, and the titer of AChR antibody was (5.88±2.45) nmol/L. Two patients had thymic hyperplasia, and 5 patients had a family history of MG.A total of 169 variant genes were found in 54 patients, of which TTN gene variants had the largest number, with a total of 17 variants (31.5%). In the TTN gene variant group, 7(41.2%) patients had eye fixation symptoms, and 4 (10.8%) patients in the non-mutation group had eye fixation symptoms. And The difference between the two groups was statistically significant (P=0.016). In addition, the synaptic nucleus envelope protein-1 (SYNE1) and the ryanodine receptor-1 (RYR1) gene variations were also found in 7 cases (13.2%), and no clear relationship between these gene variations and clinical manifestations of MG was found. Conclusions: The incidence of juvenile MG was preschoolers with no gender difference, and ocular MG was more common. The proportion of TTN gene variation in adolescent MG was higher, suggesting that this gene may be a potential therapeutic target for juvenile MG patients.

[Clinical characteristics and outcomes of myasthenia gravis patients with double positive antibodies against acetylcholine receptor and muscle-specific tyrosine kinase]

Objective: To investigate the clinical manifestations, treatment characteristics and outcomes of myasthenia gravis (MG) dually positive for anti-acetylcholine receptor antibody (AChR-Ab) and anti-muscle-specific tyrosine kinase antibody (MuSK-Ab). Method: MG patients hospitalized in the First Affiliated Hospital of Sun Yat-sen University from August 2017 to November 2020 were retrospectively collected. Thirty-four MuSK-Ab positive MG (MuSK-MG) patients, 11 double-antibodies positive MG (DP-MG) patients, and 80 AChR-Ab positive MG (AChR-MG) patients were included and allocated to three different groups. The clinical data of patients in the three groups were collected, and the differences of demographic characteristics, clinical manifestations and treatment outcomes between DP-MG patients and AChR-MG and MuSK-MG patients were analyzed. Result: The proportion of female and male patients in DP-MG group was 7/11 and 4/11 respectively, and the onset age of DP-MG was (41±27) years.The difference in gender distribution between DP-MG and AChR-MG groups was statistically significant (P<0.05). The proportion of extraocular muscle involvement in the DP-MG and MuSK-MG groups (8/11 and 52.9%) was lower than that in the AChR-MG group (83.8%), and the difference was statistically significant (P<0.05). The incidence of myasthenia crisis in DP-MG and MuSK-MG groups (54.5% and 61.8%) were higher than that in AChR-MG group (20.0%), with astatistically significant difference(P<0.05). The positive rate of neostigmine test in DP-MG and MuSK-MG groups(8/11 and 74.2%) were lower than that of AChR-MG group (96.8%), and the positive rate of low frequency repetitive nerve stimulation (RNS) in DP-MG group (5/10) was lower than that in AChR-MG group (85.1%), with statistically significant differences (all P<0.05). MuSK-Ab titer was positively correlated with the course of disease (r=0.466, P<0.05), and antibody titer decreased after symptom improvement (P<0.05). The response of patients in DP-MG and MuSK-MG groups to cholinesterase inhibitors (2/11 and 9.1%) was worse than that in the AChR-MG group (66.3%), and the incidence of side effects in the two groups (5/11 and 39.4%) was higher than that in the AChR-MG group (15.0%), with statistically significant differences (all P<0.05). There were 4 DP-MG patients underwent thymectomy, and the pathological results detected two cases of thymoma and two cases of thymic hyperplasia. Subsequent follow-up showed that 5 (5/11) DP-MG patients achieved minimal manifestation status or better status. Conclusion: The gender distribution, age of onset, pharmacological characteristics and electrophysiological examination of DP-MG patients were similar to those of MuSK-MG patients, but the severity of DP-MG patients was between that of AChR-MG and MuSK-MG patients.

[Characteristics of electromyography in 111 patients with generalized myasthenia gravis: a retrospective study]

Objective: To retrospectively analyze the characteristics of the electromyography (EMG) study in generalized myasthenia gravis (gMG) patients. Methods: A total of 111 gMG patients were enrolled. Patients were divided into two groups: 36 severe patients discontinuing pyridostigmine bromide (PB) for 8 hours were included in 8 h group, and 75 g MG patients discontinuing PB for at least 18 hours were included in>18 h group. The clinical information and EMG study data were collected and analyzed. Results: There were statistically significant differences in the initial location of the myasthenia muscle (P=0.027), the affected muscle detected by the EMG (P=0.015) and quantitative myasthenia gravis (QMG) score (P<0.01) between the two groups. Comparisons in each group revealed that the highest positive rate of low-frequency repetitive nerve stimulation (RNS) of facial in 8 h group and>18 h group was 94.4% and 60.0%, respectively. Comparisons between the two groups showed that the positive rate of low-frequency RNS in 8 h group was significantly higher than that in>18 h group (94.4% vs 70.7%, χ(2)=8.115, P=0.004). In particular, the positive rate of RNS in facial nerves and the extent of the amplitude decrease under different electrical stimulations (1 Hz, 3 Hz, and 5 Hz) were dramatically higher in the 8 h group (P<0.01). Conclusions: For gMG patients, the facial and accessory nerve detection can improve the positive rate of RNS. Different muscles had various sensitivity to PB, and orbicularis oculi muscle seemed the least sensitive muscle to PB. For suspect MG patients in severe condition, only discontinuing PB medication for 8 h before low-frequency RNS testing can avoid the deterioration and also obtain similar positive rate.

[Correlation factors of 127 times pre-crisis state in patients with myasthenia gravis]

Objective: To investigate the clinical features of the Pre-Crisis State and analyze the correlated risk factors of Pre-Crisis State of myasthenia crisis. Methods: We included 93 patients with myasthenia gravis (MG) who experienced 127 times Pre-Crisis State between October 2007 and July 2016. Those patients were hospitalized in the MG specialize center, Department of Neurological Science, first Affiliated Hospital of Sun Yat-sen University. The information of the general situation, the clinical manifestations and the blood gas analysis in those patients were collected using our innovated clinical research form. Statistic methods were applied including descriptive analysis, univariate logistic analysis, multivariate correlation logistic analysis, etc. Results: (1)The typical features of MG Pre-Crisis State included: dyspnea (127 times, 100% not requiring intubation or non-invasive ventilation), bulbar-muscle weakness (121 times, 95.28%), the increased blood partial pressure of carbon dioxide (PCO(2)) (94 times, 85.45%), expectoration weakness (99 times, 77.95%), sleep disorders (107 times, 84.25%) and the infection (99 times, 77.95%). The occurrence of dyspnea in combination with bulbar-muscle weakness (P=0.002) or the increased blood PCO(2) (P=0.042) often indicated the tendency of crisis. (2) The MG symptoms which were proportion to the occurrence of crisis includes: bulbar-muscle weakness (P=0.028), fever (P=0.028), malnutrition (P=0.066), complications (P=0.071), excess oropharyngeal secretions (P=0.005) and the increased blood PCO(2) (P=0.007). The perioperative period of thymectomy would not increase the risk of crisis. Conclusions: Dyspnea indicates the occurrence of the Pre-Crisis State of MG. In order to significantly reduce the morbidity of myasthenia crisis, the bulbar-muscle weakness, the increased blood PCO(2), expectoration weakness, sleep disorders, infection & fever and excess oropharyngeal secretions should be treated timely.

Influence of different flow-triggering levels on the breathing effort of mechanically ventilated patients

BACKGROUND

Although a sensitive flow triggering (FT) level is supposed to be associated with reduced breathing effort, the incidence of autotriggering (AT) is likely to be increased. The actual effects of various FT levels on the work of breathing and occurrence of AT in mechanically ventilated patients are unknown. We investigated the effects of different FT levels (1-8 L/min) on breathing effort and incidence of AT in mechanically ventilated patients under pressure support ventilation using a Puritan-Bennett 840 ventilator.

METHODS

Eight FT levels were randomly studied in mechanically ventilated patients under pressure support ventilation. The triggering effort (pressure-time product of triggering, PTPtr) was assessed by quantitating a segment of the pressure-time product of the esophagus (PTPes). The total PTPes, inspiratory work of breathing (Wi) and P0.1 were determined.

RESULTS

Nine patients with appropriately recorded signals were included. The incidence of AT significantly decreased with increasing FT level (FT1, 1 L/min: 30.7%, FT8: 0.2%). PTPtr significantly increased with increasing FT level (0.020 ± 0.004 cmH2O • S in FT1 to 0.190 ± 0.017 cmH2O • S in FT8), but P0.1 remained similar. PTPtr accounted for only1-3% of total PTPes. Wi and PTPes were significantly lower only at FT1, but there was no significant difference in Wi and PTPes at different FT levels when AT breaths were excluded.

CONCLUSION

A higher FT level was associated with lower incidence of AT, but without a significant increase in breathing effort. A higher FT level may be more reasonable in mechanically ventilated patients with this particular ventilator.

Dried blood spots for the diagnosis and quantitation of HIV-1: stability studies and evaluation of sensitivity and specificity for the diagnosis of infant HIV-1 infection in Thailand

Molecular methods for HIV-1 infection using dried blood-spot (DBS) for HIV-1 CRF01_AE subtypes have not been fully optimized. In this study assays for HIV-1 diagnosis or quantitation were evaluated using infant DBS from Thailand. Paired DBS and whole blood samples from 56 HIV-1 CRF01_AE or B'-infected infants were tested for infant diagnosis using modified Amplicor DNA PCR and NucliSens RNA NASBA and an in-house real-time PCR assay. The Amplicor Monitor viral load (VL) assay, with modifications for DBS, was also evaluated. DBS VL were hematocrit corrected. Stability studies were done on DBS stored at -70 degrees C to 37 degrees C for up to 1 year. The DBS diagnostic assays were 96-100% sensitive and 100% specific for HIV-1 diagnosis. DBS HIV-1 VL were highly correlated with plasma VL when corrected using the actual or an assumed hematocrit factor (r(c)=0.88 or 0.93, respectively). HIV-1 DNA in DBS appeared to be more stable than RNA and could be detected after up to 9 months at most temperatures. DBS VL could be consistently determined when stored frozen. These results show that DBS can be used accurately instead of whole blood for the diagnosis of HIV-1 infection and VL quantitation, particularly if samples are appropriately stored.

Waveforms of the ductus venosus blood flow in normal human fetuses aged 8-38 weeks

BACKGROUND

We attempted to establish normal Doppler flow velocity waveform patterns in the human fetal ductus venosus (DV), and also to establish a standardized measurement technique.

METHODS

Ductus venosus blood flow was measured in a prospective study involving 545 fetuses aged between 8 and 38 weeks in utero, the mothers of whom received prenatal care in Kaohsiung Chang Gung Memorial Hospital in a 12-month period in 1998-1999. Several DV hemodynamic parameters were assessed, including peak systolic velocity (DVP), peak systolic/diastolic (S/D) ratio, time-averaged velocity (TAMX), maximum velocity during atrial contraction (DVM), pulsatility index (PI), Pourcelot's resistance index (RI), and fetal heartbeat (FHB).

RESULTS

Technically acceptable ductus venosus blood flow velocity waveform patterns were collected from 490 of 545 pregnant women (89.9%). The mean +/- SD value for the peak systolic DV velocity during the time period of 8 to 38 weeks in utero was 0.33 +/- 0.11 meters/sec (m/s), the TAMX being 0.24 +/- 0.09 m/s. The maximum velocity during atrial contraction was 0.15 +/- 0.09 m/s, and the peak S/D velocity ratio was 2.5 +/- 1.01. The PI, Pourcelot's RI and fetal heart beat were, 0.67(+/- 0.21), 0.64 (+/- 0.11), and 163.3 (+/- 18.82 bpm), respectively. Significant increases in DVP, TAMX, and DVM with advancing gestational age were established, and decreases in PI, RI, S/D, and FHB with advancing gestational age were also observed.

CONCLUSIONS

Further investigation of DV hemodynamics throughout pregnancy may enable a greater understanding of normal placental perfusion, the fetal venous return to the heart and associated cardiac function.

Prenatal sonographic appearance of Beare-Stevenson cutis gyrata syndrome: two- and three-dimensional ultrasonographic findings

Beare-Stevenson cutis gyrata syndrome is characterized by craniofacial anomalies, particularly craniosynostosis, ear defects, cutis gyrata, acanthosis nigricans, anogenit anomalies, skin tags, and prominent umbilical stump. The prenatal two- and three-dimensional ultrasonographic findings of this rare condition is reported. The detection was made at 32 weeks of gestation in a woman with polyhydramnios and fetal head anomaly. The ultrasound appearance and postnatal follow-up are presented.

First trimester diagnosis of holoprosencephaly and cyclopia with triploidy by transvaginal three-dimensional ultrasonography

We present the prenatal three-dimensional (3D) ultrasound findings in a case of holoprosencephaly and cyclopia at 11 weeks gestation. Only holoprosencephaly with missing cyclopia were initially diagnosed because suboptimal views of the fetal face were obtained with transvaginal two-dimensional (2D) ultrasonography due to fetal position. Chromosomes identified by analysis of a fluid sample from early amniocentesis demonstrated a triploidy (69, XXX), spontaneous fetal demise occurred at 12 weeks and the pregnancy was terminated. This case demonstrated the usefulness of transvaginal 3D ultrasonography in establishing the final diagnosis.

Maternal serum screening for down syndrome in pregnancies conceived by intra-uterine insemination

The purpose of our study was to assess the influence of intra-uterine insemination (IUI) on the results of maternal serum Down syndrome screening. 43 women with IUI pregnancies and 4507 healthy women who conceived were studied. Ovulation in IUI pregnancies was induced by clomiphene and/or human menopausal gonadotrophin (hMG). Maternal serum levels of free beta-human chorionic gonadotrophin (hCG) and alpha-fetoprotein (AFP) were measured for Down syndrome screening. It was considered screen-positive when the risk of Down syndrome was 1 in 270 or greater in the second trimester. The value of maternal serum AFP was significantly lower in the IUI group (median=0.760 MoM) than in the control group (median=1.050 MoM). However, the value of free beta-hCG was not significantly different between the two groups. The positive rate of maternal serum Down syndrome in IUI pregnancies was similar to that of the control group. Our results indicate that IUI pregnancy may be associated with a lower level of AFP, although the mechanism for this difference remains unknown.

Prenatal diagnosis of trisomy 20 mosaicism by maternal serum screening for Down syndrome

We report two cases of prenatally diagnosed trisomy 20 mosaicism associated with positive Down syndrome screening at 16 weeks' gestation. Both infants exhibited normal growth and mental development. These cases suggest that the multiple-marker screening test may play an important role in prenatal detection and diagnosis of chromosomal anomalies in addition to Down syndrome.

Retinal detachment in postpartum preeclampsia and eclampsia: report of two cases

Retinal detachment is an unusual complication of hypertensive disorder in pregnancy. It has been reported in 1% to 2% of patients with severe preeclampsia and in 10% of patients with eclampsia. Choroidal ischemia may be the cause of retinal detachment. We know that mild arteriolar spasm involving the bulbar conjunctival vessels has been observed in the normal pregnancy, but in pregnancy-induced hypertension the vasospasm may be severe and result in choroidal ischemia. Most patients with retinal detachment in pregnancy-induced hypertension have had full spontaneous resolution within a few weeks, and they did not have any sequelae. Medical treatment with antihypertensive drugs and steroids may be helpful. We report two rare cases of retinal detachment and persistent hypertension in association with postpartum eclampsia and post-cesarean section preeclampsia. These patients had normotension throughout pregnancy. Preeclampsia or eclampsia developed after delivery, and blurred vision, headache, and reduced vision accompanied serous retinal detachment. The serous retinal detachment disappeared within 3 weeks. Good outcomes were found in the follow-up examinations in both of these cases. For women who had been normotensive at the time of delivery and then complained in the postpartum period of blurred vision, headaches, nausea and vomiting, we should consider the possibility of retinal detachment and perform fundoscopy.

Population-based screening for hemochromatosis using phenotypic and DNA testing among employees of health maintenance organizations in Springfield, Missouri

BACKGROUND

Hemochromatosis reportedly affects 3 to 8 persons per 1,000 and is associated with an elevated risk of morbidity and mortality. We sought to ascertain its prevalence in a community and to assess the association between phenotype and genotype.

METHODS

All health maintenance organization employees were invited to participate in hemochromatosis screening using a repeated elevation of the transferrin saturation test as the case definition (> or = 50% in women and > or = 60% in men with no other cause). Iron overload from hemochromatosis was defined as serum ferritin concentration > or = 95th percentile and mobilizable iron > or = 99th percentile for age and sex, or hepatic iron index > or = 1.9. The HFE gene was analyzed for mutations.

RESULTS

Participation among employees was 28% (1,653 of 6,000); 83% were women. The prevalence of hemochromatosis was 8 per 1,000 (13 of 1,653), and the prevalence of iron overload from hemochromatosis was 4 per 1,000 (5 of 1,653). Compared with those who had no HFE mutation, the relative risk (RR) for hemochromatosis was greatest for C282Y homozygotes (RR = 147), compound heterozygotes (RR = 19), and H63D homozygotes (RR = 9). Overall, 38% of participants had at least one HFE mutation. Screening based on an initial elevated transferrin saturation test had the best sensitivity, whereas DNA testing offered the best specificity and predictive value positive for iron overload disease.

CONCLUSIONS

In this population, we found a greater than expected prevalence of hemochromatosis and demonstrated a clear association with the HFE genotype. Promotion of screening is complicated by controversies in case definition and the large number of persons who will be detected before they have clinically significant iron loading, in whom the risk of clinical disease is unknown. Larger screening studies in more diverse populations are necessary to characterize the burden of disease and to follow those at risk (based on HFE or iron status measures) to establish the natural history of hemochromatosis.

Prenatal diagnosis of de novo interstitial deletion of proximal 4q by maternal serum screening for Down syndrome

Deletion of the proximal portion of chromosome 4q is apparently rare. To our knowledge, prenatal diagnosis of the interstitial deletion of 4q12-21.1 has never been reported. We present a prenatal case of 4q deletion in association with a positive Down syndrome screening test of an elevated maternal serum free beta human chorionic gonadotrophin (beta-hCG) level. The prenatal sonogram revealed intra-uterine growth retardation (IUGR) and shortening of the femur. Facial dysmorphism included micrognathia, depressed nasal bridge and low-set ears, these anomalies were evident at the postnatal examination. All of the anomalies were consistent with those described in proximal 4q deletion syndrome. Our case suggests that chromosome studies may be indicated for patients with high maternal serum free beta-hCG and IUGR in the early second trimester.

Thermolabile methylenetetrahydrofolate reductase polymorphism (C677T) and total homocysteine concentration among African-American and white women

A polymorphism associated with a thermolabile variant (C677T) of the enzyme methylenetetrahydrofolate reductase has been associated with both elevated total homocysteine (tHcy) levels and risk for cardiovascular disease. Data from the Stroke Prevention in Young Women Study were used to determine the prevalence of the C677T genotype and to assess whether environmental factors modified the association between genotype and tHcy concentration. The C677T genotype prevalence was 80% -/-, 20% +/-, and 0% +/+ among 46 African-American women; and 39% -/-, 53% +/-, and 8% +/+ among 77 white women (P < 0.01). There was a trend toward higher tHcy levels in African-American women with the +/- genotype when compared with the -/- genotype (6.9 mumol/L vs 5.3 mumol/L respectively, p = 0.10); no association was found among the white women (6.0 mumol/L, -/-; 4.5 mumol/L, +/-; and 6.2 mumol/L, +/+; p = 0.67). Among African American women, those who smoked and were +/- genotype had the highest tHcy levels (8.0 mumol/L); while among white women, those who smoked and were -/- had the highest tHcy levels (8.1 mumol/L). Despite being hampered by a limited sample size, the thermolabile allele is significantly less common among African-American than white women. The association between genotype and tHcy concentration is influenced by smoking and multivitamin use.

Platelet glycoprotein receptor IIIa polymorphism P1A2 and ischemic stroke risk: the Stroke Prevention in Young Women Study

BACKGROUND AND PURPOSE

Platelet glycoprotein IIb/IIa (GpIIb-IIIa), a membrane receptor for fibrinogen and von Willebrand factor, has been implicated in the pathogenesis of acute coronary syndromes but has not been previously investigated in relation to stroke in young adults.

METHODS

We used a population-based case-control design to examine the association of the GpIIIa polymorphism P1A2 with stroke in young women. Subjects were 65 cerebral infarction cases (18 patients with and 47 without an identified probable etiology) 15 to 44 years of age from the Baltimore-Washington region and 122 controls frequency matched by age from the same geographic area. A face-to-face interview for vascular disease risk factors and a blood sample for the P1A2 allele and serum cholesterol were obtained from each participant. Logistic regression was used to estimate the odds ratio for one or more P1A2 alleles after adjustment for other risk factors.

RESULTS

Among cases and controls, the prevalence rates of one or more P1A2 alleles were 21% and 22% among blacks and 36% and 28% among whites, respectively. This genotype was significantly associated with hypertension only in black control subjects but otherwise not with any of the established vascular risk factors. The adjusted odds ratio for cerebral infarction of one or more P1A2 alleles was 1.1 (confidence interval [CI], 0.6 to 2.3) overall, 0.5 (CI, 0.1 to 7.1) among blacks, and 1.4 (CI, 0.5 to 3.7) among whites. For the cases with an identified probable etiology, the corresponding odds ratios were 3.0 (CI, 0.9 to 10.4) overall, 0.7 (CI, 0.1 to 7.1) among blacks, and 12.8 (CI, 1.2 to 135.0) among whites.

CONCLUSIONS

No association was found between the P1A2 polymorphism of GpIIIa and young women with stroke. However, subgroup analyses showed that the P1A2 polymorphism of GpIIIa appeared to be associated with stroke risk among white women, particularly those with a clinically identified probable etiology for their stroke. Further work with an emphasis on stroke subtypes and with multiracial populations is warranted.

Partial trisomy 13 [46,XY,dup(13)(q14-31)]: a case report

We report a fetus with partial trisomy 13 [46,XY,dup(13)(q14-31)] which was found during an amniocentesis performed due to the age of the mother. This duplication segment (13q 14-31) has not been reported in literature. The clinical features of our patient included cleft lip/palate, low set ears, depressed nasal bridge, hypertelorism, and epicanthal fold. After termination of the pregnancy, the fetus was sent for an autopsy. The autopsy report was compatible with the gross findings and no other abnormalities, including central nervous, cardiac, and renal system, were found. The level of maternal alpha-fetoprotein, 2.67 MoM, was opposite with the common phenomenon in complete trisomy 13.

Correlation between genotype and phenotype in hereditary hemochromatosis: analysis of 61 cases

This report assesses the degree of iron overload in a cohort of patients in relationship to the presence or absence of the recently described 845 G-->A (C282Y) and 187 C-->G (H63D) mutations in the HFE (HLA-H) gene. Sixty-one patients with hereditary hemochromatosis diagnosed either with liver biopsy or on clinical grounds were included in this analysis. Forty-one patients were homozygous for C282Y, the genotype considered to be characteristic of hereditary hemochromatosis. At the time of this analysis, 37 of these 41 patients had achieved a state of iron depletion and mobilizable iron was calculated: 19 had less than 4 grams. Twenty-five of these 41 patients had liver biopsies; 4 of these patients had a hepatic iron index less than 1.9. Of the 4 patients with a normal hepatic iron index, 3 had a quantitative hepatic iron of greater than 50 micromol/g dry weight, and one had an inadequate biopsy sample. These findings support our suspicion that individuals may have hereditary hemochromatosis and homozygous C282Y despite relatively low body iron stores. Five patients were compound heterozygotes for C282Y and H63D. Four of these patients underwent liver biopsy; two had a hepatic iron index greater than 1.9. a third patient had a hepatic iron index of 1.3 but a quantitative hepatic iron of 90.6 micromol/g dry weight. All patients were phlebotomized to a state of iron depletion and only one of these patients had a mobilizable iron greater than 4 grams. Three patients were homozygous for H63D; these patients had either a hepatic iron index >1.9 or greater than 4 grams of mobilizable iron. Patients with homozygous H63D and significant iron overload are not well described. Seven patients were heterozygous for either C282Y or H63D; 4 had significant iron overload but three did not. Five patients had no HFE mutations; one of these patients unequivocally has iron overload with a hepatic iron index of 4.4 We conclude that: (1) Identification of HFE mutations will be clinically useful in identifying patients with hereditary hemochromatosis, (2) Patient genotyping will help confirm a diagnosis of hereditary hemochromatosis in some patients with relatively low body iron stores, (3) Significant iron loading can occur in the absence of homozygous C282Y, adding to the evidence that genes other than HFE may be involved in iron loading, and (4) Homozygous H63D can be associated with significant iron overload.

Diagnosis of perinatal human immunodeficiency virus infection by polymerase chain reaction and p24 antigen detection after immune complex dissociation in an urban community hospital

Results of polymerase chain reaction (PCR) and p24 antigen detection after immune complex dissociation (p24-ICD) were compared with antibody results after 18 months of age for human immunodeficiency virus (HIV) diagnosis in 345 prospectively followed, perinatally exposed infants. Of 59 infected and 286 uninfected infants tested at 1-6 months of age, sensitivity and specificity were, respectively, 100% and > 97% for PCR and 90% and > 97% for p24-ICD. Testing was done on > or = 2 occasions in the first 6 months of life in 43 infected infants; 77% had > or = 2 positive results with the same test. Of these infants, 68% had 2 positive p24-ICD tests. In uninfected infants, 96% had only negative tests; none had > 1 positive. By 6 months, all uninfected infants with > or = 2 PCR results could have been diagnosed. HIV status can be determined by PCR by age 6 months in most HIV-exposed infants. p24-ICD should not be used alone, because of its lower sensitivity, but may be useful in areas without advanced laboratory support.

Late postnatal mother-to-child transmission of HIV-1 in Abidjan, Côte d'Ivoire

BACKGROUND

HIV-1 can be transmitted from an infected mother to her infant through breastfeeding, although the precise risk of transmission by this route is unknown. A long-term follow-up of children born to HIV-infected women in Abidjan, Côte d'Ivoire, has enabled us to estimate this risk.

METHODS

Children born to 138 HIV-1-seropositive women, 132 HIV-2-seropositive women, 69 women seroreactive to both HIV-1 and HIV-2, and 274 HIV-seronegative women were enrolled at birth and followed up for as long as 48 months. All children were breastfed (median duration 20 months). Blood samples for either or both HIV PCR and HIV serology were obtained at 1, 2, and 3 months of age, and every 3 months thereafter. Early HIV infection was defined as a positive HIV-1 PCR result obtained in the first 6 months of life. Late postnatal transmission was diagnosed when a child had a negative PCR at 3 or 6 months of age, followed by either or both a positive HIV-1 PCR at 9 months or older, or persistently positive HIV-1 serology at 15 months or older.

FINDINGS

82 children born to HIV-1-seropositive mothers and 57 children born to mothers seropositive for both HIV-1 and HIV-2 had PCR results for samples taken within the first 6 months. By 6 months of age, 23 (28%; 95% CI 19-39) of the 82 children born to HIV-1-seropositive mothers and ten (18%; 95% CI 9-30) of the 57 children born to dually seropositive mothers were HIV-1 infected. Among children whose PCR results were negative at or before age 6 months, and who were followed up beyond 6 months, an additional four (9%) of the 45 children born to HIV-1-seropositive mothers and two (5%) of the 39 children born to dually seropositive mothers became HIV infected. The estimated rates of late postnatal transmission, with account taken of loss to follow-up and the observed pattern of weaning, were 12% (95% CI 3-23) and 6% (0-14), respectively. One of the five children whose mothers seroconverted from HIV-negative to HIV-1, and one of seven children whose mothers seroconverted from HIV-2 to dual reactivity, became HIV-1 positive. No case of late postnatal transmission occurred in children born to HIV-2-positive or persistently HIV-negative mothers.

INTERPRETATION

Breastfed children born to mothers seropositive for HIV-1 alone or seropositive for HIV-1 and HIV-2 in Abidjan are at substantial risk of late postnatal transmission. Early cessation of breastfeeding at 6 months of age should be assessed as a possible intervention to reduce postnatal transmission of HIV.

Detection of HIV type 1 env subtypes A, B, C, and E in Asia using dried blood spots: a new surveillance tool for molecular epidemiology

Global surveillance of HIV-1 subtypes for genetic characterization is hampered by the biohazard of processing and the difficulties of shipping whole blood or cells from many developing country regions. We developed a technique for the direct automated sequencing of viral DNA from dried blood spot (DBS) specimens collected on absorbent paper, which can be mailed unrefrigerated in sturdy paper envelopes with low biohazard risk. DBS were collected nonrandomly from HIV-1-infected, mostly asymptomatic, patients in five Asian countries in 1991, and shipped via airmail or hand carried without refrigeration to Bangkok, and then transshipped to North America for processing. After more than 2 years of storage, including 6 months at ambient temperatures, proviral DNA in the DBS was amplified by nested PCR, and a 389-nucleotide segment of the C2-V3 env gene region was sequenced, from which 287 base pairs were aligned and subtyped by phylogenetic analysis with neighbor-joining and other methods. From southern India, there were 25 infections with subtype C and 2 with subtype A. From Myanmar (Burma), we identified the first subtype E infection, as well as six subtype BB, a distinct cluster within subtype B that was first discovered in Thailand and that has now appeared in China, Malaysia, and Japan. From southwest China, one BB was identified, while a "classical" B typical of North American and European strains was found in Indonesia. From Thailand, five DBS of ambiguous serotype were identified as three B, one BB, and one E. A blinded control serotype E specimen was correctly identified, but a serotype BB control was not tested. Most HIV-1 in southern India appears to be env subtype C, with rare A, as others have reported in western and northern India. The subtypes BB and E in Myanmar, and the BB in China, suggest epidemiological linkage with these subtypes in neighboring Thailand. DBS are a practical, economical technique for conducting large-scale molecular epidemiological surveillance to track the global distribution and spread of HIV-1 variants.

Estimating the timing of mother-to-child transmission of human immunodeficiency virus in a breast-feeding population in Kinshasa, Zaire

Breast-fed infants born to human immunodeficiency virus (HIV)-infected mothers in Kinshasa, Zaire, were monitored a mean of 18 months. HIV infection in infants was determined by polymerase chain reaction (PCR), HIV culture, or ELISA. PCR test results for HIV DNA on venous blood drawn from children ages 0-2 days and 3-5 months were used to estimate proportions of mother-to-child transmission and transmission risks during the intrauterine, intrapartum/early postpartum, and late postpartum periods. Among 69 HIV-infected children (26% of the cohort), 23% (95% confidence interval [CI], 14%-35%) were estimated to have had intrauterine, 65% (CI, 53%-76%) intrapartum/early postpartum, and 12% (CI, 5%-22%) late postpartum transmission. The estimated risks for intrauterine, intrapartum/early postpartum, and late postpartum infection, respectively, were 6% (16/261; CI, 4%-10%), 18% (45/245; CI, 14%-24%), and 4% (8/189; CI, 2%-8%). These results support earlier studies indicating that most transmission occurs during labor and delivery or in the early postpartum period and that the risk of HIV transmission through breast-feeding during the postpartum period is substantial.

5,10 Methylenetetrahydrofolate reductase genetic polymorphism as a risk factor for neural tube defects

Persons with a thermolabile form of the enzyme 5,10 methylenetetrahydrofolate reductase (MTHFR) have reduced enzyme activity and increased plasma homocysteine which can be lowered by supplemental folic acid. Thermolability of the enzyme has recently been shown to be caused by a common mutation (677C-->T) in the MTHFR gene. We studied 41 fibroblast cultures from NTD-affected fetuses and compared their genotypes with those of 109 blood specimens from individuals in the general population. 677C-->T homozygosity was associated with a 7.2 fold increased risk for NTDs (95% confidence interval: 1.8-30.3; p value: 0.001). These preliminary data suggest that the 677C-->T polymorphism of the MTHFR gene is a risk factor for spina bifida and anencephaly that may provide a partial biologic explanation for why folic acid prevents these types of NTD.

Dried blood spots collected on filter paper: an international resource for the diagnosis and genetic characterization of human immunodeficiency virus type-1

The collection of dried blood spots (DBS) on filter paper provides a powerful approach for the development of large-scale, population-based screening programs. DBS methods are particularly valuable in developing countries and isolated rural regions where resources are limited. Large numbers of field specimens can be economically collected and shipped to centralized reference laboratories for genetic and (or) serological analysis. Alternatively, the dried blood can be stored and used as an archival resource to rapidly establish the frequency and distribution of newly recognized mutations, confirm patient identity or track the origins and emergence of newly identified pathogens. In this report, we describe how PCR-based technologies are beginning to interface with international screening programmes for the diagnosis and genetic characterization of human immunodeficiency virus type 1 (HIV-1). In particular, we review recent progress using DBS specimens to resolve the HIV-1 infection status of neonates, monitor the genetic evolution of HIV-1 during early infancy and establish a sentinel surveillance system for the systematic monitoring of HIV-1 genetic variation in Asia.

A prospective population-based study of HIV perinatal transmission

OBJECTIVE

To estimate the perinatal HIV transmission rate and describe the natural history of infant HIV infection in a situation in which HIV status is known in more than 95% of delivering women.

DESIGN

A cohort of HIV-exposed infants born between 7 July 1987 and 30 June 1990, whose mothers were identified by routine voluntary universal HIV testing, were followed using clinical and laboratory measures.

SETTING

Grady Memorial Hospital, a major health-care site for individuals of lower socioeconomic status in Atlanta, Georgia, USA, with approximately 7000 deliveries per year.

PATIENTS

HIV-exposed infants (n = 165), 98% of whom were African American.

RESULTS

Annual maternal HIV seroprevalence increased from 0.58 to 0.86%. The annual proportion of HIV-positive women having a second delivery increased from 4.3 to 25%. Clinical outcome was known for 132 out of 165 infants (22 infected and 110 uninfected), the transmission rate was 17% (confidence interval, 11-24%). The rate declined to 11% by the third year of the study. Gestational growth, prematurity and mode of delivery were unrelated to infant outcome. There was a trend for intravenous drug use to be more common in mothers of infected infants (P = 0.08). After 35 months median follow-up of infected infants, eight out of 22 (36%) had an opportunistic infection (seven Pneumocystis carinii pneumonia); three out of 22 (14%) had lymphocytic interstitial pneumonia, and 10 out of 22 (45%) were asymptomatic or had only nonspecific symptoms. Cumulative mortality in infected infants was 9, 32 and 32% by 1, 2 and 3 years of age, respectively.

CONCLUSION

In this cohort of HIV-exposed infants, perinatal HIV transmission was 17% overall. Factors affecting the transmission rate and possible future changes in the rate require further study.

Biological, serological, and genetic characterization of HIV-1 subtype E isolates from northern Thailand

Twenty-three HIV-1 isolates were recovered from PBMCs from 26 HIV-1-seropositive individuals in northern Thailand. The viruses grew readily in human PBMCs but only 7 of 17 (41.2%) and 5 of 17 (29.4%) replicated and only at a low level in primary macrophages and in established T cell lines, respectively. By immunoblot assays, sera from Thai subjects were strongly reactive with gp120 from a Thailand isolate, moderately reactive with a Rwandan isolate, and weakly reactive with a North American strain. These three viruses represent, respectively, examples of subtypes E, A, and B as classified by the sequences of the envelope region. Serological assays indicated that broadly reactive rather than type-specific neutralizing activity was detected among these northern Thai sera. The majority of the sera (approximately 75%) neutralized a representative Thailand isolate and the Rwanda isolate but only 55% neutralized the North American strain. However, the difference was not statistically significant. The genetic analyses indicated that nearly all the Thai isolates were highly homogeneous and distinct from the North American/European consensus sequence (subtype B); they belong to subtype E. This is the first report providing biological, serological, and genetic characterization of HIV-1 strains from Thailand. The findings suggest these viruses were recently introduced into the country and that serological evaluation of viral strains needs to be considered along with genetic subtyping when developing an HIV-1 vaccine.

Lack of association between anti-V3 loop antibody and perinatal HIV-1 transmission in Kinshasa, Zaire, despite use of assays based on local HIV-1 strains

Maternal antibodies against the V3 loop principal neutralizing domain (PND) have been reported to protect against perinatal HIV-1 transmission. To study this association in an African city with a long-standing HIV epidemic and no established "consensus sequence" for the V3 loop region of gp120, we determined the DNA sequence for the V3 region of HIV-1 from 13 HIV-1-infected residents of Kinshasa, Zaire, and developed peptide enzyme immunoassays (EIAs) reflecting the V3 loop PND for those HIV-1 strains. Using the most broadly reactive locally derived V3 loop peptide in a limited-antigen EIA, there was no significant difference in the perinatal HIV-1 transmission risk between 64 women with anti-V3 loop antibody (transmission risk, 30%) and 104 women without anti-V3 loop antibody (transmission risk, 25%; p = 0.5); this finding was unchanged after we controlled for maternal AIDS and low birth weight. Although we used assays for V3 loop antibody based on local HIV-1 strains and evaluated a large number of mother-child pairs, we found no evidence that maternal anti-V3 loop PND antibody protects against perinatal HIV-1 transmission.

Genetic diversity of human immunodeficiency virus type 1 strains in Kinshasa, Zaire

The envelope (env) gene of human immunodeficiency virus type 1 (HIV-1) was amplified by polymerase chain reaction (PCR) from the peripheral blood mononuclear cells (PBMCs) of 14 HIV-1-infected women from Kinshasa, Zaire. Amplified DNA was directly sequenced with a primer specific for the HIV-1 env C2 region. The predicted amino acid sequences for the C2-V3 region for the 14 specimens are presented. The tetrapeptide sequence, GPGQ, located at the crown of the V3 loop, is conserved in all specimens. The same tetrapeptide sequence is present in the Zairian isolate MAL, but not in other published Zairian isolates (Z6, ELI, Z321, JY1, and NDK). Sequence comparison of the env C2-V3 region among the 14 specimens from Kinshasa revealed a 9-25% range of nucleotide divergence, with an average of 16%. Divergence between the 14 specimens and the Zairian isolates MAL, Z6, ELI, Z321, JY1, and NDK ranged from 13 to 31%. A range of 18-28% nucleotide sequence divergence was demonstrated between the 14 Kinshasa specimens and the North American isolate MN. These results demonstrate the importance of examining HIV-1 samples from diverse geographic origins in the development of effective HIV-1 vaccines.

Independent introduction of two major HIV-1 genotypes into distinct high-risk populations in Thailand

To investigate the genetic heterogeneity and epidemiological distribution of human immunodeficiency virus type 1 (HIV-1) in Thailand, we determined proviral sequences for 63 HIV-1-infected patients in various risk groups from all over the country between April and July, 1991. Two distinct genotypes of HIV-1, A and B, were found to segregate by mode of transmission. Of 29 sexually infected patients, 25 (86%) had HIV-1 of genotype A and 4 (14%) had genotype B. Among 29 injecting drug users, probably parenterally infected, only 7 (24%) had genotype A and 22 (76%) had genotype B. This segregation is unlikely to have arisen by chance (p < 0.001). No patient was found to have dual infection. Nucleotide divergence averaged 3.4% among genotype-A-infected patients and 3.5% among genotype-B-infected patients, but 22.0% between the genotypes. 37 of 40 isolates (both genotypes) had the GPGQ tetrapeptide at the tip of the V3 loop, which is common in African HIV-1 strains but rare in North American and European strains, where the GPGR motif predominates. These findings suggest that the waves of HIV-1 infection in injecting drug users and in sexually infected patients in Thailand may not be epidemiologically linked. The nucleotide divergence data point to the separate introductions of the two genotypes in Thailand. Further studies in Thailand and neighbouring countries will be useful in the design and selection of candidate HIV vaccines.

Highly specific V3 peptide enzyme immunoassay for serotyping HIV-1 specimens from Thailand

OBJECTIVE

To develop and evaluate a simple V3 peptide-based enzyme immunoassay (EIA) for large-scale serotyping of HIV-1 specimens from Thailand.

DESIGN

Serologic reactivities with synthetic peptides derived from the V3 loop of gp120 were used for typing HIV-1 specimens.

METHODS

Synthetic peptides PND-A and PND-B, derived from the consensus amino-acid sequences of the V3 loop of gp120 from two major genomic variants of HIV-1 in Thailand (A and B), were evaluated in an EIA on 61 Thai HIV-1 sera for which genotypes had been determined by polymerase chain reaction. The peptide EIA was then applied to sera from 188 HIV-1-infected patients, selected in non-random, convenience samples of known risk groups from four geographic regions of Thailand.

RESULTS

The sensitivities and specificities of PND-A and PND-B were 86% (30 out of 35) and 96% (25 out of 26) and 92% (24 out of 26) and 94% (33 out of 35), respectively, with 100% predictive values of a monoreactive positive test for both peptides. The assay classified 101 specimens as serotype A, 39 as serotype B, eight as serotype AB (dually reactive), and 40 as untypable (non-reactive). Excluding dual reactors and non-reactors, 92% (77 out of 84) of specimens from patients probably infected by sexual contact were serotype A; conversely, 76% (28 out of 37) of injecting drug users were serotype B.

CONCLUSION

The serologic results corroborated previous findings, in a smaller subset of samples, of an apparent segregation of viral subtypes by mode of transmission, suggesting two separate HIV-1 epidemics in Thailand. This peptide EIA could be a valuable epidemiologic tool in determining the dynamics of the rapid spread of HIV-1 in Thailand.

Lack of detectable human immunodeficiency virus infection in antibody-negative children born to human immunodeficiency virus-infected mothers

More than one-half of the children born to women with human immunodeficiency virus (HIV) infection are not infected with HIV. Most of these children, although born antibody-positive, lose maternal antibody and remain asymptomatic. However, it has been unclear how many antibody-negative children of HIV-infected women may truly be infected despite the loss of passively acquired maternal antibody. One hundred nine children who lost maternal antibody after birth to HIV-infected women recruited in four United States maternal HIV transmission studies were examined for HIV infection. Polymerase chain reaction (PCR) was used to determine whether children had HIV proviral DNA in peripheral blood mononuclear cells. A total of 268 samples from 109 children were tested. Clinical status and other laboratory findings were also evaluated. The median age at last follow-up was 25 months (range, 12 to 48 months). One hundred seven (98%) children were negative by PCR on all samples tested. None (95% confidence interval, 0.0 to 1.9%) of 109 children had a repeatedly positive PCR. Two children had single positive PCR results that could not be confirmed on subsequent testing. No other laboratory or clinical findings supported HIV infection in either of these children. The loss of HIV antibody in an asymptomatic child born to an HIV-infected woman strongly suggests that the child is not infected with HIV. Single positive PCR results, particularly in the absence of other clinical or laboratory evidence of HIV infection, should not be used alone to diagnose HIV infection.

Nonradioactive, colorimetric microplate hybridization assay for detecting amplified human immunodeficiency virus DNA

A nonradioactive, colorimetric microplate hybridization procedure was used to assay human immunodeficiency virus (HIV) DNA, amplified by the polymerase chain reaction (PCR). Under the PCR conditions used, four proviral copies per 150,000 cells were detected by amplifying a series of DNA mixtures that contained various copy numbers of HIV. Assays of PCR-amplified DNA from peripheral blood mononuclear cells of seronegative individuals yielded negative results (104 of 104), whereas samples from seropositive individuals yielded > 99% positive results (141 of 142). Similar results were obtained in a chemiluminescent assay with an acridinium ester-labeled probe and in a solution hybridization assay in which a 32P-labeled probe was used.

Detection of toxigenic Clostridium difficile in stool specimens by the polymerase chain reaction

Polymerase chain reaction (PCR) amplification of a segment of the toxin A gene was used to detect toxigenic Clostridium difficile directly from stool specimens of patients with antibiotic-associated diarrhea. Although PCR-inhibitory substances were recognized in DNA prepared from stool specimens, the inhibitory substances were eliminated by using an ion-exchange column after phenol-chloroform extraction. Eventually, 39 stool specimens were evaluated by PCR. PCR results for detection of toxigenic C. difficile were in complete agreement with cell culture assay results; all 12 PCR-positive stool specimens were positive by cytotoxin assay, and all 27 PCR-negative specimens were negative by cytotoxin assay. Toxigenic C. difficile was cultured from all PCR-positive specimens. These results suggest that PCR amplification may be an effective method for laboratory diagnosis of C. difficile-associated diarrhea and colitis.

Nonradioactive, colorimetric microplate hybridization assay for detecting amplified human immunodeficiency virus DNA

A nonradioactive, colorimetric microplate hybridization procedure was used to assay human immunodeficiency virus (HIV) DNA, amplified by the polymerase chain reaction (PCR). Under the PCR conditions used, four proviral copies per 150,000 cells were detected by amplifying a series of DNA mixtures that contained various copy numbers of HIV. Assays of PCR-amplified DNA from peripheral blood mononuclear cells of seronegative individuals yielded negative results (104 of 104), whereas samples from seropositive individuals yielded &gt; 99% positive results (141 of 142). Similar results were obtained in a chemiluminescent assay with an acridinium ester-labeled probe and in a solution hybridization assay in which a 32P-labeled probe was used.

Prevalence of HIV-1 and HIV-2 mixed infections in Côte d'Ivoire

We have investigated the cause of dual serological reactivity to human immunodeficiency virus (HIV) types 1 and 2, a common occurrence in West Africa. Serum specimens from 111 individuals from Côte d'Ivoire classified by commercial western blot as HIV-1 (n = 15), HIV-2 (32), and dually reactive (64) were further tested by more specific serological tests (a synthetic peptide enzyme immunoassay [Pepti-LAV 1/2] and western blots prepared from antigen in which oligomeric forms of the transmembrane protein were disrupted by trichloroacetic acid [WB-TCA]). Peripheral blood mononuclear cells were tested for HIV-1 and HIV-2 with the polymerase chain reaction (PCR) and virus culture. Of 104 samples that were concordant by both WB-TCA and Pepti-LAV, 82 (79%) were confirmed by PCR results. Virus culture was concordant with serology for specimens (35/38) in which any virus was detected. Our findings indicate that mixed HIV-1/HIV-2 infections are common in Côte d'Ivoire, and suggest that natural infection by one HIV type does not prevent heterologous infection.

Thermostable, salt tolerant, wide pH range novel chitobiase from Vibrio parahemolyticus: isolation, characterization, molecular cloning, and expression

A chitobiase gene from Vibrio parahemolyticus was cloned into plasmid pUC18 in Escherichia coli strain DH5 alpha. The plasmid construct, pC120, contained a 6.4 kb Vibrio DNA insert. The recombinant gene expressed chitobiase [EC 3.2.1.30] activity similar to that found in the native Vibrio. The enzyme was purified by ion exchange, hydroxylapatite and gel permeation chromatographies, and exhibited an apparent molecular weight of 80 kDa on SDS-polyacrylamide gel electrophoresis. Chitobiose and 6 more substrates, including beta-N-acetyl galactosamine glycosides, were hydrolyzed by the recombinant chitobiase, indicating its putative classification as an hexosaminidase [EC 3.2.1.52]. The enzyme was resistant to denaturation by 2 M NaCl, thermostable at 45 degrees C and active over a very unusual (for glycosyl hydrolases) pH range, from 4 to 10. The purified cloned chitobiase gave 4 closely focussed bands on an isoelectric focusing gel, at pH 4 to 6.5. The N-terminal 43 amino acid sequence shows no homology with other proteins in commercial databanks or in the literature, and from its N-terminal sequence, appears to be a novel protein, unrelated in sequence to chitobiases from other Vibrios reported and unrelated to hexosaminidases from other organisms.

Zidovudine-interferon-alpha combination therapy in patients with advanced human immunodeficiency virus type 1 infection: biphasic response of p24 antigen and quantitative polymerase chain reaction

In an open-label dose-ranging pilot trial, 13 homosexual men with human immunodeficiency virus type 1 (HIV-1) p24 antigenemia after at least 6 weeks of zidovudine monotherapy were continued on zidovudine and given interferon-alpha, 1.25-7.5 x 10(6) units/m2 subcutaneously three times/week. Plasma p24 antigen levels demonstrated a biphasic response, falling initially in 11 patients by a mean of 50% (95% confidence interval, 36%-64%; P = .001) at a median of 11 weeks, but rising steadily thereafter (P = .001). CD4+ cell counts fell by a mean of 7.1 cells/mm3/week (P = .01). Higher initial CD4+ counts predicted greater p24 antigen reductions. At higher interferon doses no greater reductions in p24 antigen occurred, but side effects were more severe and CD4+ lymphocyte counts fell faster. Polymerase chain reaction quantification of HIV-1 DNA in 3 patients showed a biphasic pattern paralleling the p24 antigen response. In sum, although evidence of short-term effects was found, the combination showed no evidence of lasting antiviral activity beyond that achieved with zidovudine alone in patients with advanced HIV-1 infection.

Molecular epidemiology of HIV transmission in a dental practice

Human immunodeficiency virus type 1 (HIV-1) transmission from infected patients to health-care workers has been well documented, but transmission from an infected health-care worker to a patient has not been reported. After identification of an acquired immunodeficiency syndrome (AIDS) patient who had no known risk factors for HIV infection but who had undergone an invasive procedure performed by a dentist with AIDS, six other patients of this dentist were found to be HIV-infected. Molecular biologic studies were conducted to complement the epidemiologic investigation. Portions of the HIV proviral envelope gene from each of the seven patients, the dentist, and 35 HIV-infected persons from the local geographic area were amplified by polymerase chain reaction and sequenced. Three separate comparative genetic analyses--genetic distance measurements, phylogenetic tree analysis, and amino acid signature pattern analysis--showed that the viruses from the dentist and five dental patients were closely related. These data, together with the epidemiologic investigation, indicated that these patients became infected with HIV while receiving care from a dentist with AIDS.

Transmission of human immunodeficiency virus in a dental practice

OBJECTIVE

To determine if patients of a dentist with the acquired immunodeficiency syndrome (AIDS) became infected with human immunodeficiency virus (HIV) during their dental care and, if so, to identify possible mechanisms of transmission.

DESIGN

Retrospective epidemiologic follow-up of the dentist, his office practice, and his former patients.

SETTING

The practice of a dentist with AIDS in Florida.

PARTICIPANTS

A dentist with AIDS, his health care providers and employees, and former patients of the dentist, including eight HIV-infected patients.

MEASUREMENTS

Identification of risks for HIV transmission (if present), degree of genetic relatedness of the viruses, and identification of infection control and other office practices.

RESULTS

Five of the eight HIV-infected patients had no confirmed exposures to HIV other than the dental practice and were infected with HIV strains that were closely related to those of the dentist. Each of the five had invasive dental procedures, done by the dentist after he was diagnosed with AIDS. Four of these five patients shared visit days (P greater than 0.2). Breaches in infection control and other dental office practices to explain these transmissions could not be identified.

CONCLUSION

Although the specific incident that resulted in HIV transmission to these patients remains uncertain, the epidemiologic evidence supports direct dentist-to-patient transmission rather than a patient-to-patient route.

A prospective study of infants of human immunodeficiency virus seropositive and seronegative women with a history of intravenous drug use or of intravenous drug-using sex partners, in the Bronx, New York City

A prospective study was conducted in the Bronx, New York, of 70 infants of human immunodeficiency virus (HIV)-infected (n = 33) and uninfected (n = 37) mothers who had a history of intravenous drug use or of intravenous drug-using sex partners. Infants were observed from birth to a median age of 23 months (range 3 to 54 months). HIV infection was confirmed in seven infants (21%) of seropositive mothers; six developed HIV disease, with symptoms observed in the first year. Of these, three died (3, 9, and 36 months) of HIV-related causes; 3 of 4 survivors were greater than 25 months of age. HIV symptoms preceded or were concurrent with abnormalities in T-lymphocyte subsets; postneonatal polymerase chain reaction confirmed HIV infection in five infants with symptoms and one without symptoms. Among infants of seropositive mothers, seven without laboratory evidence of HIV (including polymerase chain reaction) had findings suggestive of HIV infection, including persistent generalized lymphadenopathy, hepatosplenomegaly, oral candidiasis, parotitis, and inverted T-lymphocyte ratios. These findings were not observed in infants of seronegative mothers. Although the presence of HIV proviral sequences was associated with HIV disease, the observation of indeterminate symptoms in at-risk infants indicates the importance of long-term clinical follow-up to exclude HIV infection. Disease manifestations in comparable infants of seronegative mothers are important for assessment of the impact of maternal drug use, development of specific clinical criteria for early diagnosis of HIV and eligibility for antiretroviral therapy.

Human chromosome-dependent and -independent pathways for HIV-2 trans-activation

Human immunodeficiency virus (HIV types 1 and 2) replication is controlled by the interaction of viral-encoded regulatory proteins and host cellular proteins with the viral long terminal repeat (LTR). The presence of HIV-1 and HIV-2 trans-activator proteins, tat1 and tat2, respectively, greatly increases viral gene expression from their homologous LTRs. It is unclear if the cellular factors that support tat1-directed trans-activation of the HIV-1 LTR are the same for tat2 trans-activation of the HIV-2 LTR. Human-Chinese hamster ovary hybrid cell clones were used to probe for human chromosomes involved in regulating HIV-1 and HIV-2 tat-directed transactivation. DNA transfection experiments showed that the presence of human chromosome 12 in human-hamster hybrid clones was necessary for high-level tat-directed trans-activation of the HIV-1 and -2 LTR. Cross-trans-activation of the HIV-2 LTR by tat1 was found to be chromosome 12 independent. In addition, chromosome 12 did not support trans-activation of another human retrovirus (human T-cell leukemia virus type I). Our results suggest that HIV-1 and -2 have evolved to employ a cellular pathway(s) encoded on human chromosome 12 for supporting homologous tat-directed trans-activation. Trans-activation of the HIV-2 LTR by tat1 in chromosome 12-minus cells suggests that multiple cellular pathways can be recruited to trans-activate the HIV-2 LTR and that these pathways may have been important in an HIV-like progenitor virus.

Use of UV irradiation to reduce false positivity in polymerase chain reaction

UV irradiation provides a simple and efficient way to minimize contamination or false positivity which often occurs in laboratories performing routine PCR tests. Here, we characterize several parameters of the effect of UV irradiation on DNA template, primers, deoxynucleoside triphosphate and Taq polymerase. UV irradiation of DNA results in the formation of pyrimidine dimers and thus prevents them from being effective templates in subsequent PCR. Reduction of the HIV DNA templates in polypropylene microcentrifuge tubes by more than 1000-fold can be achieved by UV irradiation. The sensitivity of the primers is sequence- and concentration-dependent. Oligonucleotides with neighboring thymine bases are more susceptible to UV than those without. Taq polymerase is highly UV sensitive, whereas deoxynucleotide triphosphate is relatively UV resistant.