Offering ART refill through community health workers versus clinic-based follow-up after home-based same-day ART initiation in rural Lesotho: The VIBRA cluster-randomized clinical trial

BACKGROUND

Community-based antiretroviral therapy (ART) dispensing by lay workers is an important differentiated service delivery model in sub-Sahara Africa. However, patients new in care are generally excluded from such models. Home-based same-day ART initiation is becoming widespread practice, but linkage to the clinic is challenging. The pragmatic VIBRA (Village-Based Refill of ART) trial compared ART refill by existing lay village health workers (VHWs) versus clinic-based refill after home-based same-day ART initiation.

METHODS AND FINDINGS

The VIBRA trial is a cluster-randomized open-label clinical superiority trial conducted in 249 rural villages in the catchment areas of 20 health facilities in 2 districts (Butha-Buthe and Mokhotlong) in Lesotho. In villages (clusters) randomized to the intervention arm, individuals found to be HIV-positive during a door-to-door HIV testing campaign were offered same-day ART initiation with the option of refill by VHWs. The trained VHWs dispensed drugs and scheduled clinic visits for viral load measurement at 6 and 12 months. In villages randomized to the control arm, participants were offered same-day ART initiation with clinic-based ART refill. The primary outcome was 12-month viral suppression. Secondary endpoints included linkage and 12-month engagement in care. Analyses were intention-to-treat. The trial was registered on ClinicalTrials.gov (NCT03630549). From 16 August 2018 until 28 May 2019, 118 individuals from 108 households in 57 clusters in the intervention arm, and 139 individuals from 130 households in 60 clusters in the control arm, were enrolled (150 [58%] female; median age 36 years [interquartile range 30-48]; 200 [78%] newly diagnosed). In the intervention arm, 48/118 (41%) opted for VHW refill. At 12 months, 46/118 (39%) participants in the intervention arm and 64/139 (46%) in the control arm achieved viral suppression (adjusted risk difference -0.07 [95% CI -0.20 to 0.06]; p = 0.256). Arms were similar in linkage (adjusted risk difference 0.03 [-0.10 to 0.16]; p = 0.630), but engagement in care was non-significantly lower in the intervention arm (adjusted risk difference -0.12 [-0.23 to 0.003]; p = 0.058). Seven and 0 deaths occurred in the intervention and control arm, respectively. Of the intervention participants who did not opt for drug refill from the VHW at enrollment, 41/70 (59%) mentioned trust or conflict issues as the primary reason. Study limitations include a rather small sample size, 9% missing viral load measurements in the primary endpoint window, the low uptake of the VHW refill option in the intervention arm, and substantial migration among the study population.

CONCLUSIONS

The offer of village-based ART refill after same-day initiation led to similar outcomes as clinic-based refill. The intervention did not amplify the effect of home-based same-day ART initiation alone. The findings raise concerns about acceptance and safety of ART delivered by lay health workers after initiation in the community.

TRIAL REGISTRATION

Registered with Clinicaltrials.gov (NCT03630549).

Home-based oral self-testing for absent and declining individuals during a door-to-door HIV testing campaign in rural Lesotho (HOSENG): a cluster-randomised trial

BACKGROUND

In sub-Saharan Africa, home-based HIV testing is validated and accepted, but coverage is low because household members are often absent during home-based testing campaigns. We aimed to measure the effect of a secondary distribution of oral-fluid HIV self-tests on coverage during home-based testing in rural Lesotho.

METHODS

The Home-Based Self-Testing (HOSENG) trial was a cluster-randomised, non-blinded superiority trial in rural villages in the catchment area of 20 health facilities of two districts in Lesotho (Butha-Buthe and Mokhotlong). Eligible villages had a consenting village chief and at least one registered village health worker; eligible households had a consenting representative aged 18 years or older. The HOSENG trial provided a recruitment platform for the interlinked Village-Based Refill of Antiretroviral Therapy (VIBRA) trial. Villages were randomly assigned 1:1:1:1 with block sizes of four to one of four groups: VIBRA control and HOSENG control; VIBRA control and HOSENG intervention; VIBRA intervention and HOSENG control; and VIBRA intervention and HOSENG intervention. Randomisation was stratified by district, village size, and access to the nearest health facility. An independent statistician was responsible for the computer-generated randomisation list. In the intervention group, oral-fluid HIV self-tests were left for absent or declining household members (aged ≥12 years) during a home visit from the HIV testing campaign team. One present household member was trained on self-test use. Distributed self-tests were followed up by village health workers. In control village clusters, absent or declining household members were referred to the clinic for HIV testing. The primary outcome was HIV testing coverage among all household members aged 12 years or older within 120 days, defined as a confirmed HIV test result or known status, reported in testing registers at the health facilities or on the follow-up forms of the village health worker. Adjusted random-effects logistic regression with individuals as the unit of analysis was used. This trial is registered with ClinicalTrials.gov, NCT03598686.

FINDINGS

Between July 26, 2018, and Dec 12, 2018, 3091 consenting households with 7816 household members aged 12 years or older were enrolled and randomly assigned (intervention: 57 village clusters, 1620 households, 4174 household members; control: 49 village clusters, 1471 households, 3642 household members). In the control group, 38 (3%) of 1455 initially absent or declining household members tested at a clinic within 120 days. In the intervention group, 841 (53%) of 1601 initially absent or declining household members had a confirmed status within 120 days; 12 (1%) of 841 tested at the clinic and 829 (99%) used their self-test kit. This resulted in a testing coverage of 2201 (60%) of 3642 in the control group versus 3386 (81%) of 4174 in the intervention group (odds ratio 3·00 [95% CI 2·52-3·59]; p<0·0001).

INTERPRETATION

Secondary distribution of oral-fluid HIV self-tests during home-based testing increases testing coverage substantially and thus presents a promising add-on during testing campaigns.

FUNDING

Swiss National Science Foundation.

"If it is left, it becomes easy for me to get tested": Use of oral self-tests and community health workers to maximize the potential of home-based HIV testing among adolescents in Lesotho

INTRODUCTION

Home-based HIV testing fails to reach high coverage among adolescents and young adults (AYA), mainly because they are often absent during the day of home-based testing. ADORE (ADolescent ORal tEsting) is a mixed-method nested study among AYA in rural Lesotho, measuring the effect of home-based secondary distribution of oral HIV self-tests (HIVST) on coverage, as well as exploring how AYA perceive this HIV self-testing model.

METHODS

ADORE study was nested in a cluster-randomized trial. In intervention village-clusters, oral HIVST were left for household members who were absent or declined testing during a testing campaign. One present household member was trained on HIVST use. Distributed HIVST were followed up by village health workers (VHW). In control clusters no self-tests were distributed. The quantitative outcome was testing coverage among AYA (age 12 to 24) within 120 days, defined as a confirmed HIV test result or known status, using adjusted random-effects logistic regression on the intention-to-treat population. Qualitatively, we conducted in-depth interviews among both AYA who used and did not use the distributed HIVST.

RESULTS

From July 2018 to December 2018, 49 and 57 villages with 1471 and 1620 consenting households and 1236 and 1445 AYA in the control and intervention arm, respectively, were enrolled. On the day of the home-visit, a testing coverage of 37% (461/1236) and 41% (596/1445) in the control and the intervention arm, respectively, were achieved. During the 120 days follow-up period, an additional 23 and 490 AYA in control and intervention clusters, respectively, knew their status. This resulted in a testing coverage of 484/1236 (39%) in the control versus 1086/1445 (75%) in the intervention arm (aOR 8.80 [95% CI 5.81 to 13.32]; p < 0.001). 21 interviews were performed. Personal assistance after the secondary distribution emerged as a key theme and VHWs were generally seen as a trusted cadre.

CONCLUSIONS

Secondary distribution of HIVST for AYA absent or refusing to test during home-based testing in Lesotho resulted in an absolute 36% increase in coverage. Distribution should, however, go along with clear instructions on the use of the HIVST and a possibility to easily access more personal support.

VIBRA trial - Effect of village-based refill of ART following home-based same-day ART initiation vs clinic-based ART refill on viral suppression among individuals living with HIV: protocol of a cluster-randomized clinical trial in rural Lesotho

BACKGROUND

There is a need for evaluating community-based antiretroviral therapy (ART) delivery models to improve overall performance of HIV programs, specifically in populations that may have difficulties to access continuous care. This cluster-randomized clinical trial aims to evaluate the effectiveness of a multicomponent differentiated ART delivery model (VIBRA model) after home-based same-day ART initiation in remote villages in Lesotho, southern Africa.

METHODS/DESIGN

The VIBRA trial (VIllage-Based Refill of ART) is a cluster-randomized parallel-group superiority clinical trial conducted in two districts in Lesotho, southern Africa. Clusters (i.e., villages) are randomly assigned to either the VIBRA model or standard care. The clusters are stratified by district, village size, and village access to the nearest health facility. Eligible individuals (HIV-positive, aged 10 years or older, and not taking ART) identified during community-based HIV testing campaigns are offered same-day home-based ART initiation. The intervention clusters offer a differentiated ART delivery package with two features: (1) drug refills and follow-ups by trained and supervised village health workers (VHWs) and (2) the option of receiving individually tailored adherence reminders and notifications of viral load results via SMS. The control clusters will continue to receive standard care, i.e., collecting ART refills from a clinic and no SMS notifications. The primary endpoint is viral suppression 12 months after enrolment. Secondary endpoints include linkage to and engagement in care. Furthermore, safety and cost-effectiveness analyses plus qualitative research are planned. The minimum target sample size is 262 participants. The statistical analyses will follow the CONSORT guidelines. The VIBRA trial is linked to another trial, the HOSENG (HOme-based SElf-testiNG) trial, both of which are within the GET ON (GETing tOwards Ninety) research project.

DISCUSSION

The VIBRA trial is among the first to evaluate the delivery of ART by VHWs immediately after ART initiation. It assesses the entire HIV care cascade from testing to viral suppression. As most countries in sub-Saharan Africa have cadres like the VHW program in Lesotho, this model-if shown to be effective-has the potential to be scaled up. The system impact evaluation will provide valuable cost estimations, and the qualitative research will suggest how the model could be further modified to optimize its impact.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT03630549 . Registered on 15 August 2018.

The HOSENG trial - Effect of the provision of oral self-testing for absent and refusing individuals during a door-to-door HIV-testing campaign on testing coverage: protocol of a cluster-randomized clinical trial in rural Lesotho

BACKGROUND

HIV-testing coverage remains below the targeted 90% despite efforts and resources invested. Home-based HIV-testing is a key approach endorsed by the World Health Organization (WHO), especially to reach individuals who might not seek testing otherwise. Although acceptance of testing during such campaigns is high, coverage remains low due to absent household members. This cluster-randomized trial aims to assess increase in testing coverage using oral HIV self-testing (HIVST) among individuals who are absent or decline testing during home-based HIV-testing.

METHODS

The HOSENG (HOme-based SElf-testiNG) trial is a cluster-randomized, parallel-group, superiority trial in two districts of Lesotho, Southern Africa. Clusters are stratified by district, village size, and village access to the nearest health facility. Cluster eligibility criteria include: village is in catchment area of one of the study facilities, village authority provides consent, and village has a registered, capable, and consenting village health worker (VHW). In intervention clusters, HIV self-tests are provided for eligible household members who are absent or decline HIV-testing in the presence of the campaign team. In control clusters, standard of care for absent and refusing individuals applies, i.e., referral to a health facility. The primary outcome is HIV-testing coverage among individuals aged 12 years or older within 120 days after enrollment. Secondary objectives include HIV-testing coverage among other age groups, and uptake of the different testing modalities. Statistical analyses will be conducted and reported in line with CONSORT guidelines. The HOSENG trial is linked to the VIBRA (Village-Based Refill of ART) trial. Together, they constitute the GET ON (GETting tOwards Ninety) research project.

DISCUSSION

The HOSENG trial tests whether oral HIVST may be an add-on during door-to-door testing campaigns towards achieving optimal testing coverage. The provision of oral self-test kits, followed up by VHWs, requires little additional human resources, finances and logistics. If cost-effective, this approach should inform home-based HIV-testing policies not only in Lesotho, but in similar high-prevalence settings.

TRIAL REGISTRATION

ClinicalTrials.gov, (ID: NCT03598686 ). Registered on 25 July 2018. More information is available at www.getonproject.wordpress.com .

Rodent p53 suppresses the transforming activity of the activated Neu oncogene by modulating the Basal promoter activity of Neu

The rat neu oncogene encodes a dominant transforming oncogene. The mouse wild-type p53 suppresses the transforming activity of the neu oncogene while different p53 mutants demonstrate varying ability to repress neu-induced transformation. Suppression of neu-transforming activity is due to inhibition of transcription. Deletion analysis of the rat neu promoter shows that p53 represses the basal promoter activity of neu. Therefore, rodent p53 suppresses the transforming potential of neu by inhibiting transcription from the basal promoter of neu.

Acne vaccines targeting Propionibacterium acnes

Acne vulgaris is one of the most common skin diseases and can affect a large number of individuals at some point in their lives. Though the disease is multi-factorial, the Gram-positive, anaerobic bacterium Propionibacterium acnes (P. acnes), a member of resident skin microflora, is implicated in acne inflammation and associated with acne lesions. Common treatments such as antibiotic or benzoyl peroxide nonspecifically reduce bacteria population on the skin, which may disrupt homeostasis and cause further complications such as promoting growth of antibiotic-resistant bacteria strains. A component vaccine and an inactivated whole bacteria vaccine are made to target specifically P. acnes. The component vaccine targeting P. acnes surface sialidase and heat-inactivated P. acnes vaccine have both been shown to reduce P. acnes- induced inflammation in vivo and neutralize P. acnes in vitro, suggesting their potentials as new treatment for acne vulgaris. To facilitate acne studies, a bioengineering approach was utilized to design a new human acne model using tissue chamber. The tissue chamber of human sebocytes is shown to produce in mice a microenvironment similar to human acne inflammation. This approach can also be utilized in future studies in developing therapeutic acne vaccines and designing possible combined treatment of acne vaccine with alternative acne treatments.

[Acute scrotum in children]

AIMS

To evaluate the frequency, to identify the aetiologies of the acute scrotum and to describe their treatment in children.

MATERIAL AND METHOD

Fifty seven children treated for acute scrotum in the paediatric surgery department of the Tokoin teaching hospital (Lomé) between January 2003 to December 2007 were studied.

RESULTS

The frequency of acute scrotum was 5.80%. The average age was of 4.75 years (range: 7 days to 15 years). The aetiologies were: incarcerated inguino scrotal hernia (49.12%); spermatic cord torsion (29.83%); epididymo-orchitis (17.54%) and testicular trauma (3.51%). The delay of treatment was superior of 72 hours in 49.12%. The pain and the increase of the volume of the scrotum were present in all the patients. The emergency operation was performed in the spermatic cord torsion and the testicular trauma. The medical treatment was performed in the epididymo-orchitis cases. The patients presenting an incarcerated inguino-scrotal hernia benefited from a surgical cure in a delay of eight days after the acute episode. The operative continuations were in any cases simple.

CONCLUSION

The diagnosis and the treatment must be precocious in the acute scrotum in order to avoid possible complications.

Pharmacokinetics, metabolism, excretion and plasma protein binding of 14C-levofloxacin after a single oral administration in the Rhesus monkey

Levofloxacin's metabolism, excretion, and in vitro plasma protein binding, together with its pharmacokinetics, were studied in the Rhesus monkey in support of an anthrax efficacy study in this species. Three males and three female Rhesus monkeys were dosed with a single oral dose of 14C-levofloxacin at 15 mg kg-1 (2 MBq kg-1). Following dose administration, blood samples were collected up to 48 h post-dose, and urine and faeces were quantitatively collected up to 168 h post-dose. Blood, plasma, urine, and faeces were analysed for total radioactivity. Metabolite profiling and identification was performed using radio-high-performance liquid chromatography (HPLC) and liquid chromatography coupled with tandem mass spectrometry detection (LC-MS/MS). Additionally, the plasma protein binding of levofloxacin was determined in vitro by means of equilibrium dialysis. Peak plasma levels of total radioactivity and levofloxacin were rapidly reached after oral administration with a total radioactivity blood: plasma ratio close to unity. The elimination half-life of levofloxacin was estimated at about 2 h. Total radioactivity was mainly excreted in urine (about 57-86% of the dose) with faecal excretion accounting for only a minor fraction of the total amount of excreted radioactivity (about 7.4-14.7%). In the plasma, the majority of total radioactivity was accounted for by levofloxacin. In addition, two minor metabolites, i.e. levofloxacin n-oxide and presumably a glucuronide conjugate of levofloxacin, were detected. In the urine, five components were found, with levofloxacin being the major component. Minor metabolites included desmethyl levofloxacin, levofloxacin n-oxide, and a glucuronide conjugate of levofloxacin. In the faeces, the major analyte was a polar metabolite, tentatively identified as a levofloxacin glucuronide. The in vitro plasma protein binding was low (on average 11.2%) and independent of concentration (1.0-10.0 microg ml-1). No sex differences were noted in any of the investigations. The present data indicated that the metabolism and excretion pattern, and also the in vitro plasma protein binding of levofloxacin in the Rhesus monkey, were comparable with those previously reported in man, hereby supporting the use of this animal species in the efficacy evaluation of levofloxacin against inhalation anthrax. The shorter half-life of levofloxacin in the Rhesus monkey relative to man (2 versus 7 h) prompted the development of an alternative dosing strategy for use in the efficacy study.

The absorption, metabolism, and excretion of the novel neuromodulator RWJ-333369 (1,2-ethanediol, [1-2-chlorophenyl]-, 2-carbamate, [S]-) in humans

RWJ-333369 (1,2-ethanediol, [1-2-chlorophenyl]-, 2-carbamate, [S]-; CAS Registry Number 194085-75-1) is a novel neuromodulator in clinical development for the treatment of epilepsy. To study the disposition of RWJ-333369, eight healthy male subjects received a single oral dose of 500 mg of (14)C-RWJ-333369. Urine, feces, and plasma were collected for analysis for up to 1 week after dosing. Radioactivity was mainly excreted in urine (93.8 +/- 6.6%) and much less in feces (2.5 +/- 1.6%). RWJ-333369 was extensively metabolized in humans, since only low amounts of parent drug were excreted in urine (1.7% on average) and feces (trace amounts). The major biotransformation pathways were direct O-glucuronidation (44% of the dose), and hydrolysis of the carbamate ester followed by oxidation to 2-chloromandelic acid, which was subsequently metabolized in parallel to 2-chlorophenyl glycine and 2-chlorobenzoic acid (mean percentage of the dose for the three acids together was 36%). Other routes were chiral inversion followed by O-glucuronidation (11%), and aromatic hydroxylation in combination with sulfate conjugation (5%). In plasma, unchanged drug accounted for 76.5% of the total radioactivity, with the R-enantiomer and the O-glucuronide of the parent drug as the only measurable plasma metabolites. With the use of very sensitive liquid chromatography-tandem mass spectrometry techniques, only traces of aromatic (pre)mercapturic acid conjugates were detected in urine (each <0.3% of the dose), suggesting a low potential for reactive metabolite formation. In conclusion, the disposition of RWJ-333369 in humans is characterized by virtually complete absorption, extensive metabolism, and unchanged drug as the only significant circulating species.

Design and analysis of VCSEL based twodimension wavelength converter

A novel two-dimensional vertical cavity surface emission laser (VCSEL) based wavelength converter is proposed. We developed a twodimensional transmission line laser model (TLLM) to analyze the proposed wavelength converter. This model takes into account Bragg reflectors by using the modified connecting matrix. Therefore, accurate and efficient modeling of the VCSEL structure is achieved. Extinction ratio of the output signal is investigated by considering input signal power, wavelength, facet reflectivity and cavity diameter.

Validation of the sterilization procedure of allogeneic avital bone transplants using peracetic acid-ethanol

Different procedures are available to inactivate bacteria and fungi, including their spores, as well as viruses in human bone transplants. The most efficient methods are considered to be gamma irradiation and thermal inactivation as well as chemical sterilization methods like the peracetic acid-ethanol treatment (PES). Following national and international standards or draft standards, the antimicrobial effectiveness of this procedure was evaluated. Due to the standardizable size as well as the clinical relevance, defatted human spongiosa cuboids (15x15x15 mm) served as model system. After treatment with PES for 2 and 4 hours, respectively, the titre of living micro-organisms was determined in the supernatant and the cuboid. A reduction in the titre of viable micro-organisms below the detection level (reduction factor >5 log10) was already achieved after an incubation time of 2 hours (Staphylococcus aureus, Enterococcus faecium, Pseudomonas aeruginosa, Bacillus subtilis, Clostridium sporogenes, Mycobacterium terrae, Candida albicans as well as spores of Bacillus subtilis). No viable micro-organisms could be detected in any of the PES-treated test cuboids. Spores of Aspergillus niger were also completely inactivated. The PES procedure proved to be a reliable method for the sterilization of human bone transplants derived from spongiosa.

Comparison of the efficacy of virus inactivation methods in allogeneic avital bone tissue transplants

Several procedures for inactivating viruses are used presently in the context of bone tissue transplants. Common methods used are gamma irradiation (25 kGy), treatment with moist heat (82.5 degrees C/15 min., lobator-sd2-system) as well as chemical sterilisation using peracetic acid-ethanol treatment (PES, 2% peracetic acid, 96% ethanol, Aqua [2:1:1], 200 mbar, agitation, 4 hours). Based on national and international guidelines, we tested the antivirucidal effectiveness of these methods in human bone transplants. Three enveloped viruses: human immunodeficiency virus type 2 (HIV-2), pseudorabies virus (PRV), bovine virus diarrhoea virus (BVDV), and three non-enveloped viruses were used: hepatitis A virus (HAV), poliovirus (PV-1), porcine/bovine parvovirus (PPV, BPV). Defatted spongiosa cuboids served as model in chemical treatment experiments, while cortical diaphyses were used in gamma irradiation experiments, and the effects of thermal treatment were tested in prepared femoral heads. The log(10) reduction was measured by cytopathogenic effects after virus titration (TCID(50)/mL). A dose of at least 33.9 kGy (bone model) at -30 +/- 5 degrees C was necessary to achieve a sufficient reduction (4 log(10) steps) of BPV, the most resistant one of all viruses investigated. Thermal treatment as well as PES treatment led to a reduction of virus titres by more than 4 log(10). Only HAV showed a reduction below 4 log(10) (2.87) with PES. After validation of the defatting step included for HAV-infected cells, a HAV-reduction of over 7 log(10) was found. All three sterilisation methods tested are recommended for bone transplant sterilisation, but only provided that additional safety measures (anamnestic informations, infectious serology, PCR in case of multiorgan donors) are taken.

Elevated topoisomerase I activity in cervical cancer as a target for chemoradiation therapy

OBJECTIVE

The aim of this study was to determine whether the activity of topoisomerase I (topo I), the target of the anti-neoplastic drug camptothecin (CPT), is elevated in cervical cancer and whether CPT can radiosensitize cervical tumors.

METHODS

The topo I activity of 11 normal cervix and 30 cervical carcinoma tumors was assayed by measuring the relaxation of supercoiled DNA. Subconfluent or postconfluent CaSki human cervical carcinoma cells were exposed to CPT (1-5000 ng/ml) and immediately X-irradiated (0-800 cGy). Cell survival was determined by clonogenic assay.

RESULTS

Mean topo I activity in cervical cancer (3.0 +/- 0.06 h(-1)) was significantly greater than in normal cervix tissue (0.29 +/- 0.06 h(-1)). Stage 3 and 4 cervical carcinoma specimens displayed a trend of greater topo I activity (5.88 +/- 3.7 h(-1)) than stage 1 and 2 tumors (2.57 +/- 0.47 h(-1)). No correlation between topo I protein levels and catalytic activity was found. Combined treatment of subconfluent CaSki cells with CPT and ionizing radiation resulted in additive killing of cells. Combined treatment of postconfluent CaSki cells with low doses of radiation (200 and 400 cGy) and 1 or 10 ng/ml CPT for 2 or 48 h produced significant cytotoxicity compared to CPT or radiation alone, which were ineffective at these doses.

CONCLUSIONS

Topo I activity is elevated in cervical cancer compared to normal cervix. The radiosensitivity of noncycling cells within cervical tumors may be increased by simultaneous treatment with low doses of CPT or other topo I inhibitors.

Further studies on thermal resistance of bovine parvovirus against moist and dry heat

To supplement the results of thermal resistance of bovine parvovirus (Haden strain, BPV) published previously, we carried out assays at 60 degrees C (moist heat) to compare the thermal resistance of BPV with that of hepatitis B-virus (HBV). What we know about the resistance of HBV at a temperature of 60 degrees C is mainly based on data collected within the context of blood product pasteurization. The results suggest that at a temperature of 60 degrees C, BPV shows thermal resistance comparable to HBV. Thus, BPV--which is easier to handle--can be considered a good test virus to verify the efficacy of thermal disinfection techniques against HBV. BPV is very resistant against dry heat of 100 degrees C, the inactivation largely depending upon the residual moisture of the lyophilisate. Reducing the residual moisture from 2% to less than 1%, the exposure time has to be prolonged by ca. 2.5 times to achieve the same virucidal effect.

Virus safety of avital bone tissue transplants: evaluation of sterilization steps of spongiosa cuboids using a peracetic acid-methanol mixture

The aim of this study was to validate the virus-inactivating/eliminating capacity of the manufacturing process of spongiosa cuboids. Both the sterilization step with peracetic acid (PAA)/ethanol and the defatting step of bones with chloroform/methanol (2:1, v/v) were investigated. Relevant enveloped, non-enveloped, and model viruses belonging to different virus families were included in the investigation: human immunodeficiency virus type 2 (HIV-2), hepatitis A virus (HAV), poliovirus (PV-1), pseudorabies virus (PRV), porcine parvovirus (PPV), and bovine virus diarrhoea virus (BVDV). Treatment of virus-spiked spongiosa cuboids for 4 hours at room temperature (RT) with 1% PAA/24% ethanol (PES) efficiently inactivated most viruses. Titres were reduced by more than 4 log(10)with the exception of HAV. The defatting step with chloroform/methanol reduced HAV titres by a factor of >/=7.0 log(10). From these results it can be concluded that the treatment of spongiosa cuboids with (i) chloroform/methanol and (ii) 1% PAA/24% ethanol solution leads to a virus-safe medicinal product.

Herpesvirus-like infection in a raccoon (Procyon lotor)

During March 1990, a subadult raccoon found dead in northeastern Pennsylvania (USA) had gross lesions of multifocal hepatitis. Microscopically, multifocal randomly distributed areas of acute necrosis with intranuclear viral inclusions were seen in liver, spleen, adrenal glands, and tongue. Ultrastructural and immunoperoxidase results of formalin fixed liver were compatible with herpesvirus infection. This virus could be unique to the raccoon or may have been acquired from another species.

A novel adenylyl cyclase sequence cloned from the human erythroleukemia cell line

The polymerase chain reaction (PCR) was used to detect several forms of adenylyl cyclase (AC's) expressed in human erythroleukemia (HEL) cells. Degenerate oligonucleotide primers were synthesized based on the conserved sequences in the C2a area of the AC's. HEL cells were found to contain mRNA for type III and type VI AC. In addition, a novel AC message was identified. The cloned sequence, excluding primer areas, represented 69 amino acids with most similarity to rat AC's II and IV. Northern analysis of RNA from HEL cells demonstrated a 6.7 kilobase message. RNase protection assays revealed that in HEL cells the novel AC mRNA was dominant compared to types III and VI. Human embryonic kidney cells (HEK293) were also used a source of mRNA to synthesize cDNA for PCR reactions. The HEK293 cells were found to contain message corresponding to type II, III, VI AC as well as the novel AC message. The novel AC message was also detected in human brain tissue and was most abundant in the caudate, cerebellum and hippocampus. The smallest amount of novel AC mRNA in the tested brain tissue was found in the cortex. The mRNA for the novel AC was relatively abundant in human liver.

Detection of antibodies against Borna disease virus in sera and cerebrospinal fluid of horses in the USA

Sera from 295 horses in the USA were examined by an indirect immunofluorescence assay and Western blot assays to determine the prevalence of Borna disease virus infection. Eight (2.7 per cent) of the samples were positive in both assays, and 18 (6.1 per cent) were positive only in the Western blot assay. The indirect fluorescence titres ranged from 1:20 to 1:80 of antibodies recognising the virus-specific antigen from Borna disease virus-infected cells. The purified virus-specific proteins isolated from infected rat brains were recognised by positive equine serum samples after immunostaining by a Western blot technique. Information obtained from the owners about the history of the seropositive horses revealed that they were either clinically normal or had a pathological diagnosis of disease unrelated to Borna disease. This is the first report of the detection of antibodies to Borna disease virus in horses in the USA. The disease may be more widespread in a subclinical form, with very long incubation periods, and may not necessarily be restricted to historically endemic areas.

Rabies and borna disease. A comparative pathogenetic study of two neurovirulent agents

BACKGROUND

Rabies and Borna disease viruses have been regarded as classical neurotropic agents. Many pathogenetic similarities are shared by these two negative strand RNA viruses. In view of recently gained data on the virology and pathology of these two diseases, and up-to-date comparative pathogenetic study seems to be justified.

EXPERIMENTAL DESIGN

This study is based on a survey of experimental and natural infections of laboratory animals and natural hosts. The morphologic damage to the nervous system has been evaluated by light and electron microscopy, with special emphasis on immunocytochemical methods.

RESULTS

This comparative study disclosed that both viruses are transported inside axons, pass synapses and propagate along neuronal networks. At the sites of synaptic transfer, full virus particles can never be detected in the early phase of rabies virus infection; in Borna disease virus (BDV) infection, virus particles cannot be found in any phase of disease progression. Thus, a major difference exists between the two agents insofar as rabies virus is morphologically well characterized, whereas BDV has never been visualized in tissue sections. Furthermore, rabies virus infects only neurons, whereas BDV also infects glial cells. The host range and the scale of infection of extraneural tissues by both agents is extremely similar.

CONCLUSIONS

These observations allow us to postulate that the synaptic transfer of both viruses likely ensures in the form of bare nucleocapsids (ribonucleoprotein-transcriptase complexes). While in the later phases of replication complete rabies virions are regularly assembled, BDV propagates within the central nervous system in an incomplete form, so that it remains morphologically imperceptible. Thus, BDV may appear in a complete, enveloped form only when exiting the host organism. The dissemination patterns of the two agents may be influenced by specific affinities to neurotransmitter receptor sites. It remains unresolved, why BDV readily infects non-neuronal central nervous system cells, while rabies virus remains restricted to neuronal elements.

Detection of Borna disease virus-reactive antibodies from patients with affective disorders by western immunoblot technique

Borna disease (BD) virus is a partially characterized neurotropic agent with a predilection for neurons and astrocytes in the limbic system and cerebrum of infected hosts. Although it usually causes a fatal encephalitis, some laboratory animals which have been experimentally inoculated can develop a persistent non-fatal infection characterized by a neuro-behavioral syndrome akin to human manic-depression. Using immunofluorescent techniques, we previously observed BD virus-specific antibodies in the sera of 4.5% of affectively ill patients, with the highest titers present in bipolar patients. More recently, we have developed a sensitive Western blot assay for the detection of anti-BD virus antibodies to a 38/40 kDa and 24 kDa protein in human serum. In the present study, we screened 138 affectively ill patients and 117 healthy controls and observed a significantly great proportion of patients with antibodies to the 38/40 kDa protein (P < 0.0001), the 24 kDa protein (P < 0.05) and both the 38/40 kDa and 24 kDa proteins (P < 0.025). These data extend prior reports on the presence of BD virus-specific antibodies in psychiatric patients, and suggest that a BD virus-like agent may be associated with affective illness in humans.

Delineation of putative mechanisms involved in antibody-mediated clearance of rabies virus from the central nervous system

The in vitro biological activities of several rabies virus-neutralizing monoclonal antibodies (mAbs) were compared with their ability to prevent a lethal rabies virus encephalomyelitis. The protective activity of a particular mAb in vivo did not correlate with its virus-neutralizing activity in vitro; rather it was related to the mAb's ability to inhibit virus spread from cell to cell and to restrict rabies virus RNA transcription. Since treatment of rabies virus-infected cells with virus-neutralizing mAbs results in an endocytosis of the antibody, we hypothesize that an antibody may exert its inhibitory activity even after uptake by the cell. Post-exposure treatment of rats with a mAb that inhibited both virus spread and virus RNA transcription in vitro resulted in viral clearance from the central nervous system and protected the animals against a lethal rabies virus infection.

Kinetics of virus spread and changes in levels of several cytokine mRNAs in the brain after intranasal infection of rats with Borna disease virus

We have used the reverse transcriptase-polymerase chain reaction technique to gain insight into the pathogenesis of encephalitis caused by Borna disease virus (BDV). RNA specific for BDV was first detected in the olfactory bulb of intranasally infected rats at 6 days postinfection (p.i.). At 14 days p.i., high levels of BDV RNA were found in all brain regions, and at 26 days p.i., BDV-specific RNA was also present in the eye, nasal mucosa, and facial skin. In the chronic phase of the disease, BDV RNA was identified in many peripheral organs but not in blood. Analysis of brain tissue for the presence of cytokine mRNAs revealed that the mRNA levels of interleukin-6 (IL-6), tumor necrosis factor alpha, and IL-1 alpha had increased sharply at 14 and 26 days p.i. These cytokine mRNAs reached maximum levels at the peak of inflammatory reactions and decreased drastically in the chronic phase of the disease. Although IL-2 mRNA was also found in normal brain, it was markedly increased in BDV-infected brain at 14 days p.i. Expression of gamma interferon (IFN-gamma) mRNA, which was not observed in normal rat brain, was detected at 14 days p.i. and reached a maximum level at 38 days p.i. IL-2 and IFN-gamma mRNA expression correlated with expression of CD4 and CD8 mRNAs, indicating that both CD4+ and CD8+ T lymphocytes are induced in the early stages of BDV infection. Since IFN-gamma and CD8 mRNA levels were still highly elevated in the chronic phase of Borna disease, it is likely that CD8+ T lymphocytes act to reduce inflammation and to ameliorate neurological signs during the chronic phase of infection.

Neuronal autophagy in experimental scrapie

In this study we report the formation of giant autophagic vacuoles (AV) in neurons in experimental scrapie in hamsters. Autophagy is an important step in the cellular turnover of proteins and organelles. It is known to occur in neurons under physiological as under pathological conditions. Giant AV, however, are seen very rarely only in pathological states. In our model AV are much more numerous after intracerebral (i.c.) transmission of the scrapie agent than after the transmission via the intraperitoneal route which points to a correlation between the intensity of the process and the period of incubation. As the appearance of the AV in our model is correlated chronologically with that of scrapie-associated fibrils, at least after i.c. transmission, the process may be related to a disturbance of cellular protein metabolism and, thus, to the processing of prion protein.

Technique for breast irradiation using custom blocks conforming to the chest wall contour

A technique for the treatment of the breast and regional nodes is presented. The technique involves the use of tangential fields to treat the breast and chest wall. Customized blocks which conform to the slope of the chest wall are made for each tangent field. Simulation and treatment with this technique requires no special equipment. The setup is simple and quick. A three-field technique is also described using the custom half-beam blocks; this technique avoids the use of tangential field corner blocks, thus simplifying simulation and treatment.

Learning deficiencies in Borna disease virus-infected but clinically healthy rats

Borna disease (BD) virus, a still unclassified neurotropic agent, causes either fatal encephalomyelitis or persistent asymptomatic infection in a variety of animal species. We monitored the neuronal functions of intracerebrally infected but healthy rats with three types of learning experiments. Spatial discrimination learning, using the y maze and the hole board, was significantly less successful in BD virus-infected (I) compared with mock-infected (M) rats. Similarly, I rats tended to show a certain emotional disturbance (reduced resting behavior and less anxiety) as evaluated by open-field and neophobia tests. Furthermore, in two aversive learning experiments (taste aversion and reaction suppression via Skinner box), it appeared that the I rats expressed a significantly diminished ability to learn pain avoidance compared with M rats. In conclusion, we found specific learning deficiencies together with subtle behavioral alterations suggesting that BD virus causes certain modulations of high integrative brain functions which are only detectable under experimental conditions.

Electron dose calculation using multiple-scattering theory: thin planar inhomogeneities

In this article in our series on electron dose calculation using multiple-scattering theory, we apply the Fermi-Eyges theory to the problem of a thin planar inhomogeneity present in an otherwise-layered medium. We derive expressions for the distribution function P and the location distribution L (which multiplied by the restricted mass collision stopping power is the dose directly deposited by the primary electrons) for various types of incident beams: a completely arbitrary distribution, a Gaussian point source, a pencil beam, an isotropic point source, and a broad parallel beam. We show how divergent-beam dose distributions can be determined from parallel-beam calculations, through use of equivalent configurations dependent upon the depth of dose calculation. Also, we indicate how this work can be applied to the design of wedges (or "compensators") for beam shaping to provide desired dose distributions or to match juxtaposed radiation fields. Explicit formulas for thin plates are then worked out, and we examine the appearance of hot and cold spots distal to the edge of a localized inhomogeneity, for thin half-slabs and for narrow strips. Finally, considering the case of a thin straight wedge-shaped inhomogeneity, we theoretically discover the phenomenon of a "focused hot spot" without an accompanying cold spot, and suggest the design of a "multiple-scattering lens".

Possible role of cytosolic free calcium concentrations in mediating insulin resistance of obesity and hyperinsulinemia

Insulin- and glyburide-stimulated changes in cytosolic free calcium concentrations [( Ca2+]i) were studied in gluteal adipocytes obtained from six obese women (139 +/- 3% ideal body wt) and six healthy, normal weight age- and sex-matched controls. Biopsies were performed after an overnight fast and twice (at 3 and 6 h) during an insulin infusion (40 mU/m2 per min) (euglycemic clamp). In adipocytes obtained from normal subjects before insulin infusion, insulin (10 ng/ml) increased [Ca2+]i from 146 +/- 26 nM to 391 +/- 66 nM. Similar increases were evoked by 2 microM glyburide (329 +/- 41 nM). After 3 h of insulin infusion, basal [Ca2+]i rose to 234 +/- 21 nM, but the responses to insulin and glyburide were completely abolished. In vitro insulin-stimulated 2-deoxyglucose uptake was reduced by insulin and glucose infusion (25% stimulation before infusion, 5.4% at 3 h, and 0.85% at 6 h of infusion). In obese patients, basal adipocyte [Ca2+]i was increased (203 +/- 14 nM, P less than 0.05 vs. normals). The [Ca2+]i response demonstrated resistance to insulin (230 +/- 23 nM) and glyburide (249 +/- 19 nM) stimulation. Continuous insulin infusion increased basal [Ca2+]i (244 +/- 24 nM) and there was no response to either insulin or glyburide at 3 and 6 h of study. Rat adipocytes were preincubated with 1-10 mM glucose and 10 ng/ml insulin for 24 h. Measurements of 2-deoxyglucose uptake demonstrated insulin resistance in these cells. Under these experimental conditions, increased levels of [Ca2+]i that were no longer responsive to insulin were demonstrated. Verapamil in the preincubation medium prevented the development of insulin resistance.

Relationship between cytosolic free calcium concentration and 2-deoxyglucose uptake in adipocytes isolated from 2- and 12-month-old rats

We have examined the relationship between insulin-stimulated 2-deoxyglucose uptake and cytosolic free calcium concentrations, [( Ca2+]i), in adipocytes isolated from 2- and 12-month-old rats. The basal rates of glucose uptake and the levels of cytosolic Ca2+ were only minimally reduced in 12-month-old animals. In contrast, insulin-stimulated glucose up-take and [Ca2+]i were significantly decreased in older adipocytes at all insulin concentrations (P less than 0.01). When the rate of glucose uptake was plotted as a function of [Ca2+]i, insulin-stimulated glucose uptake was almost identical in older and younger animals at any given level of [Ca2+]i. Similar to insulin, glyburide and K+ increased [Ca2+]i in both younger and older adipocytes. However, glyburide- and K+-elicited responses were lower in older rats (P less than 0.01). The effects of insulin, glyburide, and K+ on [Ca2+]i are mediated via voltage-dependent Ca2+ channels. Thus, the present observations suggest an impairment in either function and/or availability of the voltage-dependent Ca2+ channels in older animals. This was supported by the finding of reduced [3H]nitrendipine binding in adipocytes isolated from older animals (6.5% vs. 3.3% in 2- and 12-month-old rats, respectively; P less than 0.01). The results of these experiments indicate that the postreceptor changes in adipocyte responsiveness to insulin in aging may involve inadequate increases in [Ca2+]i. The latter probably occurs as a result of decreased availability and/or function of the voltage-dependent calcium channels.

The existence of an optimal range of cytosolic free calcium for insulin-stimulated glucose transport in rat adipocytes

We have examined the effects of extracellular and intracellular Ca2+ concentrations upon basal and insulin-stimulated 2-deoxyglucose uptake in isolated rat adipocytes. In the absence of extracellular Ca2+, both basal and insulin-stimulated glucose uptake were significantly reduced. Insulin-stimulated glucose transport was optimal at 1 and 2 mM Ca2+. Further increases in extracellular Ca2+ concentration (3 mM) significantly diminished insulin-stimulated glucose uptake. When intracellular Ca2+ concentrations were augmented by ionomycin (1 microM), insulin-stimulated glucose uptake was significantly reduced at extracellular Ca2+ concentrations of 2 and 3 mM. The levels of intracellular free Ca2+ concentrations were then measured with Ca2+ indicator fura-2. The correlation between the levels of intracellular free Ca2+ and the magnitude of insulin-stimulated glucose uptake revealed that the optimal effect of insulin is observed at Ca2+ levels between 140 and 370 nM. At both extremes outside of this window, both low and high levels of intracellular Ca2+ result in diminished cellular responsiveness to insulin. These data suggest that intracellular calcium concentrations may exert a dual role in the regulation of cellular sensitivity to insulin. First, there must exist a minimal concentration of intracellular calcium to promote insulin action. Second, increased levels of intracellular calcium may provide a critical signal for diminution of insulin action.

Nuclear translocation of the insulin receptor. A possible mediator of insulin's long term effects

The translocation of occupied surface insulin receptors to the nuclei of isolated hepatocytes was studied using the biologically active photosensitive insulin derivative, B2(2-nitro-4-azidophenylacetyl)-des-PheB1-insulin (NAPA-DP-insulin). When hepatocytes were photolabeled at 4 degrees C, extensively washed, and then further incubated at 37 degrees C for 1 h, photolabeled insulin receptors, which were initially localized to the cell surface, accumulated in the subsequently isolated nuclei. When the isolated nuclei were solubilized and subjected to polyacrylamide gel electrophoresis and radioautography, labeled proteins with Mr identical to the cell surface insulin receptor were detected. Light microscopic radioautography of nuclei isolated from cells incubated for 1 ha at 37 degrees C demonstrated that 28% of these nuclei were specifically labeled with one or more grains. Electron microscopic radioautography of intact cultured hepatocytes, incubated 60 min at 37 degrees C, revealed that 26% of the thin-sectioned nuclei contained at least a single grain and 8.3% of the total cell-associated associated grains were located over the nuclei. Only 1.6% of grains were localized to lysosomes. In contrast, if photolabeled hepatocytes were incubated at 4 degrees C for up to 2 h, negligible accumulation of nuclear radioactivity was observed by polyacrylamide gel electrophoresis on light or electron microscopic radioautography. Conclusions are as follows. Occupied cell surface insulin receptors can internalize and translocate to the nucleus of intact hepatocytes by a time- and temperature-dependent mechanism. Accumulation and possible degradation of insulin receptors in lysosomes involves only a small percentage of the receptors internalized. Nuclear translocation of occupied cell surface insulin receptors may be a mechanism which mediates insulin's long term effects.

Insulin and glyburide increase cytosolic free-Ca2+ concentration in isolated rat adipocytes

We investigated the effect of insulin and a hypoglycemic sulfonylurea agent glyburide on cytosolic free-Ca2+ concentrations [( Ca2+]i) in isolated rat adipocytes. Both insulin and glyburide increased [Ca2+]i in a dose-dependent manner. Half-maximal effects were seen at 0.5 ng/ml of insulin and 0.5 microM glyburide. Nifedipine (25 microM), a Ca2+-channel blocker, inhibited the effect of both agents. The effect of insulin on [Ca2+]i was 40 and 70% potentiated by ambient glucose concentrations at 180 and 300 mg/dl, respectively. Depolarizing doses of potassium (40 mM) induced an increase in cytosolic Ca2+ that was also inhibited by nifedipine. It is suggested that both insulin and glyburide increase cytosolic free Ca2+ levels at least in part by promoting Ca2+ influx through voltage-dependent Ca2+ channels.

Adaptation of Borna disease virus to the mouse

Borna disease virus has been adapted to the mouse, which required at least three passages in rat brains. Genetic specificity as studied with five inbred mouse strains was not evident. Newborn mice inoculated intracerebrally expressed antigen in neurons and remained persistently infected, with up to 10(7) infectious units per gram of brain tissue. Animals infected at different ages developed no disease and had high titres of antibodies.

The role of the glucose transport system in the postreceptor defect in insulin action associated with human aging

In an attempt to elucidate the cellular mechanisms of the insulin resistance associated with aging, insulin-mediated glucose transport was studied in isolated adipocytes obtained from 14 elderly subjects (mean age +/- SE, 69 +/- 2 yr) and 11 nonelderly (40 +/- 4 yr) subjects using the nonmetabolized glucose analogue 3-O-methylglucose. In elderly subjects with normal oral glucose tolerance tests, maximal insulin-stimulated glucose transport was reduced compared to nonelderly control levels [1.26 +/- 0.17 (+/- SE) vs. 1.96 +/- 0.26 pmol/2 X 10(5) cells X 15 sec; P less than 0.025). Elderly subjects with nondiagnostic oral glucose tolerance tests had more marked reductions in basal, submaximal, and maximal stimulated rates of glucose transport compared to the nonelderly group. The elderly group with the greatest decrease in in vitro glucose transport also had the greatest decrease in in vivo insulin-stimulated glucose disposal, whereas the elderly subjects with the mildest in vitro defect also had the smallest reduction in in vivo glucose disposal. A significant positive relationship existed between the maximal rate of in vitro glucose transport and the maximal rate of in vivo glucose disposal in the various subjects (Spearman rank correlation coefficient = 0.54; P less than 0.05). We conclude that aging is associated with a significant defect in the glucose transport system in isolated adipocytes, which may account for the post-receptor defect in in vivo insulin action in aging.

Characterization of the receptor binding properties of monoiodoinsulin isomers and the identification of different insulin receptor specificities in hepatic and extrahepatic tissues

Insulin was iodinated with 125I using a modification of the lactoperoxidase method. This iodinated insulin mixture was then separated by HPLC, allowing studies to be performed on the pure monoiodoinsulin isomers labeled at the tyrosyl residuesat A14, B16, or B26.

Binding studies in adipocytes revealed the relative affinity for these isomers to be 1.00:0.99:1.30 (A14, B16, and B26, respectively). The increase in binding affinity was shown to be due to a slower dissociation rate rather than an accelerated association rate. Receptor mediated internalization of the different iodinated isomers was assessed and these results showed that the isomers were internalized and degraded in proportion to their relative binding affinities. The biologic activity of the B26 isomer to stimulate adipocyte glucose oxidation was measured and showed that the B26 isomer had 30% greater biologic potency compared with native insulin, consistent with its 30% increase in binding potency. Thus, the B26 monoiodoinsulin isomer behaves as a superagonist.

Binding studies using extrahepatic tissue (i.e., adipocytes, cultured human fibroblasts, IM-9 lymphocytes, and human placental membranes) consistently revealed that the relative binding affinity for the B26 isomer was always greater than the A14 isomer (1.29, 2.11,1.22, and 1.35, respectively) while the binding affinity of the B16 isomer was generally comparable to the A14 isomer. In hepatic tissue (whole cell, liver plasma membranes, and partially purified, solubilized liver receptors) binding studies illustrated that the B26 isomer consistently had a lower relative affinity when compared to the A14 isomer (0.75 : 0.69 : 0.77).

In conclusion, (1) the B26 monoiodoinsulin isomer exhibits higher binding affinity and greater biologic activity in adipocytes than native insulin, and (2) the B26 monoiodoinsulin isomer has a higher binding affinity in extrahepatic tissues but exhibits a lower binding affinity in hepatic tissues when compared with the A14 monoiodoinsulin isomer, indicating a striking difference in functional specificity between the hepatic and the extrahepatic insulin receptor.

Persistent, tolerant or subacute infection in Borna disease virus-infected rats

The rabbit-adapted Borna disease (BD) virus strain V was passaged by intracerebral infection of 1-day-old Wistar rats. Infectivity titres reached 10(8) infectious units per gram of brain 4 weeks after infection. No clinical signs were evident. The persistent infection could be induced with adapted or field strains of BD virus. Strains were identified by neutralization tests. The virulence of the rabbit-adapted BD virus for the rat increased with rat passages. The 5th passage induced clinical symptoms in animals infected at 1 week of age or older. Between 20% and 50% of diseased rats died. Virus-specific antigen was detectable immunohistologically in neurons of rats infected at all ages. Animals inoculated at 1 or 2 months of age, but not the neonatal rats, showed signs of inflammation in the brain. Infected rats produced specific antibodies. In the older groups (infected at ages of 1 or 2 months), and especially in surviving animals, occasionally, neutralizing antibodies with high titres were found. Transfer of primed spleen cells resulted in subacute disease. These findings demonstrate that neonatal rats can acquire a persistent, tolerant infection and that expression of disease is mediated by immunological factors.

Insulin binding to erythrocytes incubated in vitro at physiological temperature

We have investigated the previously described time-dependent increase in specific insulin binding to freshly isolated human erythrocytes incubated at 37 C. We found that at 37 C, specific insulin binding to erythrocytes rose to and remained at equilibrium for the first 90 min of incubation; thereafter, it rose in a rapid linear fashion, directly related to the increase in the degradation of unbound insulin and paralleling the intensity of visible hemolysis. The rise in specific binding was intensified by conditions in which hemolysis was enhanced and attenuated by conditions designed to limit hemolysis or by agents capable of inhibiting the degradation of insulin despite hemolysis. Thus, gentle handling of the cells prevents hemolysis, the degradation of insulin, and the increase in apparent insulin binding. Furthermore, 5% albumin, 2.5 mM N-ethylmaleimide, or excess unlabeled insulin (100 micrograms/ml) inhibited insulin degradation (even in the presence of hemolysis) and prevented the rise in insulin binding. The rise in cell-associated radioactivity after 90 min of incubation at 37 C was due to cellular uptake of products of insulin degradation, since degraded [125I]insulin rapidly associated with freshly prepared erythrocytes. Acid extraction studies suggested that about 60% of the cell-associated degraded material was intracellular, while the remaining approximately 40% was bound to the cell surface. The data suggest that the rise in binding in erythrocytes incubated at 37 C is a result of insulin degradation products which associate with the cells. The generation of degraded insulin is due to hemolysate released from leaky cells, and this phenomenon is unique to the in vitro situation.