The landscape of genomic structural variation in Indigenous Australians

Indigenous Australians harbour rich and unique genomic diversity. However, Aboriginal and Torres Strait Islander ancestries are historically under-represented in genomics research and almost completely missing from reference datasets1-3. Addressing this representation gap is critical, both to advance our understanding of global human genomic diversity and as a prerequisite for ensuring equitable outcomes in genomic medicine. Here we apply population-scale whole-genome long-read sequencing4 to profile genomic structural variation across four remote Indigenous communities. We uncover an abundance of large insertion-deletion variants (20-49 bp; n = 136,797), structural variants (50  b-50 kb; n = 159,912) and regions of variable copy number (>50 kb; n = 156). The majority of variants are composed of tandem repeat or interspersed mobile element sequences (up to 90%) and have not been previously annotated (up to 62%). A large fraction of structural variants appear to be exclusive to Indigenous Australians (12% lower-bound estimate) and most of these are found in only a single community, underscoring the need for broad and deep sampling to achieve a comprehensive catalogue of genomic structural variation across the Australian continent. Finally, we explore short tandem repeats throughout the genome to characterize allelic diversity at 50 known disease loci5, uncover hundreds of novel repeat expansion sites within protein-coding genes, and identify unique patterns of diversity and constraint among short tandem repeat sequences. Our study sheds new light on the dimensions and dynamics of genomic structural variation within and beyond Australia.

Indigenous Australian genomes show deep structure and rich novel variation

The Indigenous peoples of Australia have a rich linguistic and cultural history. How this relates to genetic diversity remains largely unknown because of their limited engagement with genomic studies. Here we analyse the genomes of 159 individuals from four remote Indigenous communities, including people who speak a language (Tiwi) not from the most widespread family (Pama-Nyungan). This large collection of Indigenous Australian genomes was made possible by careful community engagement and consultation. We observe exceptionally strong population structure across Australia, driven by divergence times between communities of 26,000-35,000 years ago and long-term low but stable effective population sizes. This demographic history, including early divergence from Papua New Guinean (47,000 years ago) and Eurasian groups1, has generated the highest proportion of previously undescribed genetic variation seen outside Africa and the most extended homozygosity compared with global samples. A substantial proportion of this variation is not observed in global reference panels or clinical datasets, and variation with predicted functional consequence is more likely to be homozygous than in other populations, with consequent implications for medical genomics2. Our results show that Indigenous Australians are not a single homogeneous genetic group and their genetic relationship with the peoples of New Guinea is not uniform. These patterns imply that the full breadth of Indigenous Australian genetic diversity remains uncharacterized, potentially limiting genomic medicine and equitable healthcare for Indigenous Australians.

More than dirt: Sedimentary ancient DNA and Indigenous Australia

The rise of sedimentary ancient DNA (sedaDNA) studies has opened new possibilities for studying past environments. This groundbreaking area of genomics uses sediments to identify organisms, even in cases where macroscopic remains no longer exist. Managing this substrate in Indigenous Australian contexts, however, requires special considerations. Sediments and soils are often considered as waste by-products during archaeological and paleontological excavations and are not typically regulated by the same ethics guidelines utilised in mainstream 'western' research paradigms. Nevertheless, the product of sedaDNA work-genetic information from past fauna, flora, microbial communities and human ancestors-is likely to be of cultural significance and value for Indigenous peoples. This article offers an opinion on the responsibilities of researchers in Australia who engage in research related to this emerging field, particularly when it involves Indigenous communities. One aspect that deserves consideration in such research is the concept of benefit sharing. Benefit sharing refers to the practice of ensuring that the benefits that arise from research are shared equitably with the communities from which the research data were derived. This practice is particularly relevant in research that involves Indigenous communities, who may have unique cultural and spiritual connections to the research material. We argue that the integration of Traditional Knowledges into sedaDNA research would add enormous value to research and its outcomes by providing genomic outputs alongside and within the rich context of multimillennia oral histories.

Persisting chemosensory dysfunction in COVID-19 - a cross-sectional population-based survey

BACKGROUND

Chemosensory dysfunction (CD) has been reported as a common symptom of SARS-CoV-2 infection, but it is not well understood whether and for how long changes of smell, taste and chemesthesis persist in infected individuals.

METHODOLOGY

Unselected adult residents of the German federal state of Schleswig-Holstein with Polymerase Chain Reaction (PCR)-test-confirmed SARS-CoV-2 infection were invited to participate in this large cross-sectional study. Data on the medical history and subjective chemosensory function of participants were obtained through questionnaires and visual analogue scales (VAS). Olfactory function (OF) was objectified with the Sniffin Sticks test (SST), including threshold (T), discrimination (D) and identification (I) test as well as summarized TDI score, and compared to that in healthy controls. Gustatory function (GF) was evaluated with the suprathreshold taste strips (TS) test, and trigeminal function was tested with an ampoule containing ammonia.

RESULTS

Between November 2020 and June 2021, 667 infected individuals (mean age: 48.2 years) were examined 9.1 months, on average, after positive PCR testing. Of these, 45.6% had persisting subjective olfactory dysfunction (OD), 36.2% had subjective gustatory dysfunction (GD). Tested OD, tested GD and impaired trigeminal function were observed in 34.6%, 7.3% and 1.8% of participants, respectively. The mean TDI score of participants was significantly lower compared to healthy subjects. Significant associations were observed between subjective OD and GD, and between tested OD and GD.

CONCLUSION

Nine months after SARS-CoV-2 infection, OD prevalence is significantly increased among infected members of the general population. Therefore, OD should be included in the list of symptoms collectively defining Long-COVID.

Beyond platitudes: a qualitative study of Australian Aboriginal people's perspectives on biobanking

BACKGROUND

Biobanks are vital resources for genetics and genomics, and it is broadly recognised that for maximal benefit it is essential that they include samples and data from diverse ancestral groups. The inclusion of First Nations people, in particular, is important to prevent biobanking research from exacerbating existing health inequities, and to ensure that these communities share in the benefits arising from research.

AIMS

To explore the perspectives of Australian Aboriginal people whose tissue - or that of their family members - has been stored in the biobank of the National Centre for Indigenous Genomics (NCIG).

METHODS

Semi-structured interviews with 42 Aboriginal people from the Titjikala, Galiwinku, Tiwi Islands, Yarrabah, Fitzroy Crossing, Derby, One Arm Point and Mulan communities, as well as a formal discussion with A. Hermes, an Indigenous Community Engagement Coordinator at the NCIG who had conducted the interviews. The interviews and the structured discussion were double coded using a procedure informed by Charmaz's outline of grounded theory analysis and Morse's outline of the cognitive basis of qualitative research.

RESULTS

In this article, we report on A. Hermes' interviews with members from the above Aboriginal communities, as well as on her personal views, experiences, and interpretations of the interviews she conducted with other community members. We found that participation in the NCIG biobank raised issues around broken trust, grief and loss, but also - somewhat unexpectedly - was perceived as a source of empowerment, hope and reconnection.

CONCLUSIONS

This research reminds us (again) of the need to engage deeply with communities in order to respond appropriately with respect for their cultural values and norms, and to develop culturally relevant policies and processes that enhance the benefits of biobank participation and minimise potential harms.

Barriers and Considerations for Diagnosing Rare Diseases in Indigenous Populations

Advances in omics and specifically genomic technologies are increasingly transforming rare disease diagnosis. However, the benefits of these advances are disproportionately experienced within and between populations, with Indigenous populations frequently experiencing diagnostic and therapeutic inequities. The International Rare Disease Research Consortium (IRDiRC) multi-stakeholder partnership has been advancing toward the vision of all people living with a rare disease receiving an accurate diagnosis, care, and available therapy within 1 year of coming to medical attention. In order to further progress toward this vision, IRDiRC has created a taskforce to explore the access barriers to diagnosis of rare genetic diseases faced by Indigenous peoples, with a view of developing recommendations to overcome them. Herein, we provide an overview of the state of play of current barriers and considerations identified by the taskforce, to further stimulate awareness of these issues and the passage toward solutions. We focus on analyzing barriers to accessing genetic services, participating in genomic research, and other aspects such as concerns about data sharing, the handling of biospecimens, and the importance of capacity building.

Equitable Expanded Carrier Screening Needs Indigenous Clinical and Population Genomic Data

Expanded carrier screening (ECS) for recessive monogenic diseases requires prior knowledge of genomic variation, including DNA variants that cause disease. The composition of pathogenic variants differs greatly among human populations, but historically, research about monogenic diseases has focused mainly on people with European ancestry. By comparison, less is known about pathogenic DNA variants in people from other parts of the world. Consequently, inclusion of currently underrepresented Indigenous and other minority population groups in genomic research is essential to enable equitable outcomes in ECS and other areas of genomic medicine. Here, we discuss this issue in relation to the implementation of ECS in Australia, which is currently being evaluated as part of the national Government's Genomics Health Futures Mission. We argue that significant effort is required to build an evidence base and genomic reference data so that ECS can bring significant clinical benefit for many Aboriginal and/or Torres Strait Islander Australians. These efforts are essential steps to achieving the Australian Government's objectives and its commitment "to leveraging the benefits of genomics in the health system for all Australians." They require culturally safe, community-led research and community involvement embedded within national health and medical genomics programs to ensure that new knowledge is integrated into medicine and health services in ways that address the specific and articulated cultural and health needs of Indigenous people. Until this occurs, people who do not have European ancestry are at risk of being, in relative terms, further disadvantaged.

Meta-analysis of the safety, tolerability, and efficacy of lopinavir/ritonavir-containing antiretroviral therapy in HIV-1-infected women

PURPOSE

Women comprise ≯50% of HIV-infected patients, yet safety, tolerability, and efficacy data in women taking antiretrovirals (ARVs) are limited. Lopinavir/ ritonavir (LPV/r)-anchored regimens are globally the most widely prescribed HIV-1 protease inhibitor regimens. The objective was to investigate the safety and efficacy of LPV/r-based therapy in women.

METHODS

A database query yielded all available data in HIV-1-infected subjects receiving LPV/r-based triple-ARV regimens from randomized clinical trials lasting ≥48 weeks from Abbott or Abbott-supported AIDS Clinical Trials Group studies. Efficacy (HIV-1 RNA levels, CD4+ T-cell counts) and safety and tolerability (treatment discontinuation, treatment-related adverse events [AE], and clinical laboratory abnormalities) at 48 weeks were assessed for total women, women by age (≥50, <50 years) and body mass index (BMI; <25, ≥25 to <30, ≥30 kg/m2), and sex.

RESULTS

Nine hundred ninety-two women initiated LPV/r-based therapy (of whom 79.2% were ARV-naïve), with 83.6% completing 48 weeks of treatment. There were 75.5% of women who achieved a threshold of HIV RNA <400 copies/mL by intent-to-treat, non-completer equals failure (ITT, NC = F) analysis, with a mean ± SE CD4+ T-cell count increase of 191.6 ± 4.92 cells/mm3 from baseline. Women aged ≥50 versus <50 years had higher incidence of moderate-to-severe treatment-related AEs and certain laboratory abnormalities, better virologic response (HIV RNA <400 copies/mL by ITT, NC = F), similar immunologic responses, and similar overall incidence of treatment discontinuations. Higher incidences of certain moderate-to-severe treatment-related AEs and laboratory abnormalities occurred in women with BMI ≥30 kg/m2; however, no effect of BMI on efficacy or discontinuation was observed.

CONCLUSIONS

LPV/r-based regimens were efficacious and well-tolerated in women without marked differences based on age and BMI categories evaluated.

[Extrapulmonary small-cell lung cancer]

We report on a 61-year-old male patient who was admitted due to dysphagia, hoarseness and stridor. CT showed extensive metastasis to the thyroid and left adrenal gland. Histology revealed small-cell lung cancer. A primary tumour could not be detected in the lungs and mediastinum. Good symptom control could be achieved by administration of platinum-based chemotherapy.

[Non-small-cell carcinoma of the lung with invasive Aspergillus infection after chemotherapy]

HISTORY

A 56-year-old woman had two years previously undergone a neck dissection and subsequent adjuvant radiotherapy for an adenocarcinoma at the base of the tongue (pT2NOMOG2) when a percutaneous endoscopic gastrostomy (PEG) catheter had been placed. She was now admitted for chemotherapy, recent onset of severe pain in the left hip and knee having been caused by metastasis of a non-small-cell lung carcinoma (NSCLC). She was cachectic and in a reduced general condition (Karnofsky index 80), but had recently only occasionally used the PEG catheter. There were no inflammatory changes of the skin at the site of the PEG.

TREATMENT, COURSE AND OUTCOME

The first chemotherapy cycle was initially without complication, but after a week the patient's general condition deteriorated and she developed nausea, fever and pain around the markedly inflamed site of the PEG catheter insertion. Laboratory tests indicated severe neutropenia. Intensive antibiotic and antimycotic treatment at first brought about some improvement, but she died 11 days after admission. Necropsy revealed invasive aspergillosis, with the PEG as the portal of entry and spreading to the stomach and intestines, where numerous hyphae were identified. There had also been a disseminated intravascular coagulopathy.

CONCLUSION

Bacterial infections (and occasionally, but difficult to diagnose, fungal infection) are quite common as a result of neutropenia during chemotherapy of solid tumors. Various risk factors, including reduced general condition and weight loss, must be individually assessed in the prevention or treatment of associated infectious complications in such cases.

[Analysis of treatment outcomes in two patient cohorts (2004-2005 and 2007-2008) with limited and extensive disease small-cell lung cancer]

PURPOSE

The aim of this retrospective study was to compare patient characteristics, treatment patterns and treatment results in two groups of patients with limited disease (LD) and extensive disease (ED) small-cell lung cancer (SCLC) in 2004 - 2005 vs. 2007 - 2008.

PATIENTS AND METHODS

We included all patients with LD or ED SCLC in this retrospective analysis who were diagnosed in our department in the periods 2004 - 2005 and 2007 - 2008. We collected data on patient characteristics, chemotherapy, radiotherapy, treatment response and median survival. Statistical analyses were separately performed for patients in LD and ED SCLC.

RESULTS

109 patients had LD SCLC. The response rate on first-line therapy was 74 %. More than half of the cases had recurrent disease. Second-line treatment was given to about two thirds of these patients. Third-line therapy was administered in around 15 % of all cases. Prophylactic cranial irradiation was performed more frequently from 2007 - 2008. The median survival was 17 months. There were no statistically significant differences regarding patient characteristics and treatment results. ED SCLC was present in 188 patients. The response rate was around 68 %. All patients relapsed, second-line therapy was administered in half of these cases; third-line therapy in 10 % of all cases. No statistically significant differences were detected between the two time frames. Median survival was 10 months.

CONCLUSION

Overall, no statistically significant differences were present for patients with LD and ED SCLC in 2004 - 2005 vs. 2007 - 2008. Prophylactic cranial irradiation was employed more frequently in LD SCLC from 2007.

[Late recurrence of renal cell carcinoma in a solitary enlarged paratracheal lymph node]

We report on a 67-year-old male patient who had undergone treatment for renal cell carcinoma 19 years previously. A CT scan showed a solitary enlarged lymph node in the right upper paratracheal region. A specimen was obtained by endobronchial ultrasound with transbronchial needle aspiration. Cytological analysis revealed lymph node metastasis of the late relapsing renal cell carcinoma.

Baseline anxiety effect on outcome of SSRI treatment in patients with severe depression: escitalopram vs paroxetine

OBJECTIVE

To investigate if treatment outcome for severely depressed patients depends on their baseline level of anxiety.

RESEARCH DESIGN AND METHODS

Patients with a primary diagnosis of severe major depressive disorder (n = 459) were randomised to 24 weeks of double-blind treatment with escitalopram (20 mg) or paroxetine (40 mg). Post hoc analyses of efficacy in patients with a baseline HAM-A total score < or =20 (n = 171) or >20 (n = 280) were based on analysis of covariance (ANCOVA) (ITT, LOCF).

RESULTS

At week 24, the mean change from baseline in MADRS total scores was -24.2 for escitalopram-treated patients (n = 141) and -21.5 for paroxetine-treated patients (n = 139) (p < 0.05) in high baseline anxiety patients and the mean change from baseline in HAM-A total score was -17.4 (escitalopram) and -15.1 (paroxetine) (p < 0.05). When examining the proportion of complete remitters (CGI-S = 1) after 24 weeks of treatment, there was an increasing treatment difference as a function of baseline HAM-A total score in favour of escitalopram (ITT, LOCF). There was no treatment difference in the low baseline anxiety group. Significantly more patients (p < 0.01) withdrew from the paroxetine group (31%) than from the escitalopram group (17%), partly as the result of significantly more withdrawals due to AEs (p < 0.05). Incidence of AEs and withdrawals were not related to baseline anxiety and there were no significant differences in the incidence of individual AEs with escitalopram compared to paroxetine.

LIMITATIONS

The post hoc nature of these analyses, the absence of placebo control group, and the requirement that patients should be suffering from severe depression, limit the generalisability of the results.

CONCLUSION

Patients with severe depression together with comorbid anxiety symptoms responded significantly better to treatment with escitalopram 20 mg compared with paroxetine 40 mg. Contrary to paroxetine, escitalopram maintained its efficacy with increasing baseline anxiety levels.

Lopinavir protein binding in HIV-1-infected pregnant women

BACKGROUND

Pregnancy may alter protein binding (PB) of highly bound protease inhibitors due to changes in plasma concentrations of albumin and alpha-1 acid glycoprotein (AAG). Small changes in PB can greatly impact the fraction of drug unbound (FU) exerting pharmacological effect. We report lopinavir (LPV) PB during third trimester (antepartum, AP) compared to > or =1.7 weeks postpartum (PP) to determine if FU changes compensate for reduced total concentrations reported previously.

METHODS

P1026s enrolled women receiving LPV/ritonavir, soft gel capsules 400/100 mg or 533/133 mg twice daily. LPV FU, albumin and AAG were determined AP and PP.

RESULTS

AP/PP samples were available from 29/25 women respectively with all but one woman receiving the same dose AP/PP. LPV FU was increased 18% AP vs. PP (mean 0.96+/-0.16% AP vs. 0.82+/-0.21% PP, P=0.001). Mean protein concentrations were reduced AP (AAG=477 mg/L; albumin=3.28 mg/dL) vs. PP (AAG=1007 mg/L; albumin=3.85 mg/dL) (P<0.0001 for each comparison). AAG concentration correlated with LPV binding. Total LPV concentration did not correlate with LPV FU AP or PP. However, higher LPV concentration PP was associated with reduced PB and higher FU after adjustment for AAG.

CONCLUSIONS

LPV FU was higher and AAG lower AP vs. PP. The 18% increase in LPV FU AP is smaller than the reduction in total LPV concentration reported previously and is not of sufficient magnitude to eliminate the need for an increased dose during pregnancy.

[Consecutive aspiration]

We report on a 40 year-old man who presented with recurrent pneumonia with limited effect of antibiotics. A chest CT-scan revealed a tumor in the right hilar region leading to a partial atelectasis of the middle lobe. We removed a rather uncommon foreign body from the right main stem bronchus.

Efficacy of interferon plus ribavirin in the treatment of hepatitis C virus genotype 5

Hepatitis C virus (HCV) genotype 5 has only been reported in a few countries and treatment response has not been well characterized. Our aim is to present the treatment outcome for HCV genotype 5 patients evaluated at three medical centres in Syria between January 2004 and June 2007. Medical records were reviewed retrospectively. Treatment consisted of ribavirin 1 000-1 200 mg daily plus interferon alpha-2a, 3 MU x 3/week or pegylated-interferon alpha-2a, 180 mug/week. Patients were treated for 24 or 48 weeks. Sustained viral response (SVR) was assessed at the end of a 6-month follow-up period. Twenty-six treatment-naïve patients with HCV genotype 5 have completed the course of anti-HCV therapy and a 6-month follow-up. An SVR was achieved in 54% (47% with standard interferon and 67% with pegylated interferon, P = 0.43). A trend towards better results was observed for younger patients, low viremia and mild fibrosis. SVR was similar for treatment course of 24 or 48 weeks. In summary, treatment of HCV genotype 5 with combination therapy resulted in SVR in 54% of patients. Twenty-four weeks of treatment might be adequate. Further research should evaluate the ideal duration of treatment.

A randomized phase III trial of irinotecan plus carboplatin versus etoposide plus carboplatin in patients with small cell lung cancer, extensive disease (SCLC-ED): IRIS-Study

7523

Background: A Japanese randomized trial has shown superior survival for SCLC-ED patients receiving irinotecan+cisplatin as compared to etoposide+cisplatin. Our trial was performed to evaluate the effect of irinotecan+carboplatin compared to oral etoposide+carboplatin. Patients and Methods: In a phase III trial, patients with SCLC-ED were randomly assigned to receive carboplatin, AUC=4 (Chatelut formula) and irinotecan, 175 mg/m2, both on day 1 (IC) or carboplatin (Chatelut AUC=4) on day 1 and etoposide 120 mg/m2/day, orally, on days 1–5 (EC). In both arms, courses were repeated on day 21 with 4 cycles planned. Primary endpoint was overall survival (OS), secondary endpoints were quality of life, evaluated by EORTC-QLQ-C30 and QLQ-LC 13, and complete response rate. There were neither upper limits for age or performance status. Results: Between November, 2001 and July, 2005, 220 patients were randomized. 210 patients were eligible for analysis (other type of cancer, 8 pts., limited disease, 1 pt., elevated liver function tests, 1 pt.). Performance status (PS) 0: 20 patients, PS 1: 91, PS 2: 62, PS 3: 29, PS 4: 8. Median age IC was 67 years (46–81), EC 67 years (39–82). OS was 255 days (IC) versus 214 days (EC) (P=0.04, log rank test). HR for overall survival was 1.34, 95% CI: 1.01–1.79. 1-year survival was 35% vs 28%. CR was observed in 18 patients in the IC arm and 7 patients in the EC arm (P=0.02, chi-square test). There were no statistically significant differences with respect to haematological grade III-IV toxicity. No severe diarrhea was observed in the IC group. There were no significant differences regarding quality of life. Conclusion: Irinotecan + carboplatin is superior to oral etoposide + carboplatin with respect to overall survival in SCLC-ED.

No significant financial relationships to disclose.

Allergoid-specific T-cell reaction as a measure of the immunological response to specific immunotherapy (SIT) with a Th1-adjuvanted allergy vaccine

BACKGROUND

Specific immunotherapy (SIT) is believed to modulate CD4+ T-helper cells. In order to improve safety, SIT vaccines are often formulated with allergoids (chemically modified allergens). Interaction between T-cells and allergoids is necessary to influence cellular cytokine expression. There have been few reports on identification the early cellular effects of SIT.

METHOD

Patients allergic to grass and/or mugwort pollen (n= 21) were treated with a 4-shot allergy vaccine (Pollinex Quattro) containing appropriate allergoids (grass/rye and/or mugwort) adsorbed to L-tyrosine plus a Th1 adjuvant, monophosphoryl lipid A (MPL). Fourteen grass-allergic patients served as untreated controls. Using the peripheral blood mononuclear cells of these patients, an optimized lymphocyte transformation test (LTT) was employed to monitor the in vitro proliferative response of T-cells to an allergoid challenge (solubilised Pollinex Quattro) before the first and last injection and then 2 and 20 weeks after the final injection. Control challenges utilised preparations of a similar pollen vaccine without the adjuvant MPL and a tree pollen vaccine with and without MPL.

RESULTS

The LTT showed increased LTT stimulation indices (SI) in 17/20 SIT patients when the solublised vaccine preparation was used as a challenge before the last injection and 2 weeks after, in comparison to pre-treatment levels. Twenty weeks after therapy, the SI decreased to baseline level. A vaccine challenge without MPL gave lower SI levels. A challenge of a clinically inappropriate tree allergoid vaccine gave no response, and a nontreated group also showed no response.

CONCLUSION

Following a short-course SIT adjuvated with MPL, challenges of allergoids were shown to activate allergen-specific T cells in vitro. There was an additional stimulating effect when the challenge was in combination with MPL. There were no non-specific effects of MPL, shown by the tree allergoid/MPL control. The timing of the response was closely correlated to the treatment course; reactivity fell two weeks after the final injection and 20 weeks later it was at baseline level. Thus an immunological response to SIT was detected after very few injections. This methodology could provide a basis for monitoring the immediate progress of allergy vaccinations.

Evolution of microcirculatory disturbances after permanent middle cerebral artery occlusion in rats

Nonischemic brain capillaries show a continuous and heterogeneous plasma perfusion. In the current study, plasma perfusion was investigated in rats during 2 to 168 hours of permanent middle cerebral artery occlusion. Perfused capillaries were detected in brain cryosections by fluorescein isothiocyanate (FITC) dextran after 10 minutes of circulation time. Heterogeneity of capillary perfusion was identified by Evans blue (EB), which circulated for 3 seconds. In this setting, the heterogeneity of intracapillary EB concentrations reflects heterogeneities in capillary flow velocities. The CBF was quantified by simultaneous iodo[14C]antipyrine autoradiography. When moving from normal flow to low-flow areas in the ischemic hemisphere, three states of capillary filling could be distinguished: state 1--fast perfusion, filling by FITC dextran and EB (CBF 0.33 mL x g(-1) x min(-1)); state 2--delayed perfusion, only FITC dextran filling (CBF 0.104 mL x g(-1) x min(-1)); state 3--minimal perfusion, no dye filling (CBF 0.056 mL x g(-1) x min(-1)). In tissue of state 1 at the borderline to ischemic tissue, a higher heterogeneity of intracapillary EB concentration (85.7%) was found than in the contralateral nonischemic hemisphere (76.4%) (P < 0.05), indicating a compromised microcirculation. The adjacent ischemic areas were filled by FITC dextran (state 2) 2 to 4 hours after middle cerebral artery occlusion, indicating a maintained, although slow, perfusion at this time. Later, minimal perfused areas (state 3) progressively replaced the delayed perfused areas (state 2). This study shows, for the first time, the evolution of microvascular disturbances in relation to CBF. In the low-flow areas, an early residual plasma perfusion is later followed by a lack of perfusion or minimal perfusion. In areas of higher, although reduced flow at the border between normal and ischemic tissue, an extreme capillary perfusion heterogeneity indicates permanent microcirculatory abnormalities.

Novel mutations in the thiazide-sensitive NaCl cotransporter gene in patients with Gitelman syndrome with predominant localization to the C-terminal domain

Gitelman syndrome (familial hypokalemia-hypomagnesemia syndrome) is an autosomal recessive inherited renal disorder characterized by defective tubular reabsorption of magnesium and potassium. In this study a group of 18 unrelated and 2 related Gitelman patients, collected from six different countries have been screened for mutations in the human thiazide-sensitive sodium-chloride cotransporter (SLC12A3) gene. Fourteen novel SLC12A3 mutations are presented along with six mutations described earlier, and three neutral polymorphisms. Among the tested patients are two who carry a total of three heterozygous SLC12A3 mutations. Two-thirds of the total number of mutant SLC12A3 alleles are amino acid substitutions. Most SLC12A3 gene mutations, 14 out of a total of 20, are localized at the intracellular carboxy-terminal domain of the NCCT protein. The pathogenicity of individual SLC12A3 mutations is based upon their predicted effect on SLC12A3 protein, and segregation in family members. Evolutionary conservation of substituted amino acid residues and their frequency in control chromosomes is presented. Identical mutations have been found in Gitelman families from different geographical origin, suggesting ancient mutations originating from a common ancestor. As yet, we have not found any evidence for a possible genotype-phenotype correlation.