Long-term effects of coronavirus disease 2019 on the cardiovascular system: the CV COVID-19 registry

Background

Patients with COVID-19 have an increased risk of cardiovascular adverse events during the acute phase. However, the long-term cardiovascular outcomes are unknown.

Objective

We aimed to determine the long-term effects of COVID-19 in the cardiovascular system.

Methods

This is a multicenter, observational, retrospective registry conducted at 17 centers in Spain and Italy. Consecutive patients older than 18 years who underwent a real-time reverse transcriptase-polymerase chain reaction (RT-PCR) for SARS-CoV2 in the participating institutions were included. Patients were classified into two groups, according to the results of the RT-PCR: COVID-19 positive or negative. The primary outcome was cardiovascular (CV) death at 1-year. The secondary outcomes included acute myocardial infarction, stroke, heart failure hospitalization, pulmonary embolism, and serious cardiac arrhythmias at 1-year. Outcomes were compared between the two groups. An independent clinical event committee adjudicated events.

Results

A total of 4427 patients were included, 3578 (80.8%) patients with COVID-19 and 849 (19.2%) without COVID-19. COVID-19 patients were older, had a higher rate of classical cardiovascular risk factors, except for active smoking, and had fewer comorbidities. At a median time of 13.5 (IQR 11.8–15.8) months, after an adjustment by baseline characteristics, there was no difference in CV death (1.4% vs. 1.1%; HR 1.03 [0.49–2.18]; p=0.941) between patients with COVID-19 and without. However, COVID-19 patients experienced higher rate of venous thromboembolism (VTE) (3.9% vs. 0.6%, HR 6.11 [2.46–15.16]; p=0.001), major bleeding (2.9% vs. 0.5%, HR 5.38 [1.95–14.84]; p=0.001), and serious cardiac arrhythmias (2.6% vs. 0.9%, HR 2.25 [1.07–4.73]; p=0.033). During follow-up, between discharge and end of follow-up, COVID-19 patients did not experience a higher risk of adverse cardiovascular outcomes (composite of CV death, any MI, ischemic stroke, systemic arterial thrombosis, VTE, heart failure hospitalization, or any serious arrhythmia) compared to patients without (HR 0.80; [0.53–1.21]; p=0.298).

Conclusions

At 1-year follow-up, COVID-19 was not associated with an increased risk of cardiovascular death but with a higher risk of VTE events, major bleeding, and serious cardiac arrhythmias. COVID-19 was not associated with a higher risk of adverse cardiovascular events during follow-up.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Carlos III Institute, Madrid, Spain

Abstract 641: Systems biology identifies Gleevec as a specific inhibitor of CLIP-170S, a novel +TIP isoform, which causes taxane resistance in cancer cells and patients by obstructing the Microtubule pore

Taxanes are widely used in the treatment of solid tumor patients including gastric cancer (GC). Post-hoc analysis of the clinical trial that led to docetaxel approval in GC, revealed that patients with diffuse histological subtype were intrinsically resistant to taxanes. As yet, the molecular basis of clinical drug resistance remains poorly elucidated. Using a panel of GC cell lines, we identified a subset with intrinsic taxane resistance due to impaired drug-target engagement, in the absence of tubulin mutations or decreased drug accumulation. We discovered a novel, short variant of the microtubule (MT) +TIP binding protein CLIP-170, hereafter CLIP-170S, which was preferentially expressed in resistant cells. Mass-spec proteomics and 5'RACE showed that CLIP-170S lacked the first 150 amino acids, thus, missing the Cap-Gly domain required for +TIP localization. Microscopy of endogenous or exogenous proteins revealed that CLIP-170S was mislocalized from +TIP to the MT lattice in contrast to the canonical CLIP-170. Stable CLIP-170S knock down (KD) entirely reversed taxane-resistance (300 fold), directly establishing CLIP-170S as the cause of taxane resistance.

Quantitation of Flutax-2 (fluorescently labeled taxane) binding kinetics by live-cell imaging of native cytoskeletons in sensitive and resistant cells, showed that Flutax-2 dissociated faster from MTs in CLIP-170S-expressing resistant cells due to slower association rate. CLIP-170S-KD fully restored Flutax-2 binding to MTs, indicating that CLIP-170S impedes taxane-MT interaction. As taxane binding to MT lumen requires entry via the MT pore, we used chemical probes binding at the outer-only (hexaflutax) or luminal (cyclostreptin) pore sites and showed reduced binding of both compounds to resistant cell cytoskeletons. In contrast, CLIP-170S had no effect on peluroside whose MT binding does not require access through the pore. Together, these data indicate that CLIP-170S obstructs the MT pore, preventing drug access to the MT lumen and causing taxane resistance. Clinically, we found CLIP-170S to be expressed in ~60% of GC patient tumors and that its expression was significantly associated with resistance to cabazitaxel monotherapy. Computational analyses of RNAseq data from sensitive and resistant cells predicted Gleevec (Imatinib) as a drug that could overcome taxane resistance. Indeed, we showed that Gleevec reversed taxane resistance by specific depletion of CLIP-170S protein.

Taken together, these data reveal an entirely novel mechanism of taxane resistance via obstruction of the MT pore by the previously unrecognized CLIP-170S. We further found CLIP-170S to be highly prevalent in patient tumors and identified Gleevec as the first specific inhibitor of CLIP-170S.

Citation Format: Prashant V. Thakkar, Katsuhiro Kita, Giuseppe Galletti, Neel Madhukar, Elena Vila Navarro, Kyle Cleveland, Isabel Barasoain, Holly V. Goodson, Dan Sackett, Jose Fernando Diaz, Olivier Elemento, Manish A. Shah, Paraskevi Giannakakou. Systems biology identifies Gleevec as a specific inhibitor of CLIP-170S, a novel +TIP isoform, which causes taxane resistance in cancer cells and patients by obstructing the Microtubule pore [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 641.

Abstract 3817: Systems biology identifies that Gleevec reverses taxane resistance in solid tumors by selective inhibition of a novel +Tip microtubule-binding variant

The microtubule (MT) cytoskeleton is a validated therapeutic target in oncology, evidenced by the wide use of taxanes in solid tumors including gastric cancer (GC). Post-hoc analysis of the clinical trial that led to docetaxel approval in GC, revealed that patients with diffuse histological subtype were intrinsically resistant to taxane chemotherapy. Using a panel of GC cell lines intrinsically sensitive or resistant to taxanes, we showed lack of drug-target engagement in the resistant lines, despite unimpaired intracellular drug accumulation and absence of tubulin mutations. We discovered a novel, truncated variant of the MT +TIP binding protein CLIP1, hereafter CLIP1S, which was significantly enriched in the resistant cells. Mass-spec proteomics and 5’RACE showed that CLIP1S lacked the first 150 amino acids, thus, missing the Cap-Gly domain required for MT +TIP localization. Confocal microscopy of endogenous or exogenous tagged proteins revealed that CLIP1S was indeed mislocalized from the +TIP to the MT lattice in contrast to +TIP localization of canonical CLIP1. Stable CLIP1S-Knock Down (KD) entirely reversed taxane-resistance (~300 fold), establishing causation between CLIP1S and taxane resistance. Quantitation of drug-binding kinetics using live-cell imaging of Flutax-2 (fluorescently-labeled taxane) in native cytoskeletons, showed that CLIP1S caused Flutax-2 to have significantly reduced affinity and increased dissociation rates from MTs, as compared with cells expressing only the canonical CLIP1. CLIP1S-KD, fully restored Flutax-2 binding, implicating CLIP1S in impeding taxane-MT interaction. Co-administration of chemical probes specific for the low affinity taxane binding site on MT surface further implicated CLIP1S in partially obstructing the MT pore thereby restricting taxane access in the MT lumen where the high affinity taxane binding site is located. Computational analyses of RNA-seq data from untreated or taxane-treated sensitive and resistant GC cells using a novel bayesian drug-target identification algorithm predicted Imatinib (Gleevec™) as a drug that could overcome CLIP1S mediated taxane resistance. Indeed, imatinib completely reversed taxane resistance, phenocopying the sensitization observed with the CLIP1S-KD. Most importantly, we showed that imatinib reversed taxane resistance by specific inhibition of CLIP1S in a dose-dependent manner as early as 3 h post-treatment. Taken together, these data identify an entirely novel mechanism of taxane resistance that involves obstruction of the MT pore in the presence of a previously unknown +TIP variant. Through systems biology we identified imatinib as the first specific CLIP1S inhibitor, thereby repurposing imatinib as a novel therapeutic to overcome clinical taxane resistance in GC and beyond.

Citation Format: Prashant V. Thakkar, Katsuhiro Kita, Giuseppe Galletti, Neel S. Madhukar, Kyle Cleveland, Isabel Barasoain, Jose Fernando Diaz, Olivier Elemento, Manish A. Shah, Paraskevi Giannakakou. Systems biology identifies that Gleevec reverses taxane resistance in solid tumors by selective inhibition of a novel +Tip microtubule-binding variant [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3817.

Abstract 4169: A novel, short isoform of the +Tip microtubule binding protein CLIP170 confers taxane resistance in gastric cancer

The microtubule (MT) cytoskeleton is one of the most validated therapeutic targets in clinical oncology, as evidenced by the wide clinical activity of taxanes and other MT inhibitors. However, patients with intrinsic drug resistance do not benefit from taxane chemotherapy, such as patients with diffuse gastric cancer (GC). Currently, the molecular mechanisms underlying clinical taxane resistance remain poorly elucidated. Using a panel of GC cell lines with intrinsic sensitivity or resistance to taxanes, we showed lack of drug-target engagement in the resistant lines, despite unimpaired intracellular accumulation of the drug and in the absence of tubulin mutations or altered tubulin isotype expression. Herein, we show for the first time that the resistant cells expressed a novel, short isoform of the MT plus-end binding protein, CLIP170 (CLIP1). CLIP1 binds to the plus-ends of microtubules (+TIPs) and regulates dynein-mediated MT-based trafficking and the tubulin tyrosination cycle. We showed by both mass-spec proteomics and 5’-RACE that the short CLIP1 isoform (CLIP1S) lacks the first 150 amino acids, thus, missing the first Cap-Gly (Cytoskeleton-Associated Protein-Glycine) domain, which is required for proper +TIP localization. Indeed, confocal microscopy experiments showed that CLIP1S was mislocalized to the microtubule lattice in contrast to the canonical comet-like pattern of CLIP1 seen in taxane sensitive cell lines. CLIP1S expression was specifically correlated with taxane resistance (docetaxel, cabazitaxel) as no correlation was observed with other DNA-damaging agents. Since, CLIP1S expression has never been reported before, to establish causation, we stably knocked down CLIP1 and CLIP1S in taxane-sensitive and resistant cells, respectively. CLIP1SKD entirely reversed taxane-resistance (~300 fold) while CLIP1KD had no effect in the taxane-sensitive cell lines. These data suggest a gain-of-function of CLIP1S that leads to taxane resistance. To study the binding kinetics of taxanes to MTs in the presence or absence of CLIP1S we performed live cell imaging of native cytoskeletons using fluorescently-labeled paclitaxel (Flutax). Our data revealed significantly faster dissociation rates of Flutax from MTs in the resistant cells, indicating transient interaction with MTs. Taxane binding to MTs is a two-step process. First taxanes bind to the MT-pore low affinity surface site, which then facilitates access to the high affinity luminal site. Using a small molecule that binds only to MT-pore site, we showed that we showed that taxol binding to the pore is significantly slower in resistant cells expressing CLIP1S, which together with mislocalization of this variant along the MT lattice suggests that it obstructs access to the MT-pore thus restricting entry of taxane into the lumen of microtubules. This finding will have profound implications for taxane resistance as well as microtubule biology broadly.

Citation Format: Prashant V. Thakkar, Katsuhiro Kita, Giuseppe Galletti, Kyle Cleveland, Isabel Barasoain, Jose Fernando Diaz, Manish A. Shah, Paraskevi Giannakakou. A novel, short isoform of the +Tip microtubule binding protein CLIP170 confers taxane resistance in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4169. doi:10.1158/1538-7445.AM2017-4169

A national programme for patient and staff dose monitoring in interventional cardiology

A national programme on patient and staff dose evaluation in interventional cardiology made in cooperation with the haemodynamic section of the Spanish Society of Cardiology has recently been launched. Its aim is to propose a set of national diagnostic reference levels (DRLs) for patients as recommended by the International Commission on Radiological Protection and to initiate several optimisation actions to improve radiological protection of both patients and staff. Six hospitals have joined the programme and accepted to submit their data to a central database. First to be acquired were the quality control data of the X-ray systems and radiation doses of patients and professionals. The results from 9 X-ray systems, 1467 procedures and staff doses from 43 professionals were gathered. Provisional DRLs resulted in 44 Gy cm(2) for coronary angiography and 78 Gy cm(2) for interventions. The X-ray systems varied up to a factor of 5 for dose rates in reference conditions. Staff doses showed that 50 % of interventional cardiologists do not use their personal dosemeters correctly.

Purification and characterization of an 18-kd allergen of birch (Betula verrucosa) pollen: identification as a cyclophilin

BACKGROUND

Five birch pollen allergens have been identified so far. In a previous study we detected new birch pollen allergens with an isoelectric point in the range 9.0 to 9.3, present only in extracts prepared at controlled basic pH.

OBJECTIVE

The purpose of the current study was to purify and characterize those allergens.

METHODS

The target allergens were purified by ion exchange and hydrophobic interaction chromatography. Analyses were carried out by SDS-PAGE, isoelectric focusing, immunoblotting, and amino acid sequencing. The in vivo reactivity of the allergens was evaluated by skin testing.

RESULTS

An 18-kd protein, which we named Bet v 7, was purified. This 18-kd protein corresponded to 3 bands on isoelectric-focusing immunoblots that probably represent isoforms. On immunoblots up to 20.8% of birch pollen-allergic patients recognized those allergens. The clinical relevance of Bet v 7 was demonstrated by positive immediate-type skin testing on a patient allergic to birch pollen. Sequencing of an internal peptide yielded an amino acid sequence showing high homology with various plant cyclophilins. The rotamase activity of the protein, inhibited by cyclosporin A, further confirmed that Bet v 7 belongs to the group of cyclophilins.

CONCLUSION

We have purified a novel allergen of birch pollen, Bet v 7, belonging to the cyclophilin family. Because cyclophilins are highly conserved proteins over the phylogeny, we may postulate that Bet v 7 is a member of a new family of panallergens.

Exploring the longitudinal course of psychotic illness: a case-study approach

OBJECTIVE

Thirty-three patients with a diagnosis of a psychotic disorder (schizophrenia, bipolar disorder, atypical psychosis) according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) were studied to qualitatively assess the longitudinal course of the disorder using a case-study approach.

METHODS

Weekly fluctuations in patient symptomatology and overall social and personal functioning using the Global Assessment Scale were assessed following index hospitalization. Patients were followed for 1 year.

RESULTS

The emergent courses showed no relationship to diagnosis but followed 3 general trends: 1) positive incline; 2) fluctuating; and 3) stable. Individual representations of each course were examined closely, and biological and psychosocial factors associated with each were evaluated.

CONCLUSIONS

The results supported the longitudinal patterns and individual interactions of Strauss's Interactive Developmental Model. The clinical course of psychotic disorders may be represented by 3 patterns. Key factors in the interaction between patient and environment that generate important changes in the evolution of each illness were illustrated.

Calculation of pathways for the conformational transition between the GTP- and GDP-bound states of the Ha-ras-p21 protein: calculations with explicit solvent simulations and comparison with calculations in vacuum

The transitions between the water-equilibrated structures of the GTP and GDP forms of Ha-ras-p21 have been calculated by using the targeted molecular dynamics (TMD) method (Schlitter et al., Mol. Sim. 10:291-309, 1993) both in vacuo and with explicit solvent simulation. These constrained molecular dynamics calculations result in different pathways, depending on the nucleotide bound. Each pathway consists in a sequence of transitions affecting six segments of the protein, four of them forming a hydrophilic cleft around the nucleotide. The transitions are initiated by the removal or introduction of the gamma-phosphate of the nucleotide and proceed sequentially, crossing several low-energy transition states. The movements are transmitted either by direct interactions between the segments or through the nucleotide. The GTP to GDP pathway is initiated by the removal of the nucleotide gamma-phosphate. This gives some space to Gly12, Gly13, and Val14. Their movement is transmitted to the target recognition domain and the switch II region, forcing these segments to adopt another position. In a second step the target recognition domain and the switch II region undergo conformational transitions to reach an intermediate conformation. Finally, there is a relaxation of the target recognition domain to its final state that forces the switch II region to reach its target conformation. The calculated pathways allow the identification of many residues that play an important role in the conformational changes, explain the altered transformation properties of some, and suggest mutations to alter the pathway.

Asymptomatic and symptomatic cryptosporidiosis: their acute effect on weight gain in Peruvian children

This study investigated whether a child's first infection with Cryptosporidium parvum had an acute effect on weight gain. Specifically, the authors compared monthly rates of weight gain between C. parvum-infected and noninfected children. Over a 2-year period (1989-1991), a cohort of Peruvian children aged 0-3 months at recruitment were followed twice weekly for assessment of daily diarrheal status, weekly for C. parvum stool examinations, and monthly for anthropometric measurements. Data on 207 children permitted the authors to examine the effect of C. parvum infection on weight gain. During the 2-year study period, 45% (94/207) of the children became infected with C. parvum for the first time. Weight gain intervals in 57 of the 94 infected children met criteria for analysis. Of these, 63 percent (36/57) were asymptomatic (i.e., had no diarrhea). On average, children with symptomatic cryptosporidiosis gained (i.e., grew) 342 g less (95% confidence interval 167-517) during the first month of infection than did children without diarrhea who were not yet infected. The effect of asymptomatic cryptosporidiosis was less severe: On average, children with asymptomatic infection gained 162 g less (95% confidence interval 27-297) during the first month of infection than did children without diarrhea who were not yet infected. Symptomatic cryptosporidiosis retarded weight gain more than did asymptomatic cryptosporidiosis, but the latter was twice as common. Since asymptomatic cryptosporidiosis is more prevalent, it may have more of an overall adverse effect on child growth in the community than symptomatic cryptosporidiosis.

Surgical treatment of testicular trauma: effects on fertility and testicular histology

Unilateral testicular trauma in the postpubertal male can lead to alterations in semen analysis, but it is not clear what effect this has on fertility. To better understand how surgical treatment of testicular trauma affects both fertility and testicular histology the following study was performed. Eighty postpubertal Lewis rats were divided into eight equal groups with one group serving as a control. In the 70 remaining rats the left testicle was subjected to blunt or penetrating injury. The testicles were either left untreated, were removed, or were repaired with sutures or mesh before being returned to the scrotum. Following recovery, each male was allowed to mate to determine fertility. Fertility rates were significantly lower in all postinjury groups except the postinjury orchiectomy group. Histological analyses showed nonspecific inflammation, smaller tubules, and impaired spermatogenesis in all postinjury testicles regardless of the type of treatment. Contralateral testicles had no evidence of autoimmune injury and were essentially identical to the control group. In the postpubertal Lewis rat, unilateral testicular trauma leads to impaired fertility unless the injured testicle is removed soon after the injury. Various methods of repairing the injury did not improve fertility. In spite of the impaired fertility, the contralateral testicle appears histologically normal.

Structural intermediates in the assembly of taxoid-induced microtubules and GDP-tubulin double rings: time-resolved X-ray scattering

We have studied the self-association reactions of purified GDP-liganded tubulin into double rings and taxoid-induced microtubules, employing synchrotron time-resolved x-ray solution scattering. The experimental scattering profiles have been interpreted by reference to the known scattering profiles to 3 nm resolution and to the low-resolution structures of the tubulin dimer, tubulin double rings, and microtubules, and by comparison with oligomer models and model mixtures. The time courses of the scattering bands corresponding to the different structural features were monitored during the assembly reactions under varying biochemical conditions. GDP-tubulin essentially stays as a dimer at low Mg(2+) ion activity, in either the absence or presence of taxoid. Upon addition of the divalent cations, it associates into either double-ring aggregates or taxoid-induced microtubules by different pathways. Both processes have the formation of small linear (short protofilament-like) tubulin oligomers in common. Tubulin double-ring aggregate formation, which is shown by x-ray scattering to be favored in the GDP- versus the GTP-liganded protein, can actually block microtubule assembly. The tubulin self-association leading to double rings, as determined by sedimentation velocity, is endothermic. The formation of the double-ring aggregates from oligomers, which involves additional intermolecular contacts, is exothermic, as shown by x-ray and light scattering. Microtubule assembly can be initiated from GDP-tubulin dimers or oligomers. Under fast polymerization conditions, after a short lag time, open taxoid-induced microtubular sheets have been clearly detected (monitored by the central scattering and the maximum corresponding to the J(n) Bessel function), which slowly close into microtubules (monitored by the appearance of their characteristic J(0), J(3), and J (n) - (3) Bessel function maxima). This provides direct evidence for the bidimensional assembly of taxoid-induced microtubule polymers in solution and argues against helical growth. The rate of microtubule formation was increased by the same factors known to enhance taxoid-induced microtubule stability. The results suggest that taxoids induce the accretion of the existing Mg(2+)-induced GDP-tubulin oligomers, thus forming small bidimensional polymers that are necessary to nucleate the microtubular sheets, possibly by binding to or modifying the lateral interaction sites between tubulin dimers.

Experimental and theoretical study of electrostatic effects on the isoelectric pH and the pKa of the catalytic residue His-102 of the recombinant ribonuclease from Bacillus amyloliquefaciens (barnase)

Barnase, the guanine specific ribonuclease of Bacillus amyloliquefaciens, was subjected to mutations in order to alter the electrostatic properties of the enzyme. Ser-85 was mutated into Glu with the goal to introduce an extra charge in the neighborhood of His-102. A double mutation (Ser-85-Glu and Asp-86-Asn) was introduced with the same purpose but without altering the global charge of the enzyme. A similar set of mutations was made using Asp at position 85. For all mutants the pI was determined using the technique of isoelectric focusing and calculated on the basis of the Tanford-Kirkwood theory. When Glu was used to replace Ser-85, the correlation between the experimental and the calculated values was perfect. However, in the Ser-85-Asp mutant, the experimental pI drop is bigger than the calculated one, and in the double mutant (Ser-85-Asp and Asp-86-Asn) the compensation is not achieved. The effect of the mutations on the pKa of His-102 can be determined from the pH dependence of the kcat/KM for the hydrolysis of dinucleotides, e.g., GpC. The effect can also be calculated using the the method of Honig. In this case the agreement is very good for the Glu-mutants and the single Asp-mutant, but less for the double Asp-mutant. The global stability of the Asp-mutants is, however, the same as the wild type, as shown by stability studies using urea denaturation. Molecular dynamics calculations, however, show that in the double Asp-mutant His-102 (H+) swings out of its pocket to make a hydrogen bridge with Gin-104 which should cause an additional pKa rise. The effect of the Glu-mutations was also tested on all the kinetic parameters for GpC and the cyclic intermediate G > p at pH 6.5, for RNA at pH 8.0, and for poly(A) at pH 6.2. The effect of the mutations is rather limited for the dinucleotide and the cyclic intermediate, but a strong increase of the KM is observed in the case of the single mutant (extra negative charge) with polymeric substrates. These results indicate that the extra negative charge has a strong destabilizing effect on the binding of the polymeric substrates in the ground state and the transition state complex. A comparison with the structure of bound tetranucleotides (Buckle, A.M. and Fersht, A.R., Biochemistry 33:1644-1653, 1994) shows that the extra negative charge points towards the P2 site.

Use of tubularized peritoneal free grafts as urethral substitutes in the rabbit

As an alternative to bladder mucosa, free grafts of tubularized peritoneum were used as urethral substitutes in a rabbit model of hypospadias. In group 1, six mature rabbits underwent partial penile urethrectomy followed by interposition of a 2-cm-long peritoneal-lined tube graft. These animals had urethrograms performed at 3 months and were killed at 6 (n = 4) or 12 (n = 2) months. In group 2, six rabbits underwent total penile urethrectomy with placement of 3-cm-long grafts. These animals were killed 1 to 4 weeks after surgery. Clinical assessment and gross examination of the 12 rabbits showed no urinary retention, two small fistulas at the proximal anastomosis, and no strictures or diverticular. At 6 and 12 months (group 1) the urethra had healed completely and the graft edges were not visible. In group 2, 1 to 4 weeks after surgery the graft was intact and the interface between the graft and native urethra was visible. Histological studies of the grafts were compared with control peritoneum. At 1 week, a high-density single-cell layer was present. Beginning at 2 weeks, a multilayered epithelium was present, which became more organized in the older grafts. Neovascularity became visible in the subepithelial layer at 2 weeks. Acute inflammatory cells were present early and were replaced by a palisading layer of lymphocytes and plasma cells in the older grafts. Minimal fibrosis was observed. Tubularized peritoneal free grafts are a promising new urethral substitute. Graft placement is technically simple. Replacement of the peritoneum by a multilayered epithelium resembling transitional epithelium occurs early after graft placement. As much as 1 year later, minimal scarring is present.

Discrepancies between cerebral computed tomography and western blot in the diagnosis of neurocysticercosis. The Cysticercosis Working Group in Peru (Clinical Studies Coordination Board)

Serum samples from sequential patients who underwent cerebral computed axial tomography (CT) scan in a Peruvian radiologic clinic were tested by the highly sensitive and specific enzyme-linked immunoelectrotransfer blot (EITB) test to detect antibodies to Taenia solium. The results of the EITB test were compared with those obtained by CT scan for the diagnosis of neurocysticercosis. Of the 383 patients sampled, 32 (8%) were seropositive. The results of CT and EITB were frequently discrepant. When compared with the EITB assay, the CT scan was 44% sensitive and 95% specific. The sensitivity of CT increased to 63% if less specific images (single calcifications, granulomas, or hydrocephalus) were included. The CT scan for diagnosis of cysticercosis can best be used in conjunction with a reliable serologic test such as the EITB.

Branching patterns of right pulmonary artery in cardiovascular anomalies

The branch of the right pulmonary artery (RPA) to the upper lobe of the right lung (RUL), the truncus anterior of the RPA, and the pars anterior of the left pulmonary artery, which supplies the left upper lung lobe (LUL), were demonstrated by both dissection of postmortem specimens and angiography for 20 infants and children, by angiography only for 57, and by specimen dissection only for 59 (total 136). In posteroanterior angiograms, the RUL artery branches from the RPA near the right lateral border of the vertebral column, while the LUL artery or arteries arise more laterally, near the left midclavicular plane. This pattern is reversed in situs inversus (eight patients studied). Thirty-nine patients in other categories of congenital cardiovascular disease showed an abnormal RUL or LUL arterial pattern, including pulmonary isomerism, right lung type (RUL artery pattern present bilaterally, 12 patients); pulmonary isomerism, left lung type (RUL artery pattern absent bilaterally, 11 patients); scimitar syndrome (RUL artery pattern normal, 1 patient; absent bilaterally, 4 patients); and left pulmonary artery sling (RUL artery normal, one; hypoplastic, one; absent, two patients). Five patients with tetralogy of Fallot (TOF) with right aortic arch (RAA) and 1 of 15 with RAA not TOF or situs inversus showed a relatively large RUL artery arising more laterally than usual. Three of six patients with double outlet right ventricle had the LUL artery larger than usual plus two accessory RUL arteries, and one patient with crossed pulmonary arteries showed a similar pattern. Two patients with single ventricle had an RUL artery of normal pattern although the RUL bronchus was absent, and one patient with single ventricle and situs inversus had a comparable pattern in the left lung. The ease of demonstration of the right and left upper lobe branches of the pulmonary artery by dissection or angiocardiography warrants greater attention to their patterns in patients with congenital cardiovascular disease. Dissociation of upper lobe bronchial and vascular patterns is unusual and may also be of diagnostic value.

Low resolution structure of microtubules in solution

The structure of microtubules has been characterized to 3 nm resolution employing time-resolved X-ray scattering. This has revealed detailed structural features of microtubules not observed before in solution. The polymerization of highly purified tubulin, induced by the antitumour drug taxol, has been employed as a microtubule model system. This assembly reaction requires Mg2+, is optimal at a 1:1 taxol to tubulin heterodimer molar ratio, proceeds with GTP or GDP and is intrinsically reversible. The X-ray scattering profiles are consistent with identical non-globular alpha and beta-tubulin monomers ordered within the known helical surface lattice of microtubules. Purified tubulin-taxol microtubules have a smaller mean diameter (approx. 22 nm) than those induced by microtubule associated proteins or glycerol (approx. 24 nm), but nearly identical wall substructure to the resolution of the measurements. This is because the majority of the former consist of only 12 protofilaments instead of the typical 13 protofilaments, as confirmed by electron microscopy of thin-sectioned, negatively stained and ice-embedded taxol microtubules. It may be concluded that taxol induces a slight reduction of the lateral contact curvature between tubulin monomers. The main fringe pattern observed in cryo-electron micrographs is consistent with a simple 12 protofilament 3-start skewed lattice model. Cylindrical closure of this lattice can be achieved by tilting the lattice 0.8 degrees with respect to the microtubule axis. The closure implies a discontinuity in the type of lateral contacts between the tubulin monomers (regardless of whether these are of the -alpha-beta- or the -alpha-alpha-/-beta-beta- type), which indicates that lateral contacts and the subunit specificity of taxol binding are, to a large degree, equivalent.

Immunodiagnosis of human cysticercosis (Taenia solium): a field comparison of an antibody-enzyme-linked immunosorbent assay (ELISA), an antigen-ELISA, and an enzyme-linked immunoelectrotransfer blot (EITB) assay in Peru. The Cysticercosis Working Group in Peru (CWG)

We compared results of an enzyme-linked immunosorbent assay (ELISA) and an enzyme-linked immunoelectrotransfer blot (EITB) assay for the diagnosis of cysticercosis in sera and cerebrospinal fluid (CSF). Sera from 34 patients with confirmed cysticercosis were tested by both ELISA and EITB assays. Cerebrospinal fluid from some of these patients was also tested by ELISA for the presence of antibody (AB-ELISA) (n = 21) and antigen (AG-ELISA) (n = 15). Specificity in sera was examined by testing 51 serum samples from Bangladesh, where cysticercosis is not endemic. Cross-reactivity was evaluated in sera from patients with Echinococcus granulosus (hydatid) and Hymenolepis nana infections. Sensitivity in detecting cysticercosis in sera was 94% by EITB and 65% by AB-ELISA (P less than 0.01). Sensitivities in the CSF tested by EITB, AB-ELISA, and AG-ELISA were 86%, 62%, and 67%, respectively. The specificity of the EITB was 100%, while that of AB-ELISA was 63% (P less than 0.01). Cross-reactions occurred in the AB-ELISA with 11% and 20% of sera from hydatid and H. nana patients, respectively. Our results demonstrate that the EITB is the best assay available for the diagnosis of cysticercosis in both sera and CSF.

Clinical correlates of white-matter changes on magnetic resonance imaging scans of the brain

We report our observations on the clinical and radiologic correlates of changes in cerebral white matter based on 94 subjects undergoing magnetic resonance imaging in a prospective study of dementia. Periventricular hyperintensity occurred twice as often in patients with Alzheimer's disease as in healthy control subjects. Within the control group, the presence of periventricular hyperintensity correlated significantly with one measure of cerebral atrophy and with the presence of changes in the adjoining deep white matter. The significance of white-matter changes distinct from the ventricles (leuko-araiosis) remains unsettled. Leuko-araiosis on the magnetic resonance imaging scan, unlike its correlate on the computed tomographic scan, was not shown to relate to cognitive decline or to the presence of focal abnormalities on neurologic examination. This is likely to reflect the heterogeneity of the changes detected with magnetic resonance imaging and their limited extent in our subjects.

Improved recognition of leukoaraiosis and cognitive impairment in Alzheimer's disease

We identified 85 patients in a longitudinal study of dementia who had uncomplicated Alzheimer's disease and in whom computed tomography of the head and psychometric testing were conducted within a 6-month period following their entry into the study. Thirty-four patients (40%) had leukoaraiosis, which was disproportionately common in female patients (62% vs 15% in male patients). Analysis of covariance demonstrated a relative reduction of scores on the Extended Scale for Dementia in those patients who had leukoaraiosis, after adjusting for the confounding effects of age, sex, educational level, and duration of illness. Leukoaraiosis was also much more common in women, even after adjusting for the possible confounding effects of age, duration of illness, Extended Scale for Dementia score, and hypertension. Multiple regression analysis showed that leukoaraiosis accounted for 11.6% of the variance of the Extended Scale for Dementia scores. Leukoaraiosis, together with duration of illness, accounted for 18.2% of the variance. Leukoaraiosis is associated with a greater degree of cognitive impairment in patients with Alzheimer's disease.

A cross-sectional study of pulmonary function in carbon black workers in the United States

Since a proportion of airborne carbon black particles is of respirable size, the possibility that it may affect pulmonary function was investigated in 913 employees of 6 carbon black producers in the United States. Exposure was estimated by combining the mean total dust exposures of each job category with the length of time workers had spent in each job, giving a measurement expressed in mg/m3.months. Pulmonary function was measured by spirometry. The major variables affecting pulmonary function were age and cigarette smoking. When the effects of age and smoking were controlled in an age-specific, two-way analysis of variance, no consistent effects of total dust exposure were detectable in these workers. This study provided no evidence that exposure to total dust under the conditions pertaining in the contemporary carbon black industry had detrimental effects on the pulmonary function of men employed in the production and handling of this product.

Aggregation of multiple risk factors for stroke in siblings of patients with brain infarction and transient ischemic attacks

Hypertension, heart disease, and diabetes are not only the major risk factors for stroke, but they tend to cluster in families. It is unknown, however, whether these conditions occur more frequently among relatives of patients with specific types of stroke as compared to non-relatives. The frequencies of stroke and its major risk factors in two groups of subjects were compared. One group consisted of 76 siblings of 41 patients hospitalized with cerebral infarction and transient ischemic attacks in an investigative stroke unit; the other consisted of 55 siblings of the patients' spouses. The occurrence of these conditions in the relatives was determined from a questionnaire completed by the relatives and supported by information from the relatives' family physicians. When considered separately, hypertension, heart disease, and stroke occurred in a small but not statistically significant excess among the relatives in-law. However, various combinations of two or three diseases, (including diabetes), occurred in 20.9% of the patients' siblings as compared to only 3.6% of the relatives in-law (p less than 0.001). These results suggest that living siblings of patients with cerebral infarction and transient ischemic attacks may have an increased risk of stroke and cardiovascular disease as a result of multiple risk factors operating simultaneously. Prevention programs among this high risk population may be particularly worthwhile.