Factors Associated With Reasons for Living Among Suicidal Adolescents

OBJECTIVE

The objective of this study was to identify baseline demographic and clinical factors associated with higher scores on the Reasons for Living Inventory for Adolescents (RFL-A) at baseline and over follow-up.

METHOD

Using data from a pilot clinical trial of a brief intervention for suicidal youth transitioning from inpatient to outpatient, we identified univariate associations of baseline characteristics with RFL-A and used regression to identify the most parsimonious subset of these variables. Finally, we examined to what extent changes in these characteristics over time were related to changes in RFL-A.

RESULTS

Univariate analyses found that better external functional emotion regulation and social support were associated with higher RFL-A scores; more self-reported depression, internal dysfunctional emotion regulation, sleep disturbance, anxiety, and distress tolerance were associated with lower RFL-A scores. Multiple linear regression identified internal dysfunctional emotion regulation and external functional emotion regulation as the most parsimonious set of characteristics associated with RFL-A. Improvement in internal emotion regulation, sleep, and depression were related to improvements in RFL-A over time.

CONCLUSION

Our findings indicate that emotion regulation-specifically maladaptive internal strategies and use of external resources-is strongly associated with RFL-A. Improvements in internal emotion regulation (r = 0.57), sleep (r = -0.45), and depression (r = -0.34) were related to increases in RFL-A.

Robust engraftment of fetal nonhuman primate CD34-positive cells in immune-deficient mice

Nonhuman primates (NHPs) represent one of the most important models for preclinical studies of novel biomedical interventions. In contrast with small animal models, however, widespread utilization of NHPs is restricted by cost, logistics, and availability. Therefore, we sought to develop a translational primatized mouse model, akin to a humanized mouse, to allow for high-throughput in vivo experimentation leveraged to inform large animal immunology-based studies. We found that adult rhesus macaque mobilized blood (AMb) CD34+-enriched hematopoietic stem and progenitor cells (HSPCs) engrafted at low but persistent levels in immune-deficient mice harboring transgenes for human (NHP cross-reactive) GM-CSF and IL3, but did not in mice with wild-type murine cytokines lacking NHP cross-reactivity. To enhance engraftment, fetal liver-derived HSPCs were selected as the infusion product based on an increased CD34hi fraction compared with AMb and bone marrow. Coupled with cotransplantation of rhesus fetal thymic fragments beneath the mouse kidney capsule, fetal liver-derived HSPC infusion in cytokine-transgenic mice yielded robust multilineage lymphohematopoietic engraftment. The emergent immune system recapitulated that of the fetal monkey, with similar relative frequencies of lymphocyte, granulocyte, and monocyte subsets within the thymic, secondary lymphoid, and peripheral compartments. Importantly, while exhibiting a predominantly naïve phenotype, in vitro functional assays demonstrated robust cellular activation in response to nonspecific and allogenic stimuli. This primatized mouse represents a viable and translatable model for the study of hematopoietic stem cell physiology, immune development, and functional immunology in NHPs. Summary Sentence: Engraftment of rhesus macaque hematopoietic tissues in immune-deficient mice yields a robust BLT/NeoThy-type primatized mouse model for studying nonhuman primate hematopoiesis and immune function in vivo.

FRI0195 ULTRASONOGRAPHIC HALO SCORE ASSOCIATES WITH INTIMAL HYPERPLASIA IN GIANT CELL ARTERITIS

Background:

We have recently developed a novel ultrasonographic Halo Score to quantify the extent of vascular inflammation in GCA [1]. High Halo Scores were associated with a high rate of ocular ischaemia among patients with GCA. Earlier studies have shown that GCA patients with intimal hyperplasia in their temporal artery biopsy (TAB) are at the highest risk of neuro-ophthalmic, ischaemic complications [2,3]. We therefore questioned whether the ultrasonographic Halo Score might be linked to the presence of intimal hyperplasia in patients with GCA.

Objectives:

To investigate the relationship between the ultrasonographic Halo Score and intimal hyperplasia.

Methods:

This is a prospective study including 92 patients suspected of having GCA, who underwent both ultrasound of temporal/axillary arteries and TAB at diagnosis. Ultrasonographic halo counts and Halo Scores were determined [1]. An experienced pathologist determined whether or not the TAB findings were consistent with GCA. TABs were systematically evaluated for the presence of a transmural infiltrate and intimal hyperplasia. Multiple linear regression analysis was performed with either halo counts or Halo Scores as the dependent variable. Predictive variables included the presence of a transmural TAB infiltrate, intimal hyperplasia and male sex.

Results:

The TAB was consistent with GCA in 27 patients. The TAB revealed transmural inflammation in 18 patients and giant cells in 24 patients. Intimal hyperplasia was found in 20 patients with a positive TAB. Patients with a positive TAB showed higher halo counts and Halo Scores than patients with a negative TAB. Overall, patients with a positive TAB and intimal hyperplasia presented with the highest halo counts and Halo Scores (Figure). Among patients with a positive TAB, only intimal hyperplasia and male sex were predictive of higher halo counts and Halo Scores in the multiple linear regression analysis. Ocular ischaemia was present in 14% of patients with a positive TAB without intimal hyperplasia. However, 40% of patients with a positive TAB and intimal hyperplasia suffered from ocular ischaemia.

Conclusion:

The ultrasonographic Halo Score is strongly influenced by the presence of intimal hyperplasia, a TAB feature that associates with cranial ischemic complications in patients with GCA [2,3].

References:

[1]van der Geest KSM, Borg F, Kayani A, Paap D, Gondo P, Schmidt W, et al. Novel ultrasonographic Halo Score for giant cell arteritis: assessment of diagnostic accuracy and association with ocular ischaemia. Annals of the Rheumatic Diseases 2020 Jan 3.

[2]Makkuni D, Bharadwaj A, Wolfe K, Payne S, Hutchings A, Dasgupta B. Is intimal hyperplasia a marker of neuro-ophthalmic complications of giant cell arteritis? Rheumatology (Oxford, England) 2008 Apr;47(4):488-490.

[3]Kaiser M, Weyand CM, Bjornsson J, Goronzy JJ. Platelet-derived growth factor, intimal hyperplasia, and ischemic complications in giant cell arteritis. Arthritis and Rheumatism 1998 Apr;41(4):623-633.

Figure

Disclosure of Interests:

Kornelis van der Geest Speakers bureau: Roche (2019), Frances Borg: None declared, Konrad Wolfe: None declared, Wolfgang A. Schmidt Grant/research support from: GSK, Novartis, Roche, Sanofi, Consultant of: GSK, Novartis, Roche, Sanofi, Chugai, Raashid Luqmani Grant/research support from: Arthritis UK, the Medical Research Council, the University of California San Francisco/Oxford Invention Fund, the Canadian Institutes of Health Research, The Vasculitis Foundation, GSK, Consultant of: GSK, Medpace, MedImmune, Roche, Bhaskar Dasgupta Grant/research support from: Roche, Consultant of: Roche, Sanofi, GSK, BMS, AbbVie, Speakers bureau: Roche

Prevalence of attention deficit hyperactivity disorder symptoms in patients with schizophrenia

OBJECTIVE

To investigate the frequency of childhood and adult attention deficit hyperactivity disorder (ADHD) symptoms in a cohort of patients with schizophrenia (SCZ).

METHODS

A systematic review was conducted to evaluate existing evidence. Two self-report questionnaires were used to investigate adult ADHD and childhood ADHD symptoms in 126 patients with ICD-10 diagnoses of SCZ.

RESULTS

Five studies were included in the systematic review, with the prevalence of childhood and adult ADHD in SCZ subjects ranging between 17-57% and 10-47% respectively. Within our cohort, 47% of patients reported positive screening for ADHD symptoms either in childhood or adulthood. 23% reported symptomatology consistent with both childhood and adult ADHD.

CONCLUSIONS

We demonstrate a greater presence of ADHD symptomatology in SCZ compared to that reported for ADHD in the general population. Our findings highlight the importance of improved clinical assessment and treatment considerations in a subgroup of patients with SCZ.

Generation and characterization of phage-GnRH chemical conjugates for potential use in cat and dog immunocontraception

Overpopulation of cats and dogs is a serious worldwide problem that demands novel, safe and cost-effective solutions. The objective of this study was to generate and characterize phage-peptide conjugates with gonadotropin-releasing hormone (GnRH) for potential use as an immunocontraceptive. A filamentous phage vector f5-8 with wild-type phage coat proteins was used as a carrier for construction of chemical conjugates with GnRH, a peptide that acts as a master reproductive hormone. In such conjugates, the phage body plays the role of a carrier protein, while multiple copies of GnRH peptide stimulate production of neutralizing anti-GnRH antibodies potentially leading to contraceptive effects. To generate the constructs, four different GnRH-based peptides were synthesized and conjugated to phage particles in a two-step procedure: (i) peptides were reacted with phage to form a conjugate using 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride chemistry (EDC) and (ii) the conjugates were separated from remaining free peptides by dialysis. Formation and specificity of phage-GnRH conjugates were confirmed by three independent methods: spectrophotometry, electron microscopy and ELISA. When the conjugates were tested for interaction with sera collected from cats and dogs immunized with GnRH-based vaccines in independent studies, strong specific ELISA signals were obtained, suggesting the potential use of the conjugates for cat and dog immunosterilization. The ability of the conjugates to stimulate production of anti-GnRH antibodies in vivo was evaluated in mice. While optimization of dose, immunization route and adjuvant still requires investigation, our preliminary results demonstrated the presence of anti-GnRH antibodies in sera of mice immunized with such conjugates. Fertility trials in cats and dogs will be needed to evaluate contraceptive potentials of the phage-GnRH peptide chemical conjugates.

Is intimal hyperplasia a marker of neuro-ophthalmic complications of giant cell arteritis?

OBJECTIVE

The ischaemic complications of giant cell arteritis (GCA) such as blindness and stroke may result from luminal narrowing of the affected arteries. This study focuses on the association between the severity of intimal proliferation on temporal artery biopsy (TAB) histology and neuro-ophthalmic complications (NOCs) of GCA.

METHOD

We identified 30 cases of biopsy-proven temporal arteritis. One histopathologist (blinded to the clinical details) evaluated the TAB specimens and categorized the degree of maximum stenosis due to intimal hyperplasia into four grades: grade 1 is <50% luminal occlusion due to intimal hyperplasia, grade 2 is 50-75%, grade 3 is >75% and grade 4 is complete luminal occlusion. A second histopathologist (also blinded to the clinical details) independently evaluated the TAB specimens using the same grading system. The NOCs in these patients were noted after a case record review.

RESULTS

Of the 30 patients, 12 had NOC-10 with eye complications (complete visual loss, anterior ischaemic neuropathy, visual field defects), one patient had cerebral infarcts and one had both cerebral infarcts and vision loss. There was evidence for a statistically significant trend of NOC associated with higher intimal hyperplasia scores (P = 0.001). The scores of the histopathologists agreed for 23 (77%) patients and differed by 1 category for the remaining 7 (kappa-statistic 0.88).

CONCLUSIONS

Our study suggests that the degree of intimal hyperplasia on TAB histology (routinely available to all hospital units) seems to be closely associated with NOCs of GCA. The study highlights the possible prognostic as well as diagnostic role of the biopsy. We feel that intimal hyperplasia noted in biopsy specimens may help us in the risk stratification of GCA patients and targeting of appropriate and novel therapies.

GLUT-1: an extra diagnostic tool to differentiate between haemangiomas and vascular malformations

The differential diagnosis between juvenile haemangiomas, vascular malformations, pyogenic granulomas and normally proliferative endothelium (granulation tissue) on the basis of histology alone is sometimes difficult. This is important because haemangiomas, are self-limiting and vascular malformations are not. We report our experience of using the immunohistochemical marker GLUT-1 to distinguish haemangiomas from vascular malformations following the initial report by North and Colleagues (1998). We studied a total of 50 specimens from patients with vascular anomalies, and found that GLUT-1 reactivity was positive in 18 out of 19 juvenile haemangiomas, negative in two out of two noninvoluting congenital haemangiomas (NICH) and negative in 29 out of 29 vascular malformations, that included capillary malformations, lymphatic malformations, venous malformations and arteriovenous malformations (95% sensitivity, 100% specificity). Pyogenic granulomas (n = 4) and granulation tissue samples (n = 4) were used as negative controls. Placenta tissue was used as positive control. GLUT-1 accurately distinguishes haemangiomas from vascular malformations, and as a result from this work, we use this technique in routine histopathological differentiation of vascular anomalies.

The sequence of the human genome

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

Tall cell variant: an aggressive form of papillary thyroid carcinoma

Twenty-four cases of the tall cell variant (TCV), a subset of papillary thyroid carcinoma, were identified in a group of 624 patients with thyroid cancer. All pathology specimens were reviewed, and each patient's carcinoma was categorized according to characteristics on presentation, local recurrence, distant metastases, follow-up, and tumor-related mortality. The TCV group was compared with a historical control group (Mazzaferri and Jhiang: 1355 patients). The TCV group had a statistically higher percentage of stage 3 and 4 carcinoma, extrathyroidal invasion, and tumor size less than 1.5 cm than the control group. There was no statistical relationship between age greater than 50 years and stage in the TCV group. No relationship could be found between TCV histology and recurrence or mortality. These findings, combined with those of studies that link stage on presentation to poor outcomes, have led to our conclusion that TCV is an aggressive malignancy warranting appropriate treatment and close follow-up.

What is the real clinical utility of echocardiography? A prospective observational study

This was a prospective, structured interview to evaluate physician expectations of echocardiography and the subsequent impact on patient care. The setting involved requests for echocardiograms in patients admitted to a tertiary care teaching hospital. Measurements included assessment of the diagnostic and therapeutic implications of echocardiography perceived by the physicians and subsequently reported and confirmed by blinded chart review. From January to May 1997, 542 echocardiograms were performed on 500 inpatients (age 62 +/- 17 years; 56% men). Referring physicians were mainly house staff (83%) and from medical services. The main indications were evaluation of left ventricular function (54%) or valve function (16%). At the time of the request, 89% of physicians believed that echocardiography was needed to guide future investigations or treatment, although in 24% of cases, physicians could not provide details of such. A reported change in treatment occurred in 57% and was validated by chart review in 38%. Changes occurred more frequently in patients in the intensive care unit versus those not in the intensive care unit (54% vs 37%, P =.02) but were similar between attending physicians and house staff (frequency of change 41% vs 39%, P = not significant) and between those with and those without previous echocardiograms (38% vs 39%, P = not significant). The utility of the echocardiogram to influence treatment decisions in hospitalized patients is high, especially in critically ill patients. However, this impact is less than is anticipated at the time of the initial request. Further studies involving more select populations of patients are required.

Return to work

Worker's compensation isn't just for hard hats anymore. Occupational health strategies may be a lucrative launch-pad for hospitals interested in forming deeper relationships with employers.

Restoring a fair workers' compensation system for employer and employee

The costs of workers' compensation have curtailed in recent years, perhaps in part as a result of MCO's efforts in this area. Managed care organizations that consider jumping into the workers' compensation arena often make basic errors in developing their programs and networks. The author reminds MCOs of the practical points they need to consider.

Distribution of nerve fibers in the standard incision for carpal tunnel decompression

Twenty-two paired biopsy specimens of skin and subcutaneous tissue from the proximal and distal halves of the conventional curvilinear incision or carpal tunnel decompression were histologically examined. The specimens were immunohistochemically stained with S100 antibody to highlight the nerve fibers. The mean count of free nerve endings in the proximal biopsy site was 4.42/mm2 (SD, 2.97; range, 1.23-12.27), compared to 4.2/mm2 (SD, 2.71; range, 1.01-10.50) in the distal biopsy specimens. This difference was not statistically significant (p = .20, Wilcoxon's signed ranks [matched pairs] test). The proximal incision site for carpal tunnel decompression did not appear to be more neuroreceptive than the distal incision site, providing no support for the implication of proximal incision sites in proximal scar tenderness.

Absence of over-expression of p53 protein in benign and malignant paragangliomas

Expression of abnormally stable mutant forms of the protein encoded by the gene known as p53 is an extremely common event in human neoplasms, a fact reflecting its crucial role in the regulation of cell turnover. Although widely investigated in a range of tumours from a variety of sites, there do not, to our knowledge, appear to have been any studies of its expression in paragangliomas. Abnormal expression of p53 protein was absent from 15 morphologically typical adrenal (2) and extra-adrenal(13) paragangliomas, 3 were overtly malignant, when sought for using the DO-7 antibody (Dako), whilst colon adenocarcinomas known to abnormally express the protein and used as controls were consistently positive. These results suggest that the mechanism of any dysfunction of the p53 encoding gene in paragangliomas might differ from that in tumours from other sites such that its detectable overexpression does not result.

Induction of a dose-related increase in sulfobromophthalein uptake velocity in freshly isolated rat hepatocytes by phenobarbital

To determine whether phenobarbital affects hepatocellular bilirubin/sulfobromophthalein uptake mechanism, we administered it to male Sprague-Dawley rats, body weight 175 +/- 25 gm, at doses of 1 to 75 mg/kg body wt/day for 7 days. Control rats were given an equivalent volume of physiological saline solution. On day 8, hepatocytes were isolated by means of collagenase perfusion, suspended in Hanks' solution without albumin and incubated with high specific activity (3 Ci/mmol) [35S]sulfobromophthalein, which was synthesized in our laboratory and purified by means of a new reverse-phase high-pressure liquid chromatography procedure. The initial uptake rate of sulfobromophthalein was determined at sulfobromophthalein concentrations of 1 to 50 mumol/L with a rapid filtration technique. The maximum uptake velocity and Michaelis constant for sulfobromophthalein uptake at each phenobarbital dose were determined by means of a computer analysis. In control studies, maximum uptake and Michaelis constant were 48.0 +/- 16.7 (mean +/- S.D.) pmol/50,000 cells/min and 22 +/- 4 mumol/L, respectively. Maximum uptake velocity increased linearly with the log of the phenobarbital dose (r = 0.98, p < 0.01), the increase achieving statistical significance at a dose of 3 mg/kg/day. Michaelis constant, however, was essentially unchanged at phenobarbital doses of 50 mg/kg/day or less. The maximal observed increase in maximum uptake velocity of sulfobromophthalein (to 619% of control values) was appreciably greater than the maximal increase in UDP-glucuronyltransferase activity (200% of control) or immunoreactive ligandin concentrations (260% of control) seen in earlier studies, suggesting a direct effect on the plasma membrane transport mechanism.

Comparative atrioventricular node properties after radiofrequency ablation and operative therapy of atrioventricular node reentry

The anatomical substrate for atrioventricular (AV) node reentry is unclear. To gain insights into the mechanism of cure of AV node reentry by nonpharmacological techniques, we compared AV node properties in 53 patients undergoing operative therapy (perinodal dissection) and 43 undergoing radiofrequency ablation (28 posterior approach, 15 anterior approach). Anterior radiofrequency ablation was associated with significant AH prolongation (62 +/- 18 msec vs 136 +/- 64 msec, P < 0.0001), loss of "fast" pathway physiology, and no change in the anterograde refractory period of the AV node (273 +/- 24 msec vs 268 +/- 28 msec, P = NS). Posterior radiofrequency ablation did not change the AH interval (67 +/- 17 msec vs 68 +/- 17 msec, P = NS), prolonged AV node effective refractory period (275 +/- 48 msec vs 320 +/- 55 msec, P < 0.0001), and was associated with loss of "slow pathway" physiology. Operative treatment prolonged the AH interval (66 +/- 18 msec vs 83 +/- 37 msec, P < 0.0001) and the AV node effective refractory period (264 +/- 52 msec vs 364 +/- 112 msec, P < 0.0001), and affected dual pathway physiology inconsistently. These data support the view that the "fast" and "slow" pathways are distinct perinodal entities that can be selectively ablated. The operative approach causes more diffuse and variable injury to the AV node region.

Initiation of atrial fibrillation in the Wolff-Parkinson-White syndrome: the importance of the accessory pathway

Atrial fibrillation in the Wolff-Parkinson-White syndrome may be related to microreentry in the accessory pathway. If such is the case, catheter ablation of the accessory pathway should eliminate atrial fibrillation. Among 95 patients undergoing catheter ablation, 20 had atrial fibrillation during standard electrophysiologic study (atrial vulnerability) before ablation. There were 16 women and four men with a mean age of 32 years. Before ablation six patients required electrical cardioversion. Thirty minutes after ablation, 11 continued to have inducible atrial fibrillation. Atrial fibrillation terminated spontaneously in every patient after ablation. A control group of 20 patients with accessory pathway ablation had no inducible atrial fibrillation before or after ablation. Catheter ablation had no effect on atrial properties including functional refractory period (227 +/- 37 vs 215 +/- 29 msec before versus after ablation, mean +/- SD) or wavelength (7.4 +/- 3.2 vs 7.2 +/- 2.7 before versus after ablation). These data suggest that an intact accessory pathway is not necessary for initiation of atrial fibrillation in most patients with Wolff-Parkinson-White syndrome. A rapid ventricular response over the accessory pathway may facilitate the perpetuation of atrial fibrillation in persons prone to this arrhythmia.

An anatomically guided approach to atrioventricular node slow pathway ablation

Radiofrequency ablation of the "slow" pathway of the atrioventricular (AV) node reentrant circuit may be guided by electrophysiologic ("slow pathway potential") or anatomic landmarks. Experience with a systematic, anatomically guided approach in 25 patients (20 women and 5 men, aged 38 +/- 15 years) with typical AV node reentry is described. The slow pathway is assumed to be the posterior input to the AV node, approaching the nodal region in the corridor between the tricuspid annulus and the orifice of the coronary sinus. A series of radiofrequency lesions are given to interrupt this corridor at its entrance to Koch's triangle. If this is unsuccessful, the series of lesions are repeated progressively at higher levels approaching the AV node. The major end point for success is elimination of the slow pathway as determined by extrastimulus testing. A mean of 1.2 +/- 0.2 ablative sessions (20 +/- 12 applications of energy) achieved clinical success in 24 of 25 patients (96%) at a follow-up of 8.6 +/- 2.2 months. Anterograde Wenckebach cycle length increased from 361 +/- 67 ms to 398 +/- 70 ms (p = 0.01), yet the atrio-Hisian interval in sinus rhythm did not change (69 +/- 17 ms before vs 65 +/- 15 ms after ablation), p = 0.22. Retrograde Wenckebach cycle length was not affected (348 +/- 78 ms before vs 366 +/- 82 ms after ablation). During ablation, transient third-degree AV block occurred in 6 patients with no permanent sequelae. This approach provides a systematic, expedient technique to eliminate slow pathway conduction based on anatomic landmarks.

Coronary thrombolysis with recombinant tissue plasminogen activator. Intracoronary vs intravenous administration

We employed a canine model of coronary thrombosis, induced by injection of radioactive blood clot, via a catheter placed in the left anterior descending coronary artery, to compare effects of recombinant tissue plasminogen activator (rtPA) administered intravenously and administered directly into the coronary circulation. A control group did not receive rtPA. Compared with controls, both rtPA regimens induced coronary thrombolysis. However, compared with intravenous administration, rate and extent of coronary thrombolysis were increased with intracoronary administration. Most likely, the enhanced thrombolysis with intracoronary administration is explained by an increase in delivery of the drug to the thrombus.