Metabolic engineering of the anthocyanin biosynthetic pathway in Artemisia annua and relation to the expression of the artemisinin biosynthetic pathway

Four types of cells were engineered from Artemisia annua to produce approximately 17 anthocyanins, four of which were elucidated structurally. All of them expressed the artemisinin pathway. Artemisia annua is the only medicinal crop to produce artemisinin for the treatment of malignant malaria. Unfortunately, hundreds of thousands of people still lose their life every year due to the lack of sufficient artemisinin. Artemisinin is considered to result from the spontaneous autoxidation of dihydroartemisinic acid in the presence of reactive oxygen species (ROS) in an oxidative condition of glandular trichomes (GTs); however, whether increasing antioxidative compounds can inhibit artemisinin biosynthesis in plant cells is unknown. Anthocyanins are potent antioxidants that can remove ROS in plant cells. To date, no anthocyanins have been structurally elucidated from A. annua. In this study, we had two goals: (1) to engineer anthocyanins in A. annua cells and (2) to understand the artemisinin biosynthesis in anthocyanin-producing cells. Arabidopsis Production of Anthocyanin Pigment 1 was used to engineer four types of transgenic anthocyanin-producing A. annua (TAPA1-4) cells. Three wild-type cell types were developed as controls. TAPA1 cells produced the highest contents of total anthocyanins. LC-MS analysis detected 17 anthocyanin or anthocyanidin compounds. Crystallization, LC/MS/MS, and NMR analyses identified cyanidin, pelargonidin, one cyanin, and one pelargonin. An integrative analysis characterized that four types of TAPA cells expressed the artemisinin pathway and TAPA1 cells produced the highest artemisinin and artemisinic acid. The contents of arteannuin B were similar in seven cell types. These data showed that the engineering of anthocyanins does not eliminate the biosynthesis of artemisinin in cells. These data allow us to propose a new hypothesis that enzymes catalyze the formation of artemisinin from dihydroartemisinic acid in non-GT cells. These findings show a new platform to increase artemisinin production via non-GT cells of A. annua.

Right ventricular longitudinal strain measured using feature-tracking cardiac magnetic resonance is an independent predictor of all cause mortality in patients with severe tricuspid regurgitation

Introduction

Tricuspid regurgitation imposes a volume overload on the right ventricle (RV) that can lead to progressive RV dilation and dysfunction. Overt RV dysfunction is associated with poor prognosis and increased operative risk. Abnormalities of myocardial strain may provide the earliest evidence of ventricular dysfunction. CMR feature-tracking techniques now allow assessment of strain from routine cine-images, without specialized pulse sequences. Whether abnormalities of RV strain measured using CMR feature-tracking have prognostic value in patients with tricuspid regurgitation is unknown

Purpose

To evaluate the prognostic value of CMR feature-tracking derived RV free wall longitudinal strain (RVFWLS) in a large multicenter population of patients with severe tricuspid regurgitation.

Methods

Consecutive patients with severe tricuspid regurgitation undergoing CMR at four US medical centers were included in this study. Feature-tracking RVFWLS was calculated from 4 chamber cine-views (Figure-left panel). The primary endpoint was all-cause death. Cox proportional hazards regression modeling was used to examine the independent association between RVFWLS and death. The incremental prognostic value of RVFWLS was assessed in nested models.

Results

Of the 406 patients in this study,115 died during a median follow-up of 8.8 years. By Kaplan-Meier-analysis, patients with RVFWLS ≥median (−16%) had significantly reduced event free survival compared to those with RVFWLS < median (log-rank p<0.001) (Figure-right panel). By Cox multivariable regression modeling, each 1% worsening in RVFWLS was associated with a 13% increased risk-of-death after adjustement for clinical and imaging risk factors (HR=1.13 per %; p<0.001). Addition of RVFWLS in this model resulted in significant-improvement in the global-chi-square (26 to 65; p<0.0001).

Conclusions

CMR feature-tracking derived RVFWLS is an independent predictor of mortality in patients with severe tricuspid regurgitation, incremental to common clinical and imaging risk factors.

Funding Acknowledgement

Type of funding source: None

3225Global longitudinal strain measured using feature-tracking cardiac magnetic resonance imaging is an independent predictor of all cause mortality in patients with preserved ejection fraction

Introduction

Ejection fraction is the principal measure used clinically to assess cardiac mechanics and provides significant prognostic information. However, echocardiographic strain imaging has shown significant abnormalities of myocardial deformation can be present despite preserved ejection fraction, which maybe associated with adverse prognosis. Cardiac-Magnetic-Resonance (CMR) feature-tracking techniques now allow assessment of strain from routine cine-images, without specialized pulse sequences. Whether abnormalities of strain measured using CMR feature-tracking have prognostic value in patients with preserved ejection fraction is unknown.

Purpose

To evaluate the prognostic value of CMR feature-tracking derived global longitudinal strain (GLS) in a large multicenter population of patients with preserved ejection fraction.

Methods

Consecutive patients with preserved ejection fraction (EF ≥50%) and a clinical indication for CMR at four US medical centers were included in this study. Feature-tracking GLS was calculated from 3 long-axis-cine-views. The primary endpoint was all-cause death. Cox proportional hazards regression modeling was used to examine the independent association between GLS and death. The incremental prognostic value of GLS was assessed in nested models.

Results

Of the 1274 patients in this study, 115 died during a median follow-up of 6.2 years. By Kaplan-Meier analysis, patients with GLS ≥ median (−20%) had significantly reduced event free survival compared to those with GLS < median (log-rank p<0.001) (Figure, top panel). The continuous relationship between GLS and the hazard of death is shown in the cubic spline (Figure, lower panel). By Cox multivariable regression modeling, each 1% worsening in GLS was associated with a 23.6% increased risk-of-death after adjustment for clinical and imaging risk factors (HR=1.236 per %; p<0.001). Addition of GLS in this model resulted in significant-improvement in the global-chi-square (67 to 168; p<0.0001) and Harrel's C-statistic (0.716 to 0.825; p<0.0001).

Conclusions

CMR feature-tracking derived GLS is a powerful independent predictor of mortality in patients with preserved ejection fraction, incremental to common clinical and imaging risk factors.

Artemisinin Biosynthesis in Non-glandular Trichome Cells of Artemisia annua

Artemisinin-based combination therapy (ACT) forms the first line of malaria treatment. However, the yield fluctuation of artemisinin has remained an unsolved problem in meeting the global demand for ACT. This problem is mainly caused by the glandular trichome (GT)-specific biosynthesis of artemisinin in all currently used Artemisia annua cultivars. Here, we report that non-GT cells of self-pollinated inbred A. annua plants can express the artemisinin biosynthetic pathway. Gene expression analysis demonstrated the transcription of six known pathway genes in GT-free leaves and calli of inbred A. annua plants. LC-qTOF-MS/MS analysis showed that these two types of GT-free materials produce artemisinin, artemisinic acid, and arteannuin B. Detailed IR-MALDESI image profiling revealed that these three metabolites and dihydroartemisinin are localized in non-GT cells of leaves of inbred A. annua plants. Moreover, we employed all the above approaches to examine artemisinin biosynthesis in the reported A. annua glandless (gl) mutant. The resulting data demonstrated that leaves of regenerated gl plantlets biosynthesize artemisinin. Collectively, these findings not only add new knowledge leading to a revision of the current dogma of artemisinin biosynthesis in A. annua but also may expedite innovation of novel metabolic engineering approaches for high and stable production of artemisinin in the future.

Evaluation of Digital Image Recognition Methods for Mass Spectrometry Imaging Data Analysis

Analyzing mass spectrometry imaging data can be laborious and time consuming, and as the size and complexity of datasets grow, so does the need for robust automated processing methods. We here present a method for comprehensive, semi-targeted discovery of molecular distributions of interest from mass spectrometry imaging data, using widely available image similarity scoring algorithms to rank images by spatial correlation. A fast and powerful batch search method using a MATLAB implementation of structural similarity (SSIM) index scoring with a pre-selected reference distribution is demonstrated for two sample imaging datasets, a plant metabolite study using Artemisia annua leaf, and a drug distribution study using maraviroc-dosed macaque tissue. Graphical Abstract ᅟ.

Overexpression of Artemisia annua Cinnamyl Alcohol Dehydrogenase Increases Lignin and Coumarin and Reduces Artemisinin and Other Sesquiterpenes

Artemisia annua is the only medicinal crop that produces artemisinin for malarial treatment. Herein, we describe the cloning of a cinnamyl alcohol dehydrogenase (AaCAD) from an inbred self-pollinating (SP) A. annua cultivar and its effects on lignin and artemisinin production. A recombinant AaCAD was purified via heterogeneous expression. Enzyme assays showed that the recombinant AaCAD converted p-coumaryl, coniferyl, and sinapyl aldehydes to their corresponding alcohols, which are key intermediates involved in the biosynthesis of lignin. Km, Vmax, and Vmax/Km values were calculated for all three substrates. To characterize its function in planta, AaCAD was overexpressed in SP plants. Quantification using acetyl bromide (AcBr) showed significantly higher lignin contents in transgenics compared with wild-type (WT) plants. Moreover, GC-MS-based profiling revealed a significant increase in coumarin contents in transgenic plants. By contrast, HPLC-MS analysis showed significantly reduced artemisinin contents in transgenics compared with WT plants. Furthermore, GC-MS analysis revealed a decrease in the contents of arteannuin B and six other sesquiterpenes in transgenic plants. Confocal microscopy analysis showed the cytosolic localization of AaCAD. These data demonstrate that AaCAD plays a dual pathway function in the cytosol, in which it positively enhances lignin formation but negatively controls artemisinin formation. Based on these data, crosstalk between these two pathways mediated by AaCAD catalysis is discussed to understand the metabolic control of artemisinin biosynthesis in plants for high production.

Changes in mitotic rate and GFAP expression in the primary olfactory axis of streptozotocin-induced diabetic rats

Many diabetic individuals develop anosmia but the mechanism(s) causing the dysfunction in the olfactory system is (are) unknown. Glial fibrillary acidic protein expression is reduced in diabetic retinopathy and is also reduced, with unknown consequences, in other brain regions of diabetic rats. We used immunohistochemistry and immunoblotting from untreated control and streptozotocin-induced type 1 (insulin dependent) diabetic rats to investigate main olfactory epithelial mitotic rate and glial fibrillary acidic protein expression in the lamina propria of the sensory epithelium and in the olfactory bulb. Numbers of bromodeoxyuridine-positive cells were significantly lower in the diabetic sensory epithelium compared to non-diabetic controls. Immunohistochemical observations suggested a qualitative difference in glial fibrillary acidic protein expression in both regions examined especially in the olfactory bulb external plexiform layer and the lamina propria. Immunoblot analysis confirmed that the diabetic olfactory bulb and lamina propria expressed less glial fibrillary acidic protein compared to the non-diabetic control group. The lower expression levels in the olfactory bulb external plexiform layer suggested by immunohistochemistry do not reflect a change in the number of astrocytes since the numbers of S100B(+) cells were not different between the two groups.

Posttransplantation lymphoproliferative disorder initially seen as iris mass and uveitis

Primary ocular posttransplantation lymphoproliferative disorder is rare. Epstein-Barr virus is implicated as the cause as a result of systemic immunosuppression after transplant surgery. We studied a patient who developed ocular posttransplantation lymphoproliferative disorder after orthotopic liver transplantation. Slitlamp and light microscopic photographs confirmed the diagnosis.

Long-term results of liver transplantation for biliary atresia

BACKGROUND

Biliary atresia can be treated by portoenterostomy, which is primarily palliative, or by liver transplantation, which is primarily curative. The purpose of this study was to determine the long-term outcome of liver transplantation for the treatment of biliary atresia.

METHODS

During an 8-year period, 45 patients who underwent liver transplantation for biliary atresia and 10 patients who were referred to our center for portoenterostomy were retrospectively analyzed.

RESULTS

No patient with biliary atresia died awaiting liver transplantation. The waiting time for all patients was 36.7 +/- 42.8 days. Thirty-four patients (75.6%) required one transplant, whereas 11 patients (24.4%) required 17 retransplants. Twenty-two patients (48.9%) required 39 reoperations (1.8 per patient). There were 4.9 infectious episodes, 2.2 rejection episodes, and 4.4 readmissions per patient. However, 91% of reoperations, 80% of infections, and 78% of rejections occurred within 6 months of transplantation. The overall 7-year actuarial patient and graft survival for patients with biliary atresia was 86.2% and 62.7%, respectively.

CONCLUSIONS

Our results indicate that long-term patient survival after liver transplantation for biliary atresia is excellent. However, portoenterostomy continues to have an initial complementary but limited long-term role in the treatment of infants with biliary atresia.

Utility of immunohistochemistry in distinguishing ovarian sertoli-stromal cell tumors from carcinosarcomas

Poorly differentiated Sertoli-stromal cell tumors and carcinosarcomas of the ovary both show biphasic epithelial and stromal patterns and may both show heterologous stromal elements, presenting a difficult diagnosis. We studied the immunohistochemical profile of Sertoli cell differentiation in human testes and applied these findings to the ovarian tumors. Eleven Sertoli-stromal cell tumors, six carcinosarcomas of the ovary, and 11 testes (six fetal, one infant, and four adult) were studied using antibodies to cytokeratin AE1:AE3 (AE1:3), cytokeratin CAM 5.2 (CAM), epithelial membrane antigen (EMA), vimentin, desmin, muscle-specific actin (MSA), S-100 protein (S-100), CA 19-9, CA 125, carcinoembryonic antigen monoclonal (CEA-M), carcinoembryonic antigen polyclonal (CEA-P), and placental alkaline phosphatase (PLAP). In the fetal testes, immature gonadal stroma and sex cord areas stained with vimentin (six of six cases), AE1:3 (five of six cases), and CAM (six of six cases). Sertoli cells in immature gonadal stroma areas, sex cords, and seminiferous tubules of normal fetal, infant, or adult testes never showed immunoreactivity for EMA, S-100, CA 19-9, CA 125, CEA-M, CEA-P, or PLAP. All Sertoli-stromal cell tumors stained with AE1:3 and CAM in areas of Sertoli cell differentiation (11 of 11 cases) but did not stain with EMA, PLAP, CEA-P, CEA-M, CA 19-9, CA 125, or S-100 (none of 11 cases). Carcinosarcomas expressed AE1:3 and CAM in all epithelial areas (six of six cases) and most stromal areas (five of six cases). Carcinomatous areas of carcinosarcoma also showed immunoreactivity for EMA (six of six cases), CA 125 (two of six cases), PLAP (two of six cases), CEA-P (two of six cases), and CEA-M (one of six cases), while stromal areas of carcinosarcoma expressed EMA (four of six cases) and S-100 (four of six cases). Heterologous stromal elements were present in three of 11 Sertoli-stromal cell tumors (two showed skeletal muscle and one showed both skeletal muscle and cartilage differentiation) and in four of six carcinosarcomas (one skeletal muscle, one cartilage, and two cartilage and skeletal muscle). All skeletal muscle heterologous elements expressed desmin, vimentin, and MSA. The heterologous cartilage in carcinosarcoma stained with S-100 (three of three), while the one case of heterologous cartilage in Sertoli-stromal cell tumor did not. These results suggest that ovarian Sertoli-stromal cell tumor can be distinguished from carcinosarcoma by the absence of staining for EMA, PLAP, CEA, CA 125, or CA 19-9 in epithelial areas of Sertoli-stromal cell tumor.(ABSTRACT TRUNCATED AT 400 WORDS)

Human papillomavirus infection and anal carcinoma. Retrospective analysis by in situ hybridization and the polymerase chain reaction

To examine the association of human papillomavirus (HPV) infection with anal squamous cell carcinoma, the authors applied the highly sensitive polymerase chain reaction (PCR) and in situ hybridization (ISH) techniques to detect HPV DNA in formalin-fixed, paraffin-embedded tissues from 18 patients. The presence of HPV types 16/18 in 3 (16.7%) of 18 patients with anal carcinoma was found, using a colorimetric ISH technique for HPV types 6, 11, 16, 18, 31, 35, and 51. Results from one of these three patients were also positive for HPV 31, 35, 51 by ISH techniques. When the same series was analyzed using the PCR and consensus primers to the L1 open reading frame of the HPV genomes, the frequency of positive patients rose to 14 (77.8%) of 18. PCR analysis of the 14 lesions containing HPV DNA, using type-specific primers and probes for HPV 6, 11, 16, 18, and 33, showed that 1 contained HPV 6, 1 contained HPV 11, 4 contained HPV 16, 1 contained HPV 18, 1 contained HPV 33, 5 contained HPV of unclassified type(s), and 1 contained a mixture of three HPV types. There was concordance between typing of cases that were positive by ISH and PCR methods. These data agree with the concept that HPV, in particular type 16, is implicated in the pathogenesis of anal cancer.

Human papillomavirus type 6 detected by the polymerase chain reaction in invasive sinonasal papillary squamous cell carcinoma

Eight sinonasal carcinomas (one adenocarcinoma, two undifferentiated nasopharyngeal carcinomas, and five squamous cell carcinomas) were investigated for evidence of human papillomavirus (HPV) infection using in situ hybridization and the polymerase chain reaction for HPV types 6, 11, 16, 18, and 33. All eight cases were negative for HPV infection by in situ hybridization, while a single HPV-6-positive case was identified by the polymerase chain reaction. The HPV-positive case was an invasive papillary squamous cell carcinoma of the maxillary sinus. Although HPV-6 is usually associated with benign anogenital condylomata, it has been identified in malignant lesions of the upper respiratory tract. This may reflect exposure of the upper aerodigestive tract to additional carcinogens, such as smoke and alcohol, superimposed on the background proliferative stimulus of the HPV infection.

Glassy cell features in adenosquamous carcinoma of the uterine cervix. Histologic, ultrastructural, immunohistochemical, and clinical findings

Glassy cell features (GCF) were identified as composing a predominant pattern (more than 85% of histology) in six cases and a focal pattern (33-85% of histology) in 10 cases of a series of 53 adenocarcinomas (AC) and adenosquamous carcinomas (ADSQ) of the uterine cervix. In three cases examined ultrastructurally, GCFs correlated with many cytoplasmic polyribosomes and abundant rough endoplasmic reticulum, but Golgi complexes and tonofilaments were scant and intracytoplasmic lumina were absent. Intracellular mucin was present in the areas showing GCFs of four ADSQs with predominant GCFs and six ADSQs with focal GCFs. Two of three cases examined ultrastructurally showed intracellular electron-dense material that corresponded to mucin secretory material. Immunohistochemical studies of the six ADSQs with predominant GCF cases showed the following pattern of reactivity: monoclonal carcinoembryonic antigen (CEA), 2 of 6 cases; polyclonal CEA, 3 of 6; CA 125, 0 of 6; CA 19-9, 0 of 6; placental alkaline phosphatase, 0 of 6; and vimentin, 1 of 6. Focal GCF areas showed monoclonal CEA, 4 of 9 cases; polyclonal CEA, 3 of 9; vimentin, 4 of 9; while CA 125, CA 19-9, and placental alkaline phosphatase were negative in areas of GCFs. One of three patients with ADSQ with predominant GCFs and five of nine patients with ADSQ with focal GCFs with at least 1 year of follow-up were disease free. No association between GCFs (combined focal and predominant) and recurrent disease was present when compared to the other 29 AC and ADSQ patients with follow-up. Recurrent disease in our series of AC and ADSQ was only associated with stage III or IV disease at presentation (P less than 0.001). There was no association with adenosquamous histology, histologic grade, lymphatic invasion, or age. There were insufficient cases of ADSQ with predominant GCFs with follow-up to evaluate fully prognostic significance of this subgroup. Our study suggests that GCFs are part of the spectrum of differentiation in ADSQ of the cervix rather than a distinct histologic type of carcinoma with unique clinical significance.

Advantages of an immunohistochemical estrogen receptor assay

Immunohistochemical and biochemical assays for estrogen and progesterone receptors were done on 20 breast carcinomas, and results were correlated with various histologic features. The slide-based immunohistochemical technique demonstrated several distinct advantages relative to the tissue homogenization required by the traditional biochemical assay. With the use of frozen tissue sections, the immunohistochemical technique permitted direct visualization of antireceptor binding to tumor cells. Receptor staining of reactive stroma, necrotic tumor, and intermingled benign parenchyma was easily distinguished from receptor staining of the actual carcinoma. This separation is not possible with the biochemical assay. In addition, in situ and invasive components and different morphologic subtypes were evaluated independently. Receptor content of the most aggressive portion of the neoplasm is likely to have the greatest clinical relevance and prognostic significance. Careful correlation of histochemical scores with biochemical assay concentrations is needed to permit the application of this technique to patients entering cancer treatment protocols.

Sinonasal papillomas and human papillomavirus: human papillomavirus 11 detected in fungiform Schneiderian papillomas by in situ hybridization and the polymerase chain reaction

A series of 19 paraffin-embedded sinonasal papillomas (four squamous papillomas, three fungiform papillomas, nine inverted papillomas, and three cylindrical cell papillomas) were investigated for evidence of human papillomavirus (HPV) infection using immunohistochemistry (polyclonal antibody to HPV capsid antigen), in situ hybridization (DNA probes for HPV 6/11, 16/18, and 31/33/35), and the polymerase chain reaction (primers and probes for HPV 6, 11, 16, 18, and 33). All three fungiform papillomas were positive by all three techniques: immunohistochemistry, in situ hybridization for HPV 6/11, and the polymerase chain reaction for HPV 11. None of the other lesions contained detectable HPV using the specific probes included in this study. These results support the continued classification of fungiform papilloma as a distinctive variant of schneiderian papilloma characterized by a predominantly exophytic growth pattern and an association with HPV 11.

Carcinoma (malignant mixed müllerian [mesodermal] tumor) of the uterus and ovary. Correlation of clinical, pathologic, and immunohistochemical features in 29 cases

We examined the histologic, immunohistochemical, and clinical features of a series of 23 endometrial, five cervical, and one ovarian carcinosarcomas (malignant mixed müllerian [mesodermal] tumors) and nine associated distant peritoneal metastases. The primary tumors all showed epithelial differentiation (cytokeratin and/or epithelial membrane antigen expression) of the carcinomatous component, while sarcomatous areas showed epithelial differentiation in all but one case. The metastases showed uniform staining for cytokeratin (eight of eight cases) and epithelial membrane antigen (eight of eight cases), including the spindle cell component that was present in four of nine cases. Desmin significantly changed the interpretation of rhabdomyosarcoma differentiation by refuting putative rhabdomyoblasts in two cases and identifying rhabdomyoblasts in two other cases where they were unrecognized on hematoxylineosin staining. S100 protein was positive in all five cases with chondrosarcoma differentiation. Muscle-specific actin and vimentin were positive in the sarcomatous component of all cases and in the carcinomatous component of seven and 10 cases, respectively. After immunostaining, heterologous elements were present in 18 of 29 cases (11 cases of rhabdomyosarcoma, three cases of chondrosarcoma, three cases of mixed rhabdomyosarcoma and chondrosarcoma, and one case of liposarcoma). Only six of 27 patients with follow-up were disease free for 12 months or longer (associated with stage I or II disease, smaller size, no lymphatic invasion in the resection specimen, and no invasion of the outer two thirds of myometrium). Presence and type of heterologous elements, grade of sarcomatous or carcinomatous components, histologic type of carcinomatous component, gross appearance, presence of necrosis, or use of chemotherapy or radiotherapy did not affect outcome. Carcinosarcomas are clinically aggressive distinctive mixed epithelial-stromal neoplasms with histologic and immunohistochemical features that overlap with metaplastic carcinoma in many cases.

Combined true thymic hyperplasia and lymphoid hyperplasia in Graves' disease

True thymic hyperplasia (enlarged gland composed of histologically unremarkable cortical and medullary parenchyma) and lymphoid hyperplasia (medullary lymphoid follicles in the clinical setting of autoimmunity) usually develop as independent pathologic processes. We reviewed the clinical features and gross and microscopic pathology of 2 hyperthyroid patients with features of both thymic hyperplasia and lymphoid hyperplasia. The diagnosis of thymic hyperplasia was supported by thymic weights greater than two standard deviations above the mean weight for age and histologic evidence of expanded cortical and medullary parenchyma. The diagnosis of lymphoid hyperplasia was supported by the increased number and size of medullary lymphoid follicles and the association with Graves' disease. This unusual combination results from two separate pathogenic mechanisms operating simultaneously in hyperthyroid patients. Elevated thyroid hormones directly stimulate the proliferation of thymic epithelium, producing thymic hyperplasia. The immune abnormalities underlying Graves' disease can also result in lymphoid hyperplasia of the thymus.

Multiple arteriovenous malformations of the small intestine in a patient with protein S deficiency

The authors report a case of arteriovenous malformations (AVMs) of the small intestine in a young patient with protein S deficiency. These disorders have not been previously reported to occur together. Protein S deficiency may cause thromboses in unusual sites, including the mesenteric veins. Several mechanisms linking protein S deficiency to the occurrence of AVMs in this patient are offered.

Recurrent Reye-like syndrome: possible association with Krebs cycle abnormality

During a 7-year period, a 15-year-old boy experienced recurrent attacks that clinically and pathologically resembled Reye's syndrome. The attacks were precipitated by prolonged exercise, fasting or infections. An extensive investigation failed to identify a toxic cause or specific metabolic disorder. Low 14CO2 production after in vitro incubation of the patient's liver with 14C-labeled palmitate, citrate and glutamine suggested a defect in the Krebs cycle or the oxidative phosphorylation pathway. This error may be responsible for the recurrent Reye-like syndrome attacks.

Giardiasis in childhood: poor clinical and histological correlations

Ten pediatric patients investigated for chronic diarrhea, chronic weight loss, or failure to thrive were found on intestinal biopsy and/or in a duodenal aspirate to have Giardia lamblia. Serum immunoglobulin levels were normal or elevated in all patients. Three children had increased excretion of fecal fat and three other children had low D-xylose absorption. Jejunal biopsy specimens showed two severe, three moderate, and two mild morphological abnormalities, and three were normal. Except for lactase deficiency, disaccharidase activities correlated poorly with the severity of mucosal damage on biopsy. Steatorrhea was seen only with the more normal biopsies. Immunofluorescent staining of the biopsies for IgG, IgM, IgA, and secretory piece revealed no immune defects. Thus, there was no single malabsorption defect associated with giardiasis, and the specific defects did not necessarily correlate with morphological changes.