Discrete-time predator-prey model with flip bifurcation and chaos control

We explore the local dynamics, flip bifurcation, chaos control and existence of periodic point of the predator-prey model with Allee effect on the prey population in the interior of $\mathbb{R}^*{_+^2}$. Nu-merical simulations not only exhibit our results with the theoretical analysis but also show the complex dynamical behaviors, such as the period-2, 8, 11, 17, 20 and 22 orbits. Further, maximum Lyapunov exponents as well as fractal dimensions are also computed numerically to show the presence of chaotic behavior in the model under consideration.

Genome-wide identification and characterization of the BES1 gene family in apple (Malus domestica)

As the most important transcription factor in the brassinosteroid (BR) signal transduction pathway, BES1 not only affects growth and development of plants but also regulates stress resistance of crops. The physicochemical properties, gene structure, cis-acting elements and gene chip expression of apple BES1 transcription factors were analysed using bioinformatics, and expression of this gene family was analysed with qRT-PCR. There were 22 members of the apple BES1 transcription factors, distributed on eight chromosomes, divided into seven subtribes (I-VII), and the same subtribe contained the same basic motifs. Gene structure analysis showed that the number and position of exons differed, and there was no upstream and downstream structure. Analysis of cis-acting elements indicated that BES1 transcription factors contain response elements for hormones and abiotic stress, as well as organ-specific elements. Gene chip expression profile analysis revealed that expression patterns of BES1 transcription factors differed in different apple hybrids and different organs. In addition, expression of apple BES1 genes was higher in flowers, young fruits, mature fruits and leaves. qRT-PCR demonstrated that expression of MdBES1 genes was highest 12 h after BR induction. At the same time, there were differences in expression in response to PEG, NaCl and MeJA. This paper provides a theoretical basis for analysis of the biological function and stress resistance mechanism of BES1 transcription factors in apple.

New Report of Black Leaf Spot Mold (Pseudocercospora fuligena) on Withania somnifera from India

Withania somnifera (family solanaceae) commonly known as ashwagandha and Indian ginseng, originated in India is one of the most powerful medicinal plants for more than 3,000 years (1). It is commercially cultivated for its roots, a natural rich source of glycowithanolides, tannins, potassium nitrate, etc., which are an anti-inflammatory, anti-tumor, anti-oxidant, anti-ulcer, and regulator of the nervous system and sleep (2). During the monsoon of July 2011, black spots on the leaves of infected plants were observed in the ashwagandha growing Lucknow, Raibareilly, and adjoining areas of Uttar Pradesh province with 10 to 20% disease incidence. Early stage of disease were characterized by the presence of light chlorotic spots on both sides of old leaves that later turned into dark black spots resulting in early defoliation. About 27 samples were collected from different locations of the fields for isolation of the causal organism and microscopic studies. Infected leaves were cut into small pieces, surface sterilized with 1% sodium hypochlorite for 1 min, rinsed thrice with sterilized distilled water, and placed onto potato dextrose agar (PDA) plates. After 21 days of dark incubation at 25°C, 8- to 10-mm grayish-brown colonies were observed. Microscopic studies at early and mature stages of infection showed production of conidia in conidiophores. Conidiophores were mostly 5 to 9, few dense pale brown, simple unbranched, septate, geniculate and 14 to 55 × 3 to 5.5 μm. Conidia were subhyline, obclavate to cylindrical, some were straight to slightly curved, multiseptate, base long obconic to long obconically truncate, and 12 to 85 × 3.5 to 5 μm. On the basis of cultural and morphological studies, the pathogen was identified as Pseudocercospora fuligena (3). The pathogen identity was further confirmed at molecular level using universal primers ITS1/ITS4 through PCR (4). An amplification of the expected size (~550 bp) was generated, eluted from agarose gel by QIAquick gel extraction kit (Qiagen), cloned into pGEM-T Easy vector (Promega), sequenced, and deposited in GenBank (Accession No. KF881898). NCBI BLASTn showed 99% identity with P. fuligena (GU214675) strain CPC 12296, isolated from Lycopersicon sp. Pathogenicity test was carried out on 10 plants of W. somnifera cv. Poshita through two approaches, one using mycelia from culture and another using spore suspension from naturally infected leaves. In the first approach, fungal mycelia were applied onto the healthy ashwagandha leaves, whereas in the second approach, infected leaves were washed with distilled water and spore suspension of 10⁶ spores/ml was sprayed on healthy plants. Plants sprayed with sterilized distilled water served as controls. Inoculated plants were placed in a growth chamber at 28°C under 90% humidity for 3 days. After, pots were placed in the glasshouse at 27 ± 2°C with 70 to 80% humidity for 21 days. Initial symptoms appeared on the 7th day while typical symptoms appeared on all the inoculated plants after 12 to 17 days. Control plants remained free of infection. Re-isolation of the pathogen on PDA fulfilled Koch's postulates. Black leaf mold caused by P. fuligena has been reported on tomato (5). This is the first report of black leaf mould caused by P. fuligena on W. somnifera from India. P. fuligena has the potential to reduce yield of W. somnifera. References: (1) Anonymous. Alt. Med Rev. 9:211, 2004. (2) B. D. Basu and K. R. Kirtikar. Indian Medicinal Plants: Plates, vol. 1-4. Bishen Singh Mahendra Pal Singh, Dehradun, India, 1991. (3) T. C. Wang et al. Plant Dis. 79:661, 1995. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990. (5) S. Yamada. Ann. Phytopathol. Soc. Jpn. 15:13, 1951.

First Report of Wet Rot of Withania somnifera Caused by Choanephora cucurbitarum in India

Withania somnifera (Ashwagandha) is native to India and commercially cultivated for the production of root withanolides that have anticarcinogenic properties. A disease appeared on plantings of W. somnifera during the 2010 monsoon at the CIMAP and in adjoining areas of northern India. Symptoms first appeared as water-soaked lesions on leaves and stems that progressed to a wet rot. Mature lesions harbored black fructifications of the suspect pathogen. Pathogen isolations were done by placing pieces of infected tissues on potato dextrose agar. A fungus tentatively identified as a Choanephora sp. that produced white aerial mycelia that later turned pale yellow was consistently isolated from infected plant parts. Mycelia were hyaline and nonseptate. Sporangiophores bearing sporangiola were erect, hyaline, unbranched, apically dilated to form a clavate vesicle from which arose dichotomously branched distally clavate secondary vesicles. Sporangiola were indehiscent, ellipsoid, brown to dark brown with distinct longitudinal striations, and measured 12 to 20 × 6 to 12 μm. Sporangia were multispored, spherical, initially white to yellow and pale brown to dark brown at maturity, and measured 40 to 160 μm. Sporangiospores from sporangia were ellipsoid to broadly ellipsoid, brown to dark brown, indistinctly striate with fine hyaline polar appendages, and measured 16 to 20 × 8 to 12 μm. On the basis of the cultural as well as morphological characteristics and description in the monograph by Kirk (2), the fungus was identified as a Choanephora sp. The identification was also confirmed by IMTECH, Chandigarh, India with Accession No. MTCC-10731. The species was later characterized as Choanephora cucurbitarum (Berk. & Ravenel) Thaxt (GenBank Accession No. AB470642) by using universal primers ITS-1 and ITS-4. Its sequence comprising of 18S rRNA partial, complete ITS 1, 5.8S rRNA, ITS 2, and 28S rRNA partial was submitted to NCBI GenBank with Accession No. JN639861. Pathogenicity of the fungus was established on five healthy plants by artificial inoculation with spray of an aqueous spore suspension containing 10⁶ spores/ml. Plants sprayed with sterile distilled water were used as controls. Both inoculated and control plants were kept in a humidity chamber (96%) for 3 days and thereafter placed in the glasshouse at 28 ± 2°C. Initial symptoms developed in 2 to 3 days while typical disease symptoms appeared on all the inoculated plants after 7 to 10 days. Control plants were free from infection. The reisolation from artificially infected plants again yielded a Choanephora sp., thus fulfilling Koch's postulates. W. somnifera cultivation has been affected by root rot and wilt caused by Fusarium solani and leaf spot caused by Alternaria dianthicola (3). The occurrence of a Choanephora sp. was reported on periwinkle, petunia (1), and Boerhavia diffusa (4). However, to our knowledge, incidence of this pathogen on W. somnifera has not been reported so far. Thus, wet rot of W. somnifera caused by C. cucurbitarum is a new report from India and worldwide. References: (1) G. E. Holcomb. Plant Dis. 87:751, 2003. (2) P. M. Kirk. Mycol. Pap. 152:1, 1984. (3) C. K. Maiti et al. Plant Dis. 91:467, 2007. (4) N. Singh et al. New Dis. Rep. 23:29, 2011.

Esophageal tuberculosis: role of endoscopic ultrasound in diagnosis

Esophageal involvement by tuberculosis is rare and is commonly secondary to mediastinal lymph nodal involvement. Endoscopic ultrasound (EUS) is a good modality for evaluation of both esophageal wall and mediastinal lymph nodes. The objectives were to study the role of EUS in diagnosing esophageal tuberculosis, to differentiate primary from secondary form, and to assess the response. Retrospective analysis of data over 7 years (i.e. from 2003 to 2009) was used. The study was set in a tertiary care referral institute and focused on patients diagnosed with esophageal tuberculosis. Interventions used included endoscopy, EUS, EUS-FNA (fine needle aspiration) followed by antituberculosis treatment. The main outcome measurements were symptoms, endoscopic features, EUS features, pathological yield, and response to treatment. There were 32 cases of esophageal tuberculosis. The primary symptom was dysphagia, and endoscopy showed ulcers in 18/32 (56.25%) and extrinsic bulge in 20/32 (62.5%) in middle one third of esophagus. EUS showed lymph nodes adjacent to esophageal pathology in all cases. Subcarinal region was the most common site of lymphadenopathy and they were matted, heterogeneous with predominantly hypoechoic center. Histopathology of endoscopic biopsy of ulcers and EUS-FNA of lymph nodes provided the diagnosis of tuberculosis in 27/32 (84.35%). All patients were treated with antitubercular treatment and showed good clinical, endoscopic and endosonographic response. This is a retrospective study, and PCR and culture for Mycobacterium tuberculosis were not done. Esophageal tuberculosis does not appear to be a primary disease and is most likely secondary to mediastinal nodal tuberculosis. A conglomerated mass of heterogeneous with predominantly hypoechoic lymph nodes with intervening hyperechoic strands and foci on EUS appears to be characteristic of mediastinal tuberculosis.

Evidence for resistance to pyrethroids and organophosphates in Plutella xylostella (Lepidoptera: Plutellidae) from Pakistan

The susceptibility of representative pyrethroid (cypermethrin, deltamethrin, lambdacyhalothrin, bifenthrin), organophosphate (chlorpyriphos, triazophos, profenophos) and new chemistry insecticides (spinosad, indoxacarb and emamectin) was investigated for 18 field populations of Plutella xylostella (Linnaeus) from three different zones in Pakistan. The LC(50) (mg ml(-1); 48 h) values of pyrethroids for various populations ranged from 0.19-1.88 for cypermethrin, 0.31-2.64 for deltamethrin, 0.08-1.16 for lambdacyhalothrin and 0.07-0.88 for bifenthrin. The LC(50) (mg ml(-1); 48 h) of organophosphates ranged from 0.52-5.67 for chlorpyriphos, 0.37-4.14 for triazophos and 0.03-2.65 for profenophos. The most probable reason for low toxicity of organophosphates and pyrethroids is the evolution of multiple resistance mechanisms; however, further studies are required to establish these mechanisms. When these same products were tested against a susceptible laboratory population (Lab-Pak), the new chemistry compounds were significantly more toxic than pyrethroids and organophosphates. The results are discussed in relation to integrated pest management and insecticide resistance management strategies for P. xylostella.

Elemental and Nutritional Analysis of Sea Buckthorn (Hippophae rhamnoidesssp.turkestanica) Berries of Pakistani Origin

Sea buckthorn (Hippophae rhamnoides ssp. turkestanica) is a very important medicinal plant in northern areas of Pakistan. The fruit of sea buckthorn is rich in nutrients and medicinal compounds such as vitamins, carotene, flavonoids, essential oil, carbohydrates, organic acids, amino acids, and minerals. In order to compare various populations of sea buckthorn for chemical composition, eight populations from different areas of northern Pakistan were compared using fruit characteristics. Phytochemical analysis of berries showed vitamin C (250-333 mg/100 g), seed oil (7.69-13.7%), oil in softer pulp (19.2-29.1%), phytosterol content of seed oil (3.3-5.5%), and anthocyanin (0.5-25 mg/L), while the mineral element composition analysis revealed high contents of potassium (140-360 ppm), sodium (20-80 ppm), calcium (70-98 ppm), magnesium (150-240 ppm), iron (40-150 ppm), and phosphorus (110-133 ppm). This study established sea buckthorn berries as a good source of biochemical and mineral elements. The high variation between different populations shows the potential of selecting and breeding of the raw material for various defined purposes.

Break-even analysis revisited: the need to adjust for profitability, the collection rate and autonomous income

This paper modifies traditional break-even analysis and develops a model that reflects the influence of variation in payer mix, the collection rate, profitability and autonomous income on the desired volume alternative. The augmented model indicates that a failure to adjust for uncollectibles and the net surplus results in a systematic understatement of the desired volume alternative. Conversely, a failure to adjust for autonomous income derived from the operation of cafeterias, gift shops or an organization's investment in marketable securities produces an overstatement of the desired volume. In addition, this paper uses Microsoft Excel to develop a spreadsheet that constructs a pro forma income statement, expressed in terms of the contribution margin. The spreadsheet also relies on the percentage of sales or revenue approach to prepare a balance sheet from which indicators of fiscal performance are calculated. Hence, the analysis enables the organization to perform a sensitivity analysis of potential changes in the desired volume, the operating margin, the current ratio, the debt: equity ratio and the amount of cash derived from operations that are associated with expected variation in payer mix, the collection rate, grouped by payer, the net surplus and autonomous income.

Oxygen modulates the release of urokinase and plasminogen activator inhibitor-1 by retinal pigment epithelial cells

The aims of this study were to examine the effect of oxygen, in the presence or absence of exogenous growth factors, on the release of plasminogen activators and plasminogen activator inhibitor-1 by cultured human retinal pigment epithelial cells. Antigen and activity levels of urokinase, tissue plasminogen activator and plasminogen activator inhibitor were measured in conditioned media after cells were exposed to three different oxygen environments: hypoxia, normoxia and hyperoxia. Overall proteolytic balance was determined by zymography. The effects of exogenous basic fibroblast growth factor and transforming growth factor-beta were also examined. it was found that retinal pigment epithelial cells released urokinase, tissue plasminogen activator and plasminogen activator inhibitor in measurable quantities. After 48 h, urokinase levels were highest at normoxia, reaching 7.2ng/10(6) cells (+/-2.0 SEM), whereas plasminogen activator inhibitor 1 levels were highest at hyperoxia, reaching 67.5ng/10(6) cells (+/-3.7 SEM). Tissue plasminogen activator levels were minimal (<0.5ng/10(6) cells) and unaffected by both oxygen and growth factors. Overall proteolytic activity was also greatest at normoxia. Fibroblast growth factor stimulated urokinase production dose-dependently, but plasminogen activator inhibitor only minimally. Transforming growth factor-beta stimulated plasminogen activator inhibitor production dose-dependently but urokinase only at higher concentrations. These results suggest that both oxygen tension and growth factors may interact to modulate the proteolytic properties of the human retinal pigment epithelium.

Regulation of placental vascular endothelial growth factor (VEGF) and placenta growth factor (PIGF) and soluble Flt-1 by oxygen--a review

Morphological studies show poor placental vascular development and an increase in the mitotic index of cytotrophoblast cells in intrauterine growth restriction (IUGR). We hypothesized that the reported relatively high oxygen level in the intervillous space in contact with IUGR placental villi will limit angiogenesis by changes in vascular endothelial growth factor (VEGF) and placenta growth factor (PIGF) expression and function. Western immunoblot analysis demonstrates a diametric expression of PIGF and VEGF proteins throughout pregnancy, with P1GF levels increasing and VEGF levels decreasing, consistent with placental oxygenation. PIGF mRNA and protein is increased in IUGR as compared to gestationally matched normal placentae. Increasing oxygen tension upregulates P1GF protein in term placental villous explants, whereas hypoxia downregulates P1GF and VEGFR-1 (Flt-1) autophosphorylation in term trophoblast choriocarcinoma cell line (BeWo). Levels of soluble Flt-1 (sFlt-1) protein in supernatant of term villous explants were upregulated by 1 per cent hypoxia, whereas hyperoxia (40 per cent) decreased sFlt-1 levels, indicating that under conditions of increasing oxygen tension, PlGF function may remain unopposed. The addition of PlGF-1 to a spontaneously transformed first trimester cytotrophoblast cell line (ED27) stimulated cell proliferation while PlGF-2 had little effect. In contrast, the addition of PlGF-1 had little effect on endothelial cell proliferation while this was inhibited by PIGF-2. Taken together these changes provide a molecular explanation for the observed poor angiogenesis in the pathogenesis of IUGR.

Parasite density and malaria morbidity in the Pakistani Punjab

The relationship between quantitative Plasmodiumfalciparum or P. vivax parasitemia and clinical illness has not been defined in Pakistan or in other areas where malaria transmission is not highly endemic. Standardized questionnaires were given to and physical examinations and parasitologic tests were performed in 8,941 subjects seen in outpatient clinics in 4 villages for 13 consecutive months in the Punjab region of Pakistan. The results, based on multivariable analysis, showed that a clinical diagnosis of malaria, a history of fever, rigors, headache, myalgia, elevated temperature, and a palpable spleen among children were all strongly associated with the presence and density of P. falciparum or P. vivax malaria in a monotonic dose-response fashion. The malaria attributable fraction of a clinical diagnosis of malaria, and the same symptoms and signs also increased with increasing P. falciparum and, to a lesser extent, P. vivax, parasitemia. Unlike in sub-Saharan Africa, clinical illness due to malaria often occurs in the Punjab among adolescents and adults and in patients with parasite densities less than 1,000/microl. Clinical guidelines based upon parasitemia and symptomatology must be adjusted according to the intensity of transmission and be specific for each geographic area.

Hypoxia down-regulates placenta growth factor, whereas fetal growth restriction up-regulates placenta growth factor expression: molecular evidence for "placental hyperoxia" in intrauterine growth restriction

Early placental development occurs in an environment of relative hypoxia. Hypoxia promotes angiogenesis and up-regulates vascular endothelial growth factor (VEGF) expression while it down-regulates placenta growth factor (PIGF) that possess 53% homology with VEGF. Morphological studies show poor placental vascular development and an increase in the mitotic index of cytotrophoblasts in intrauterine growth restriction (IUGR). We hypothesized that the reported relatively high oxygen level in the intervillous space in contact with IUGR placental villi will limit angiogenesis by changes in VEGF and PIGF expression and function. Western immunoblot analysis demonstrates a diametric expression of PIGF and VEGF proteins throughout pregnancy with PIGF levels increasing and VEGF levels decreasing, consistent with placental oxygenation. In IUGR placentae, the ratio of PIGF/GAPDH mRNA was increased by 2.3-fold (p < 0.03) and PIGF protein levels were also increased, (p < 0.05) as compared with gestationally-matched normal placentae. PIGF mRNA and protein were localized to the trophoblast bilayer and villous mesenchyme of the human placenta throughout gestation. In vitro studies demonstrated that increasing oxygen tension (hyperoxia) up-regulated PIGF protein in term placental villous explants, whereas hypoxic culture of a term trophoblast choriocarcinoma cell line (BeWo) down-regulated PIGF mRNA and protein and VEGFR-1 (Flt-1) autophosphorylation. The addition of PIGF-1 to a spontaneously transformed first trimester cytotrophoblast cell line stimulated DNA synthesis while PIGF-2 had little effect. VEGF and PIGF exert their biological actions by means of a common receptor VEGFR-1. In the first trimester trophoblast cells, PIGF-1 increased the association of phosphorylated extracellular signal-related kinase (ERK) with VEGFR-1 immunoprecipitates while both PIGF-1 and PIGF-2 also potentiated endogenous VEGF mediated association of phosphorylated extracellular related kinase (ERK) with VEGFR-2 (KDR). More importantly, the addition of PIGF-1 had little effect while PIGF-2 inhibited cell growth in cultured endothelial cells derived from human umbilical vein. Nitric oxide (NO) is reported to promote angiogenesis and PIGF-2 inhibited the basal release of NO from the first trimester trophoblast. The tissue expression and functional studies support the hypothesis of "placental hyperoxia" in early-onset IUGR because hypoxia down-regulates trophoblast PIGF levels, PIGF expression is increased in IUGR, and PIGF-2 inhibits endothelial cell growth. Taken together, these changes provide a cellular explanation for the observed poor angiogenesis in the pathogenesis of IUGR and show that the two PIGF isoforms may modulate trophoblast and endothelial cell function differently, possibly through potentiation of VEGF mediated activation of VEGF-2.

Increased expression of placenta growth factor in proliferative diabetic retinopathy

Proliferative diabetic retinopathy is thought to be mediated by the hypoxic regulation of angiogenic growth factors, in particular the vascular endothelial growth factor (VEGF) family. The aim of this study was to determine if placental growth factor (PIGF), a recently identified member of the VEGF family, was expressed in diabetic eyes undergoing preretinal neovascularization. Rabbit anti-PIGF antiserum was raised using a 20-amino acid N-terminal sequence to PIGF and did not cross react with VEGF165. Immunohistochemistry was performed on specimens of normal retina (n = 8), diabetic retina in the absence (n = 7) and presence (n = 4) of proliferative retinopathy, scatter laser-treated diabetic retina (n = 7), excised fibrovascular preretinal membranes (n = 12), and nondiabetic fibrocellular epiretinal (n = 7) membranes. PIGF levels were also determined in vitrectomy specimens from patients with either proliferative diabetic retinopathy or macular hole. PIGF immunoreactivity was intensely localized to the endothelial and perivascular regions of newly formed blood vessels of excised fibrovascular preretinal membranes. Intense localization of PIGF protein was also observed in superficial retinal vessels in diabetic retinae adjacent to neovascular preretinal membranes. Localization of PIGF was weak or absent in diabetic retinae that showed no evidence of neovascular proliferation. PIGF protein was also absent in normal retinae, in diabetic retinae that had received extensive treatment with scatter laser photocoagulation, and in nonvascularized epiretinal membranes. PIGF was present in all diabetic vitreous samples (mean 103 pg/ml) but nondetectable in control samples. These results strongly implicate a role for PIGF in the pathogenesis of proliferative diabetic retinopathy.

The effects of growth factors and conditioned media on the proliferation of human corneal epithelial cells and keratocytes

BACKGROUND

As growth factors play an important role in epithelial wound repair, we evaluated the effect of exogenous growth factors in the presence and absence of corneal epithelial and keratocyte conditioned medium on human corneal epithelial cell and keratocyte proliferation.

METHODS

Preconfluent cultures of human corneal epithelial cells or stromal keratocytes were exposed to varying concentrations of EGF, TGF-beta or bFGF in the presence or absence of human corneal epithelial or stromal keratocyte conditioned medium. Cell numbers were determined after 48 h incubation. RIA and ELISA were used to quantify the levels of EGF, TGF-beta and bFGF in conditioned media.

RESULTS

EGF and bFGF increased, while TGF-beta decreased, the proliferation of both cell types in a dose-dependent manner. Epithelial cell conditioned medium inhibited, and keratocyte conditioned medium stimulated, the proliferation of both cell types. The proliferative effects of EGF, TGF-beta and bFGF in the presence of keratocyte conditioned medium were additive for both cell types. By contrast, the addition of exogenous growth factors was unable to overcome the inhibitory potential of epithelial conditioned medium. Both conditioned media contained significant levels of bFGF, but TGF-beta levels in epithelial conditioned medium were up to 5 times greater than that in keratocyte conditioned medium.

CONCLUSIONS

The results indicate that corneal cells maintain tissue homeostasis and modulate the wound healing response via paracrine/autocrine pathways.

Intravitreal growth factors in proliferative diabetic retinopathy: correlation with neovascular activity and glycaemic management

AIM

Many growth factors are implicated in proliferative diabetic retinopathy (PDR). It was decided to test the hypothesis that no one factor is predominant but that a regular profile of levels of different growth factors might be operating, and that the profile might differ according to whether or not insulin therapy was part of the patient's glycaemic management. The levels of several growth factors in vitrectomy samples were therefore determined from diabetic patients with tractional, non-haemorrhagic sequelae of PDR and these levels were correlated with (a) each other (growth factor profile), (b) neovascular activity, and (c) the method of glycaemic management (insulin treated (IT) or non-insulin treated (NIT)).

METHODS

72 samples of vitreous were obtained from either diabetic patients with PDR (n = 51) or non-diabetic (control) patients (n = 21). Levels of bFGF, IGF-I, EGF, and insulin were determined by radioimmunoassay; levels of TGF-beta 2 by ELISA; and levels of IGF-I binding protein by western ligand blotting. The data were analysed using appropriate statistics.

RESULTS

There was no regular growth factor profile. bFGF levels were significantly greater in vitreous from NIT patients compared with IT patients and controls. The highest levels of bFGF were found in NIT patients with actively vascularised membranes. TGF-beta 2 levels were significantly greater in vitreous from IT patients compared with NIT patients and controls The highest levels of TGF-beta 2 were found in IT patients with actively vascularised membranes. IGF-I levels were significantly greater in diabetics (irrespective of insulin treatment) than non-diabetics and the highest levels of IGF-I were found in IT patients with actively vascularised membranes. A 34 kDa IGFBP was the predominant IGFBP identified in vitreous and was found to be elevated in diabetics patients.

CONCLUSION

In PDR there is a correlation between intravitreal growth factor levels and both disease state (whether active or fibrotic) and method of glycaemic management.

The effect of scatter laser photocoagulation on intravitreal levels of growth factors in the miniature pig

PURPOSE

To characterise changes in intravitreal growth factor profiles following retinal photocoagulation in the miniature pig.

METHODS

Miniature pig eyes underwent scatter photocoagulation by either diode infrared or emerald green laser. Animals were sacrificed at various times (up to 42 days) post-laser. The eyes were than removed and vitreous samples analysed for basic fibroblast growth factor, insulin-like growth factor-I and epidermal growth factor by radioimmunoassay, transforming growth factor-beta 2 by ELISA and insulin-like growth factor binding proteins using Western ligand blotting.

RESULTS

Vitreous transforming growth factor-beta 2 levels were decreased at 1 h post diode laser and at 4 and 7 days post emerald laser but returned to normal by 21 and 42 days respectively. Vitreous insulin-like growth factor-I levels increased at 4 and 7 days post diode and emerald laser respectively but returned to normal by 21 days. Insulin-like growth factor Western ligand blotting demonstrated that a 34 kDa insulin-like growth factor binding protein was predominant in the pig vitreous; the levels of this binding protein followed an identical trend to those observed for insulin-like growth factor-I. No changes in vitreous levels of either basic fibroblast growth factor or epidermal growth factor were observed following laser treatment.

CONCLUSIONS

Our results demonstrate a significant shift in the balance of intravitreal growth factors following retinal laser photocoagulation. Such changes may be pertinent to the regression of preretinal new vessels after laser photocoagulation.

Oxygen modulates the response of the retinal pigment epithelium to basic fibroblast growth factor and epidermal growth factor by receptor regulation

PURPOSE

To determine if low oxygen affects growth factor responsiveness in retinal pigment epithelial (RPE) cells and if such effects are mediated through changes in cell surface receptors.

METHODS

Proliferating human RPE cells were exposed to varying concentrations of exogenous basic fibroblast growth factor (bFGF) or epidermal growth factor (EGF) at different media oxygen tensions (16 to 147 mm Hg) and cell counts determined after 4 days. Receptor expression was determined by affinity cross-linking and saturation binding studies on confluent RPE cultures exposed to varying media oxygen tensions for 2 days.

RESULTS

Retinal pigment epithelial cells exhibited a greater proliferative response to exogenous growth factors at hypoxia than at higher media oxygen tensions, and they expressed bFGF and demonstrated that hypoxia caused both an increase in the number of EGF receptors per cell and a shift from low to high affinity receptors.

CONCLUSIONS

These results suggest that hypoxia not only can stimulate RPE cell proliferation per se, it also can "prime" cells t respond more markedly to exogenous growth factors. These observations may be important in elucidating the cause of proliferative vitreoretinopathy.

Localisation of placenta growth factor (PIGF) in human term placenta

Placenta growth factor (PlGF) is a growth factor which belongs to the vascular endothelial growth factor (VEGF) family and is known to bind to the fms-like tyrosine kinase receptor (flt-1). Using Western blot analysis a 50 kDa band was identified in placental protein extract which corresponded to PlGF homodimer. Immunoreactive PlGF was localised to the vasculosyncytial membrane and in the media of large blood vessels of the placental villi, while staining within the mesenchyme was weak and diffuse. There was moderate staining for PlGF in discrete cells in the chorion and no staining in the epithelial layer of the amnion. The maternal decidual cells showed strong staining for PlGF immunoreactive protein. PlGF mRNA was predominantly expressed by the vasculosyncytial membrane of villous trophoblast, whilst there was no apparent expression of PlGF mRNA within the villous mesenchyme. These results suggest that PlGF may be an important paracrine factor for vascular endothelial cells in placental angiogenesis and an autocrine mediator of trophoblast function.

Hypoxia induces HSP 70 gene expression in human hepatoma (HEP G2) cells

Populations of cells within solid tumours are exposed to low oxygen concentrations. The mechanism by which tumour cells tolerate such hypoxia is unknown but it may parallel responses to other types of cellular stress. We investigated the effect of oxygen on steady state levels of inducible heat shock protein 70 mRNA in cultured human hepatoma cells. Northern blot analysis demonstrated that hypoxia increased HSP 70 mRNA levels within 3 hours, with a transient 12-fold increase at 6 hours compared with normoxia. We also showed that heat shock induced a 20-fold increase in HSP 70 mRNA. This data suggests that HSPs may be important in tumour progression by protecting cells from hypoxic stress.

Oxygen modulates production of bFGF and TGF-beta by retinal cells in vitro

Vasoproliferative retinopathies result from retinal capillary non-perfusion and consequent inner retinal hypoxia. However, it is not known whether oxygen mediates vasoproliferation directly (at the nuclear level) or indirectly by regulating the production of growth factors. We have investigated the effect of oxygen on the production of basic fibroblast growth factor and transforming-growth-factor-beta by a variety of retinal cell types in culture. Confluent cultures were maintained for 48 hr under varying oxygen tensions ranging from 135 to 18 mmHg. A reduction in basic fibroblast growth factor levels was observed in the cell lysates and extracellular matrix from retinal microvascular endothelial cell, retinal microvascular pericyte and retinal pigment epithelial cell cultures when the oxygen tension of the medium was reduced from 135 to 18 mmHg. Levels of basic fibroblast growth factor in conditioned media from microvascular endothelial and retinal pigment epithelial cell cultures also decreased when the oxygen tension of the medium was reduced from 135 to 18 mmHg. Total transforming-growth-factor-beta (and specifically isoforms 1 and 2) in the conditioned media from all three cell types was similarly modulated by oxygen i.e. it decreased as the oxygen tension of the medium was reduced from 135 to 18 mmHg. In contrast, the steady state messenger RNA levels for both basic fibroblast growth factor and transforming-growth-factor-beta 1 genes in RPE cells increased significantly when the oxygen tension of the medium was reduced from 135 to 18 mmHg. These results support the putative role of oxygen in influencing the balance of growth factors during the development of preretinal new vessels.

Oxygen regulation of TGF-beta 1 mRNA in human hepatoma (Hep G2) cells

Solid tumours comprise populations of cells whose behaviour is thought to be influenced by growth factors and the local oxygen environment. We investigated the effect of oxygen on steady state levels of transforming growth factor-beta 1 mRNA in cultured human hepatoma cells. Northern blot analysis demonstrated that hypoxia mediated an early and sustained induction of TGF-beta 1 mRNA above that seen at higher oxygen tensions. The data suggests that modulation of TGF-beta 1 expression by the local oxygen environment may be important in tumour development and progression.

Effect of varying oxygen concentrations on the proliferation of retinal microvascular cells in vitro

Microvascular fragments and pure cultures of either retinal microvascular endothelial cells, retinal pericytes or Tenon's capsule fibroblasts were grown on a gas permeable substrate while exposed to varying oxygen concentrations (5, 10, 20, 40 and 95% oxygen). For all three cell types cell proliferation was greatest under the lowest oxygen concentration and decreased as the oxygen concentration increased. The decrease in the proliferative ability of cells exposed to the higher oxygen concentrations could be reversed if the cells were returned to a normoxic environment. Endothelial cells were the most sensitive to changes in oxygen tensions showing a proliferative response after 24 hr exposure as opposed to 48 hr for pericytes and fibroblasts. These results suggest a direct mechanism by which the intra-vitreal and intra-retinal oxygen tension may influence both the development of preretinal new vessels (in response to retinal ischaemia) and also the regression of neovascularization following scatter photocoagulation or vitrectomy.

Deficiency of mature B and T lymphocyte subsets in the blood of non-Hodgkin lymphoma patients

The expression of mature B-cell markers and T markers was determined in lymphocytes isolated from the peripheral blood (PBL) of 20 healthy and 51 patients with non-Hodgkin malignant lymphoma (NHL). The disease was classified as newly diagnosed, in remission, or being treated with chemotherapy and of low-, intermediate-, or high-grade malignancy. To avoid technical problems associated with artifacts involving cytophilic immunoglobulins (Ig), we defined mature B-cells by means of three criteria: a) expression of high surface density of Ig sufficient to allow polar movement of receptors to form a cap in an indirect immunofluorescence (IF) assay, b) expression of high density of the human leukocyte antigens DR (HLA-DR) under capped conditions, and c) expression of a 41H.16 marker exclusive to surface Ig+ B-cells. Percentages of PBL able to cap surface Ig (sIg) (lambda, K), HLA-DR (7H.3), and 41H.16 markers were significantly reduced (p less than 0.001) in all of the patients, regardless of treatment status, and the numbers of sIg+-capping cells were similarly reduced in the patients, regardless of the grade of malignancy. Studies with ring fluorescence showed mean percentages of cells expressing OKT3 and OKT4 determinants significantly reduced (P less than 0.001) but OKT8+ cells not significantly different from control. The OKT4/OKT8 ratio was reduced in all patients and did not differ significantly in relation to the degree of malignancy. We conclude that, in NHL, essentially all patients have severe abnormalities in the number of B- or T-cells needed for normal immune responses.

Single-strand breaks or alkali-sensitive sites in the DNA of human myeloma plasma cells and chronic lymphocytic leukemia lymphocytes

Alkaline-elution studies showed significant levels of either DNA single-strand breaks or alkali-sensitive sites in the plasma cells of six out of six myeloma patients and in the lymphocytes of two out of four patients with chronic lymphocytic leukemia as compared with normal human lymphocytes. The increased rate of DNA elution was variable from sample to sample with a range that would correspond to that observed with 100-1000 rad (1 rad = 10 mGy) of X-ray irradiation. This alteration in DNA structure was observed in both new and advanced patients, did not appear to be related to prior therapy, and did not affect the in vitro viability of these cells. Repetitive alkaline-elution profiles obtained with tumor cells from three patients were similar on subsequent samples obtained 1 month apart. Altered DNA elution was not evident in peripheral blood lymphocytes from myeloma patients with altered plasma cell DNA elution. These observations are interesting in light of the recent hypothesis that breaking and rejoining of DNA, regulated by poly(ADP-ribosyl)ation, may be a general mechanism of altering gene expression during differentiation.

Infrared spectroscopic studies of renal stones

The chemical composition of 125 urinary stones was determined by means of an infrared spectrophotometric method using the potassium bromide pellet technique. Statistical combinations regarding the chemical composition of the stones are discussed and compared with the findings of other workers. Calcium oxalate was the commonest component of pure as well as mixed stones.

Keratoplasty and intraocular lenses: current status

Present methods of treating combined corneal disease and cataracts in elderly patients are unsatisfactory, and multiple operative procedures may be required. From 1975 through 1978, 60 attempts were made to restore relatively normal optics and achieve rapid visual recovery with a single operative procedure consisting of keratoplasty, cataract extraction, and intraocular lens insertion in various combinations. As of this writing, there have been few complications, and 82% of the grafts are clear.

Pharmacology and toxicology of alpha-2'-deoxythioguanosine in cancer patients

alpha-2'-Deoxythioguanosine (alpha-TGdR) was administered as a single dose to 13 cancer patients in 18 experiments at dose levels of 150--1500 mg/m2 and as a daily dose to 22 patients in 42 experiments at dose levels of 100--4000 mg/m2/day X 5 days. No significant toxicity was observed. Blood levels and rates of excretion were determined with radiosulfur-labeled alpha-TGdR. Approximately 80% of the dose was excreted in the urine in 24 hours, initially as unchanged alpha-TGdR and increasingly as metabolites. Metabolites appear to be nucleosides and do not include 6-thioguanine, 6-thioxanthine, or 6-thiouric acid to any measurable extent. Small amounts of the alpha-TGdR in blood samples were bound to albumin and to erythrocyte membranes. Blood plasma levels of alpha-TGdR at the highest doses were in the range of 200--300 micrometer, declining in 24 hours to 67--124 micrometer.

Keratoplasty and intraocular lenses: follow-up study

In an effort of explore new approaches with the possibility of improving on existing methods of managing problem cases with combined corneal disease and cataracts, 35 patients were treated by keratoplasty, cataract extraction, and intraocular lens implantation in various combinations or by cataract extraction and lens implantation without keratoplasty over the past two years. Twenty-four of twenty-six grafts have remained clear over a 3- to 21-month period of observation. The two failures have been successfully regrafted. Eleven patients received a penetrating keratoplasty, cataract extraction and intraocular lens with ten remaining clear. Eight patients with corneal disease and aphakia received a penetrating graft and intraocular lens with all grafts remaining clear. Seven patients with a clear graft received a subsequent cataract extraction and lens implantation with six remaining clear. Nine patients with endothelial dystrophy and cataracts were not affected by cataract extraction and lens implantation. The relatively high success rate, rapid visual rehabilitation, and reduction in the incidence of vitreous loss, vitrectomy, and delayed vitreous complications via the methods employed have, to date, proven encouraging. Caution is advised until data from a larger case series and long-term follow-up become available. Short-term success is directly related to technique. To achieve immediate success, the need for considerable experience in keratoplasty and lens implantation can not be overemphasized.

Anorectal and perianal complications of hematologic malignant neoplasms

Among 17 adults with hematologic malignant neoplasms in whom anorectal complications developed, the overall mortality was 53%; for those in whom the disease was not in remission the mortality was 69%, compared with zero for patients who were in remission. All but one of the deaths were directly attributable to septicemia secondary to the anorectal lesion. Over half of the patients had a history of previous anorectal problems or disordered bowel pattern preceding the anorectal complication. The anorectal lesions affecting these 17 patients included prolapsed hemorrhoids (in 5); discrete ulcers in the anal canal and surrounding cellulitis (8); necrosis of the anus and perianal area (2); and perirectal abscesses (2). Only the abscesses responded to surgical drainage. Treatment of the other lesions was conservative: bowel function was maintained as normal as possible, good perineal hygiene was practised and stool softeners were used, while efforts were directed towards achieving remission of the hematologic neoplastic disease.

9-beta-D-arabinofuranosyladenine 5'-phosphate metabolism and excretion in humans

9-beta-D-Arabinofuranosyladenine (ara-A) was converted chemically to the 9-beta-D-arabinofuranosyladenine 5'-phosphate (ara-A-5'-P) and administered i.v. to four cancer patients in seven experiments. Urinary excretion and plasma levels of radioactivity were monitored for 24 hr in each case. Radioactivity present as unchanged ara-A-5'-P, ara-A, and the deamination product of ara-A, 9-beta-D-arabinofuranosylhypoxanthine, was determined. Excretion was, as in earlier studies with ara-A, given i.v., largely as 6-beta-D-arabinofuranosylhypoxanthine. However, in contrast to the 88 to 97% excretion of ara-A and products in 24 hr when ara-A was given by i.v. push, excretion was 41.47 to 79.1% in 24 hr when ara-A-5'-P was given. With the exception of one experiment at a low dose, where plasma ara-A levels were significant for 6 hr, the plasma levels of ara-A were sustained at significant levels for 24 hr after a single dose of ara-A-5'-P. The doses of ara-A-5'-P given were well tolerated by the four patients. Indications are that this derivative provides important advantages (solubility and sustained blood levels) over ara-A.