A comparison between neural-network forecasting techniques--case study: river flow forecasting.

Estimating the flows of rivers can have significant economic impact, as this can help in agricultural water management and in protection from water shortages and possible flood damage. The first goal of this paper is to apply neural networks to the problem of forecasting the flow of the River Nile in Egypt. The second goal of the paper is to utilize the time series as a benchmark to compare between several neural-network forecasting methods.We compare between four different methods to preprocess the inputs and outputs, including a novel method proposed here based on the discrete Fourier series. We also compare between three different methods for the multistep ahead forecast problem: the direct method, the recursive method, and the recursive method trained using a backpropagation through time scheme. We also include a theoretical comparison between these three methods. The final comparison is between different methods to perform longer horizon forecast, and that includes ways to partition the problem into the several subproblems of forecasting K steps ahead.

Richner-Hanhart's syndrome: new ultrastructural observations on skin lesions of two cases.

New ultrastructural observations are described in skin lesions of two brothers with Richner-Hanhart's syndrome (RHS). Physical examination of the two patients showed painful skin lesions of palms and soles combined with denderitic corneal ulceration and mental retardation. The diagnosis of RHS was confirmed biochemically with high tyrosine levels in both blood and urine. Examination by transmission electron microscopy revealed several abnormal ultrastructural changes in the epidermal cells. The horny cells contained heterogeneously, electron-dense cytoplasm with many lipid droplets. The granular cell cytoplasm contained abundant tonofibrils and keratohyaline granules. The spinous cell cytoplasm was vacuolated due to the presence of minute tyrosine crystals, which are known to have a lytic effect. The surrounding keratinocytes contained multilobed nuclei. The basal epidermal cells appeared normal except for Merkel cells, which were severely damaged by vacuolatio, also due to the presence of tyrosine crystals. This study showed that high tyrosine levels can induce several ultrastructural pathological changes in the epidermal cells, including the skin chemoreceptor Merkel cells.

Human cutaneous leishmaniasis: ultrastructural interactions between the inflammatory cells and Leishman bodies in the skin lesions.

The ultrastructural interactions between the inflammatory infiltrate and Leishman bodies (LBs) were described in skin lesions from 16 patients with acute cutaneous leishmaniasis. In early stages of the inflammation, the cellular infiltrate consisted of both undifferentiated and differentiated (activated) monocytes (M), macrophages (Mc), multinucleated giant cells (MNGC), plasma cells (PC), lymphocytes (Ly), and fibroblasts (F). In late stages, the infiltrate was in the form of tuberculous granulomas consisted mainly of type I secretory, and type II vesicular epithelioid cells (ECs), in addition to remnant of some inflammatory cells seen in the early stages. The two types of ECs were found only in six patients. The activated M, Mc and MNGC were often parasitized by LBs. The parasites were enclosed within the host cell digestive vacuoles (DVs), or phagolysosomes, together with skin melanosomes which are known to have lysosomal effect. In the DVs, LBs either survived or were killed and expelled from the host cell cytoplasm. This study showed, for the first time, that the melanosomes were apparently involved in killing of the LBs possibly by increasing the fatal effects of the DVs hydrolytic enzymes. Plasma cells were packed with large "Russell's bodies" indicating a high cellular immunoglobulin activity. The large, granular lymphocytes were in close contact to the activated M, possibly to promote delivery of activation signals. The type I secretory ECs contained mucin-like granules with electrondense cores. In late stages of inflammation, the type II vesicular ECs contained lysosomal granules, and were found together with the type I ECs in broken-down tuberculous granulomas. The type I secretory ECs were previously thought to produce a mediator, or "granuloma factor" which recruits undifferentiated mononuclear cells to perpetuate the granulomatous process; while the type II vesicular ECs were thought to appear where the granulomatous process in brought to an end, preceeding the healing by fibrosis.

Visceral and cutaneous leishmaniasis comparative ultrastructure of host-parasite interactions.

The comparative ultrastructure of host-parasite interactions is described for the first time in patients with visceral (VL) and cutaneous (CL) leishmaniasis. In patients with VL, the parasite invades the bone marrow (BM) macrophages (Mcs) and neutrophils, while in patients with CL, the parasite invades the dermal fibroblasts in addition to Mcs. The skin Mcs seem to have more lethal effects on the parasite than the BM Mcs; this is possibly due to the presence of numerous melanosomes with acid phosphatase activity in the Mcs digestive vacuole. In patients with high level of VL parasitaemia, the parasite may induce the BM reticulocytes to phagocytose both the parasite and mature erythrocytes, i.e. lost recognition. In patients with low level of VLparasitaemia, the parasite may induce the BM Mcs to be haemophagocytic, i.e. temporarily mimick malignant histiocytosis until the course of treatment. In early stages of CL infection, the cellular infiltrate consists of the monocyte-macrophage system, plasma cells, lymphocytes and fibroblasts; while in the late stages, two types of epithelioid cells (ECs) are added to the infiltrate and are involved in the formation of tuberculous granulomas. Type I ECs thought to produce a granuloma factor, while type II ECs possibly precedes healing by fibrosis. However, the severity of host-parasite interactions seems to depend mainly on species of the parasite, the degree of parasitaemia, the type of infected tissue(s), and the variation of host tissue reaction against the parasite from one patient to another.

Deleterious effects of khat addiction on semen parameters and sperm ultrastructure.

The semen parameters and sperm ultrastructural morphology have been described in semen samples from two groups of Yemeni subjects. The first 'exposed' group comprised 65 khat addicts, while the second control group included 50 non-khat addict subjects. The mean age was 39.94 +/- 13.85 and 35.72 +/- 11.35 years in the exposed and control groups respectively, without a significant difference. The mean duration of khat addiction among the addicts was 25.34 +/- 12.96 years (range 6.00-48.00). Statistically significant differences were detected between the semen parameters of the two groups. Such parameters, including semen volume, sperm count, sperm motility, motility index and percentage of normal spermatozoa, were lower among addicts. Significant negative correlation was also found between the duration of khat consumption and all semen parameters (r ranged from -0.30 to -0.74). At the transmission electron microscopy level, a counting system was incorporated to compare the numbers of normal spermatozoa with deformed and dead spermatozoa in ultrathin plastic sections. The total mean percentage of deformed spermatozoa was approximately 65%. Different patterns of sperm deformation were demonstrated, and included both the head and flagella in complete spermatozoa, aflagellate heads, headless flagella and multiple heads and flagella. Deformed heads showed aberrated nuclei with immature nuclear chromatin and polymorphic intranuclear inclusions; these were associated with acrosomal defects. The deformed flagella demonstrated numeric aberrations of the axonemal 9 + 2 configuration and structural defects of their associated elements. Persistent cytoplasmic droplets were observed frequently. This study has shown for the first time the deleterious effects of khat addiction on semen parameters in general and sperm morphology in particular of all addicts, especially those who have consumed khat for longer periods of time.

Human bilharzial ureters: I. Fine structure of eggs deposited in the submucosa and muscularis.

The internal fine structure of the partially calcified Schistosoma haematobium eggs in the lower ureteral segments of Saudi patients with chronic urinary schistosomiasis is described. The egg shell is penetrated by cribriform pores and consists of the three previously described layers: outer microspinous, middle intermediately dense, and inner dense layers. The space between the egg shell and the developing embryo is partitioned by three layers. An outer acellular Reynolds' layer of unknown origin and function consists of a fribrillar material mixed with a finely granular matrix extending to the egg-shell pores via racemose channels. The middle von Lichtenberg's envelope consists of a single layer of flattened epithelial cells containing several mitochondria as in other previously described Schistosoma eggs suggesting an active, and perhaps selective, transport in or out of the egg shell. The inner fluid filled cavity, or Lehman's lacuna, between the von Lichtenberg's envelope and the embryo contains numerous lipoid bodies suggesting a relation to vitelline cells. Four systems (out of eight previously described for the free, mature Schistosoma miracidium) have been recognized for the first time in the developing miracidium within S. haematobium eggs and include: (1) ciliated epidermal plates representing the epithelial system, (2) an outer circular and an inner longitudinal muscle layer forming the musculatures, (3) lateral penetration glands, and (4) ciliated flame cells representing the excretory system.

Helicobacter pylori: I. Ultrastructural sequences of adherence, attachment, and penetration into the gastric mucosa.

New ultrastructural observations on the sequences of adherence, attachment, and penetration of Helicobacter pylori (HP) into the gastric epithelium were described in 32 endoscopic biopsies selected randomly from 168 samples of patients with active chronic gastritis. The adherence of HP to the target cell was initiated by direct contact with the microvillar coat, or glycocalyx, leading to the loss of that coat. The next step was demolishing of the surface microvilli, which separate the organisms from the cell cytoplasmic apices containing the main target of the HP, the mucoid granules. Thus the organisms come into close contact with the uncoated cell membrane and are ready for firm attachment. The attachment process was enhanced by the appearance of HP fibrillarlike strands (FLS). Up to three sites of attachment were recognized for individual organisms. Penetration into the apical cytoplasmic regions occurred by one of the organism's poles without damaging the host cell membrane. While a cell is being penetrated by one pole, FLS may extend from the other free pole to be in direct contact with the limiting membranes of the neighboring cell mucoid granules. Penetration into the gastric cells by a great number of organisms leads to serious cell damage and ultimately to cell disintegration. As a response, many neutrophils were found penetrating into the base of the gastric glands from the surrounding lamina propria; these cells were found damaged and disintegrated in the gland lumena. The neutrophils were absolutely HP-nonphagocytic. This study suggests that the dynamic activity of HP in the gastric epithelium and the possible release of the neutrophil granular contents in the gastric lumena play important roles in the gastric lesions during active chronic gastritis.

Human bilharzial ureters: I. Fine structure of eggs deposited in the submucosa and muscularis.

The internal fine structure of the partially calcified Schistosoma haematobium eggs in the lower ureteral segments of Saudi patients with chronic urinary schistosomiasis is described. The egg shell is penetrated by cribriform pores and consists of the three previously described layers: outer microspinous, middle intermediately dense, and inner dense layers. The space between the egg shell and the developing embryo is partitioned by three layers. An outer acellular Reynolds' layer of unknown origin and function consists of a fibrillar material mixed with a finely granular matrix extending to the egg-shell pores via racimose channels. The middle von Lichtenberg's envelope consists of a single layer of flattened epithelial cells containing several mitochondria in other previously described Schistosoma eggs suggesting an active, and perhaps selective, transport in or out of the egg shell. The inner fluid filled cavity, or Lehman's lacuna, between the von Lichtenberg's envelope and the embryo contains numerous lipoid bodies suggesting a relation to vitelline cells. - Four systems (out of eight previously described for the free, mature Schistosoma miracidium) have been recognized for the first time in the developing miracidium within S. haematobium eggs and include: 1) ciliated epidermal plates representing the epithelial system, 2) an outer circular and an inner longitudinal muscle layers forming the musculatures, 3) lateral penetration glands, and 4) ciliated flame cells representing the excretory system.

Human bilharzial ureters: IV. Ultrastructural interaction between multinucleate giant cells and the parasite eggs.

The ultrastructural interaction between multinucleate giant cells (MGCs) and the Schistosoma haematobium eggs is described at the transmission electron microscopy (TEM) level, in granulomas of the lower ureteral segments of Saudi patients. The MGCs were found only within the parasite empty egg-shells which were embedded in the ureter submucosa and muscularis. For the first time, two morphologically different types of MGCs were recognized: the moderate to electron-dense type I contained two types of 8-12 nuclei and cytoplasm poor in cell organelles which appeared non-functional. Type 1 MGCs were considered to be "old" and non-active cells. The electron-lucent to moderately dense type II MGCs contained 3-4 nuclei of one type, and cytoplasm rich in cell organelles. According to the performance of their organelles, type II MGCs were considered to be "young" and highly active cells. The human type II MGCs did not form the cytoplasmic membranous labyrinths previously described for the free moving MGCs obtained from experimental mice, and were suggested to be involved in the cell motility. As in murine MGCs, type II cells were incorporated in exocytic and endocytic activities aimed the degradation of the inner soft layer of the egg-shell. This study shows that individual macrophages were responsible for eliminating the outer and possibly the middle hard layers of the egg-shell.

Falciparum malaria in naturally infected human patients: VIII. Fine structure of intraerythrocytic asexual forms before and during chloroquine treatment.

The fine structure of the intraerythrocytic asexual forms of Plasmodium falciparum is described before and during treatment with chloroquine (CQ) in the venous blood of 27 Saudi patients whe were heavily infected with the parasite. Before treatment, the "pear" shaped merozoite was rapidly transformed into a ring-shaped trophozoite. This was enclosed in a parasitophorous vacuole bounded by a single membrane derived from the host erythrocyte. The parasite feeding mechanism involves several previously undescribed endocytic organelles that function to internalize the erythrocyte haemoglobin into the central food vacuole (FV). Crystalline pigment particles, the trophozoite final metabolic product, accumulated in residual membrane-bound vacuoles. Fully mature schizonts releasing newly produced merozoites were seen for the first time at the electron microscopy level. During treatment, the parasite cytoplasm appeared divided into a vacuolated, electron-dense, ribosomal region and a less dense FV. The feeding mechanism was apparently inhibited; this was indicated by severe damage to the FV and absence of the endocytic organelles, seen in the healthy parasite, causing its starvation and death.

Falciparum malaria in naturally infected human patients: X. Ultrastructural pathological alterations of renal glomeruli.

The ultrastructural pathological alteration of the renal glomeruli is described in nine patients with acute Plasmodium falciparum infection. Glomeruli were large and hypercellular with various types of blood cells in their capillary lumena. These were occasionally occluded with enlarged endothelial cells. Epithelial cells, or podocytes, were hypertrophied with extensively diffused foot processes fusion and numerous villous transformation, or appeared cedemalous filling the urinary space. The glomeruli basement membrane was irregular in thickness or focally missing. Mesangial cells were undergoing proliferation and contained electron-dense deposits. Subendothelial, "hump"-like deposits, similar to those previously described in immune complex nephritis, were detected in most cases; but the largest amount was found in the three youngest patients in whom parasitaemia levels were the highest. This study showed that the kidney may become the target damage mediated by immunopathologic mechanism, and the developed lesions may correspond, for certain extent, to membranoproliferative glomerulonephritis with abnormal deposits, during the acute infection with falciparum malaria. The amount and density of the immune complex deposit could be correlated with the degree of parasitaemia and, in return with the degree of glomerular immunopathological alterations.

Visceral leishmaniasis: III. Effect of parasitaemia level on the bone marrow ultrastructure.

The ultrastructure of bone marrow (BM) aspirates was studied in two patients with visceral leishmaniasis (VL), or Kala-azar. The parasitaemia was remarkably high in the first patient, while it was very low in the other. The BM of the second patient was mimicking malignant histiocytosis (MH). In both patients, the BM were hypercellular with active tri-lineage haemopoiesis, and there was a marked increase of haemophagocytic histiocytes in the second patient. Leishman-Donovan bodies (LDB) were found within BM macrophages & neutrophil granulocytes, and were trapped by monocyte filopodia-like extensions. Transmission electron microscopy (TEM) revealed structural abnormalities in the various cell types including erythroblasts, eosinophils, plasma cells, megakaryocytes and mega-thrombocytes. A counting system was incorporated to determine the rate of abnormal to normal cells in plastic sections. This study showed that there is no significant correlation between the degree of parasitaemia and both the rate and structural abnormalities of BM cells in patients with Kala-azar; erythroblasts have the highest rate of abnormal to normal cells and could be related to anaemia associated with VL; and Kala-azar may have independent effects on the BM.

Human bilharzial ureters: III. Fine structure of the egg granuloma.

The fine structure of egg granuloma forming cells is described in lower ureteral segments of patients chronically infected with Schistosoma haematobium. The infiltrates consisted of monocytes, macrophages, lymphocytes, plasma cells, neutrophils, eosinophils, fibroblasts, mast cells, and blood platelets. The abundant monocytes and macrophages were actively mobile and intensively phagocytic cells. Multinucleate giant macrophages were only seen within empty egg shells. In addition to normal looking lymphocytes and plasma cells, several lymphocyte-like Sezary cells characterized by strikingly convoluted "cerebriform" nuclei were observed. Mature neutrophils and eosinophils were detected in addition to abnormal looking neutrophils; these contained numerous filamentous bundles. Fibroblasts were associated with extracellular collagen fibers and an electron-dense material. The few mast cells seen in proximity to blood vessels have a feature consistent with the onset of degranulation. Few blood platelets with active phagocytic features were among the granuloma cells.

Falciparum malaria in naturally infected human patients: ultrastructural alterations of non-parasitized red blood cells during anaemia.

Several ultrastructural alterations have been displayed by non-parasitized erythroblasts (Eb) and erythrocytes (Ec) in the peripheral blood of 28 Saudi patients who were anaemic and suffering from acute falciparum malaria (AFM). A counting system is incorporated to determine the rate of altered to normal red cells in plastic serial sections. The Eb showed for the first time conspicuous surface knobs which were previously described only for parasitized Ec, and are known to play a role in their adhesion to vascular endothelial cells. The Ec displayed a bizarre contour and ragged appearance produced by the abundance of cytoplasmic processes. Such cells were similar to erythrocytic ropalocytes seen in haematological diseases associated with anaemia. The Ec also possessed autolysosome-like vacuoles containing rosette forms of alpha-glycogen-like particles (GLP) while smaller beta-GLP were dispersed in the cytoplasm. Ultrastructural alterations of these cells were suggested to be due to dyserythropoiesis and ineffective erythropoiesis, which were in turn attributed to an unbalance in metabolism as they were being overproduced in response to infection. Numerous haemoglobin-like particles (Hg) were being liberated through the erythrocytes plasma membranes indicating severe haemolysis which is considered to be one of the major factors in producing anaemia during malarial infection. This study showed tat anaemia is common in patients with AFM which is usually associated with structural alterations of non-parasitized immature and mature red blood cells (RBC). In addition, the rate of abnormal RBC correlates with the degree of parasitaemia. Moreover, old patients showed a lower degree of parasitaemia than young patients, possibly due to a less mature immune system in the later.(ABSTRACT TRUNCATED AT 250 WORDS)

Falciparum malaria in naturally infected human patients: II. Ultrastructural alterations to erythrocytes infected with asexual forms.

Ultrastructural alterations of human erythrocytes infected with asexual forms of Plasmodium falciparum were studied in naturally infected Saudi patients. These included surface knobs and nodules as well as invaginations associated with cytoplasmic vesicles observed in erythrocytes infected with asexual forms of the parasites. Such nodules and surface invaginations have been previously described only in erythrocytes infected with P. ovale and P. vivax, respectively. Within the cytoplasm of infected erythrocytes were membrane-bound clefts, similar to those that appear to be a common characteristic in all red cells infected with malaria parasites. Vacuolations were often seen in the peripheral cytoplasm and may represent hemolyzed areas. Collapsed cells with an internal-lucent interior and surrounded by an irregularly folded membrane may represent completely hemolyzed erythrocytes.

Falciparum malaria in naturally infected human patients: I. Ultrastructural differences between malaria pigments in intraerythrocytic asexual and sexual forms.

Venous blood samples were taken from patients naturally infected with the human malaria parasite Plasmodium falciparum. Two types of malaria pigment (MP) particles have been demonstrated in intraerythrocytic asexual forms (trophozoites and schizonts), while a single type was detected in gametocytes. Type I MP particles, found in both asexual and sexual forms, are electron-dense. It is suggested that these are proteinaceous and may be intermediate, utilizable metabolic products that serve as a food reserve during development of the parasite in the human host and also during the growth cycle of the sexual form in the mosquito. In asexual forms, type I particles occur within food vacuoles (FV) containing semidigested hemoglobin (Hg), while they are unenveloped in the cytoplasm of the sexual forms. Type II MP particles, found in electron-lucent residual bodies, are crystalloid and of low electron density. It is suggested that these are the final, waste product of Hg digestion in the asexual forms.

Falciparum malaria in naturally infected human patients: IV--Ultrastructural changes in peripheral white blood cells.

Ultrastructure of white blood cells (WBC) were studied in peripheral venous blood from Saudi patients with acute falciparum malaria (AFM) and compared with their counterparts in same patients 2 weeks after chloroquine treatment and full recovery. A counting system was incorporated to determine the rate of abnormal to normal cell type in plastic thick sections during the course of the disease. Neutrophilia, monocytosis, eosinopenia and lymphocytosis were associated with various ultrastructural abnormalities including: (1) Knobby phagocytic polymorphonuclear neutrophils (PMN) and promyelocytes, and PMN with highly vacuolated cytoplasm. (2) Irregularly outlined electron-dense nuclei in non-functional monocytes. (3) Unusual distribution of nuclear chromatin in resting B-lymphocytes, while others possess highly vacuolated cytoplasm and knobby surfaces. (4) Absence of granules in granular lymphocytes containing the known diagnostic paratubular crystalline arrays. (5) Plasmablasts containing electron-dense granules and swollen mitochondria. These abnormalities were suggested to be due to the high level of parasitaemia producing some toxic soluble products. They may also be attributed to alteration of bone marrow macrophages as a sequence of their interaction with soluble parasite products or their phagocytic parasitized red cells and debris released during the rupture of schizonts. This study showed that the number of abnormal WBC increases in patients with high level of parasitaemia; plasmablasts have the lowest rate of abnormalities, while monocytes have the highest; old patients present with lower degree of parasitaemia than young patients due to a less mature immune system; and the AFM may have independent effects on the structure of human WBC.

Human bilharzial ureters. II. Cellular dynamic against deposited eggs.

The cellular dynamic against deposited Schistosoma haematobium eggs was studied in the submucosa and muscularis of the lower ureteral segments of Saudi patients with chronic urinary schistosomiasis. This dynamic activity was greatly affected by the damaged phase of the egg embryo. Freshly deposited eggs with "healthy" embryos were entirely surrounded by long cytoplasmic extensions of fibroblasts. Eggs with partially damaged embryos were surrounded by plasma cells which were focally adhered to spines of egg-shells and releasing their granular contents over their surface. Eggs with "dead" embryos, or empty egg-shells, were surrounded by actively mobile macrophages possessing numerous lysosomes, phagocytic vacuoles, and convoluted surface projections. After "peeling" off the outer and intermediate shell layers, macrophages invaded into eggs and fused together forming multinucleate giant macrophages. This study showed that the fibroblastic extensions acted as barriers between the parasite eggs or their products, and the host tissue; the plasma cell secretion over the egg surface may be involved in the migration of macrophages towards deposited eggs; and macrophages were the only dynamic cells responsible for the egg-shell invasion possibly for elimination.