COVID-19 surveillance report for Sudan, 2020 to 2021

Background

Following the World Health Organization declaration, COVID-19 was first appearance in Sudan was in March 2020. Cases were reported to the Sudan Federal Ministry of Heath through the surveillance system from different sources. This study used surveillance data from 2020 to 2021 to describe the epidemiologic patterns of COVID-19 occurrence in Sudan and provide insight for better preparedness and response.

Methods

Through a retrospective descriptive study, COVID19 cases records obtained from the national surveillance line-list in Surveillance and Information Directorate in Federal Ministry of Health. The analysis of data was done with SPSS version 21. Descriptive analysis done by frequencies and percentages, and further analysis through performing multivariate logistic regression.

Results

Out of 48,545 suspected cases tested for COVID-19 using RT-PCR, 27,453 (56.5%) tested positive with case fatality ratio of 6.5%. Higher death rate among elderly (78% > 60-year-old) and males (70.1%). From the reported cases, 53.8% showed no symptoms, while the common symptoms among symptomatic patients were; fever (26.4%), cough (19.1%), shortness of breath (16.8%) with small proportion (4.5%) reported loss of smell and taste. Specific states, Khartoum, Gezira and Red Sea showed highest prevalence. The disease peaked four times during 2020-2021, with a proposed alert threshold of 200-250 cases per week acting as an explosion point nationwide.

Conclusions

The high case fatality rate in the country requires further analysis, as well as the high proportion of asymptomatic infection. This will be ensured by improving the quality and completeness of surveillance data. A proposed threshold of 200-250 cases per week should be an alert to augment the measures of controlling the pandemic over the country, including providing enough supplies to decrease mortality.

Development of Perovskite (MACl)0.33FA0.99MA0.01Pb(I0.99Br0.01)3 Solar Cells via n-Octylammonium Iodide Surface Passivation

The influence of n-octylammonium iodide (OAI, passive layer) on the types of phases formed in a (MACl)_0.33FA_0.99MA_0.01Pb(I_0.99Br_0.01)₃ perovskite film was studied using X-ray diffraction. Using UV spectrophotometric techniques, it was determined how varied OAI additive layer ratios affected the linear and nonlinear optical characteristics of glass substrates/FTO/compact TiO₂/mesoporous TiO₂/(MACl)_0.33FA_0.99MA_0.01Pb(I_0.99Br_0.01)₃ films. All films' direct optical bandgap energies were determined to be 1.54 eV. The effects of OAI addition on the films' photoluminescence intensity and emitted colors were also investigated. For the fabricated perovskite solar cells (PSCs) without an OAI passivation layer, the corresponding power conversion efficiency (PCE), open-circuit voltage (V_OC), short-circuit current density (J_SC), and fill factor (FF) values were 18.8%, 1.02 V, 24.6 mAcm^-2, and 75%, respectively. When the concentration of OAI reached 2 mg, the maximum obtained values of PCE, V_OC, J_SC, and FF were 20.2%, 1.06 V, 24.2 mAcm^-2, and 79%, respectively. The decreased trap density and increased recombination resistance were responsible for the improvement in solar cell performance.

Evidence of pre-existing active Zika virus circulation in Sudan prior to 2012

OBJECTIVE

The purpose of this study is to provide the first evidence of Zika virus circulation (ZIK) in Sudan. Zika virus was first isolated in the Zika forest of Uganda in 1947, and in 2016, the World Health Assembly declared it a public health emergency of international concern. The discovery of Zika virus circulation in Sudan came as a secondary finding in a 2012 country-wide yellow fever prevalence study, when laboratory tests were done to exclude cross-reactions between flaviviruses. The study was cross-sectional community-based, with randomly selected participants through multi-stage cluster sampling. A sub-set of samples were tested for the Zika virus using ELISA, and the ones that demonstrated reactive results were subsequently tested by PRNT.

RESULTS

The prevalence of Zika IgG antibodies among ELISA-tested samples was 62.7% (59.4 to 66.1, 95% CI), and only one sample was found positive when tested by PRNT. This provided the first documented evidence for the pre-existing circulation of Zika virus circulation in Sudan. This evidence provides the foundation for future research in this field, and further structured studies should be conducted to determine the epidemiology and burden of the disease.

Concomitant outbreaks of yellow fever and hepatitis E virus in Darfur States, Sudan, 2012

INTRODUCTION

Yellow fever (YF) is a vector-borne disease transmitted to humans by infected Aedes mosquitoes, while hepatitis E virus (HEV) is a waterborne disease that is transmitted through the fecal-oral route. Both diseases have very close clinical presentation, namely fever, jaundice, malaise, and dark urine; they differ in severity and outcome.

METHODOLOGY

In this cross-sectional, laboratory-based study, an attempt was made to measure the correlation of concomitant YF and HEV infection in Darfur States during the previous YF outbreak in 2012.

RESULTS

Results found concomitant outbreaks of YF and HEV at the same time with very weak statistical correlation between the two infections during the outbreak period, with Cramer's V correlation 0.05 and insignificant p value of 0.86.

CONCLUSIONS

This correlation indicates that clinicians and care providers in tropical areas have to deal with clinical case definitions used for disease surveillance very carefully since prevalence of HEV infection is relatively common and this increases the possibility of misclassification and missing YF cases, particularly initial index cases, in a season or outbreak.

Evaluation of two doses of triclabendazole in treatment of patients with combined schistosomiasis and fascioliasis

To determine the safety and efficacy of 2 consecutive doses of triclabendazole (TCBZ) in the treatment of Schistosoma mansoni infection in human cases infected with both S. mansoni and Fasciola sp., we conducted a field survey involving 6314 individuals from 15 villages. The overall prevalence of schistosomiasis alone was 15.8%, of fascioliasis alone 2.2%, and of combined infection 0.7%. Treatment with 2 doses of TCBZ was given to the 49 cases with combined infection. Eight weeks after treatment, the cure rate was 96% for fascioliasis and was 32.7% for schistosomiasis. All schistosomiasis cases cured had a low intensity infection. Liver function tests done before treatment and 8 weeks after substantiate the safety of 2 doses of TCBZ given to those with combined infection. Administration of TCBZ should precede praziquantel in treatment of combined infection, however TCBZ cannot be recommended for infection with S. mansoni alone.

Ineffectiveness of myrrh-derivative Mirazid against schistosomiasis and fascioliasis in humans

The present study assessed the schistosomicidal and fasciolicidal actions of the myrrh-derivative Mirazid in an area of low schistosomiasis transmission. A total of 27 patients infected with Schistosoma mansoni and 16 with Fasciola spp. received the maximum recommended dose of Mirazid. Pretreatment egg counts in 4 Kato-Katz slides were compared with similar counts in stool samples collected 1 and 2 months after treatment. Standard procedures and quality control measures were followed. The results revealed that Mirazid used as schistosomicidal or fasciolicidal agent in the maximum recommended dose has a low cure rate and produced a negligible reduction in egg counts. Prescribing such an ineffective drug in Egypt might endanger the achievements of the schistosomiasis control strategy.

Influence of diabetes on manifestations and treatment outcome of pulmonary TB patients

OBJECTIVE

To understand the influence of diabetes on the clinical and bacteriological aspects and treatment outcome of pulmonary tuberculosis (PTB) patients.

SETTING AND DESIGN

Records of 692 consecutive smear-positive PTB patients admitted to a referral hospital in Riyadh, Saudi Arabia, were reviewed retrospectively. The characteristics of 187 patients with diabetes mellitus (PTB-DM group) were compared to 505 patients without DM (PTB group).

RESULTS

In the PTB-DM group, 65.2% of the patients had numerous acid-fast bacilli (AFB) on sputum smear examination compared to 54.1% in the control group (P = 0.008). Among new cases, PTB-DM patients had a lower prevalence of resistance to any anti-tuberculosis drug (6.4% vs. 16.0%, P = 0.007) and achieved higher sputum conversion rates at the end of 3 months of treatment (98.9% vs. 94.7%, P = 0.013). Favourable outcomes (cured/treatment completed), failure, death and default were comparable in both groups (P = 0.7005).

CONCLUSIONS

PTB-DM patients have a higher pre-treatment bacillary load, a lower prevalence of anti-tuberculosis drug resistance and achieve slightly higher sputum conversion by the end of 3 months of treatment compared to non-diabetic patients. The association of diabetes does not alter the final treatment outcome among PTB patients.

IL-10, IFN-gamma and TNF-alpha in acute and chronic human fascioliasis

The three cytokines, IL-10 (Th2 product), IFN-gamma (Th1 product) and TNF-alpha work in concert. The present work was undertaken to study the level of these cytokines during the acute and chronic stages of human fascioliasis in an attempt to assess the involvement of Th1 and Th2 cells in regulation of the immune response in this disease. Sera of twenty six Fasciola patients were obtained and divided into two groups: twelve with acute and fourteen with chronic fascioliasis, sera of a control group were studied simultaneously. During the acute stage, a significant increase was observed in IL-10, IFN-gamma as well as TNF-alpha and specific antibody level. In the chronic phase, a significant increase of IL-10 level was observed. IFN-gamma showed a lower level as compared to the acute stage but TNF-alpha was still high. Accordingly, in fascioliasis in the early phase of infection B cells, macrophages, Th1 and Th2 cells were all activated. They cooperate in overcoming the parasite and work to the benefit of the host. With time and after maturation of the evading worms, Th2 action predominates. IL-10 (Th2 cytokine) which is antagonistic to IFN-gamma (Th1 product) and consequently to TNF-alpha limits the immunopathology that may be caused by the latter.

Factors predicting persistent sputum smear positivity among pulmonary tuberculosis patients 2 months after treatment

SETTING

Studies have shown that adverse outcomes are more likely in patients showing persistent sputum positivity at the end of 2 months of anti-tuberculosis treatment.

OBJECTIVE

To identify simple clinical, microbiological or radiological factors associated with persistent sputum positivity under national programme conditions.

DESIGN

Sputum smear-positive pulmonary tuberculosis patients admitted in 2 consecutive years to a referral hospital, and who received standard short-course chemotherapy under direct observation, were reviewed retrospectively. Factors associated with persistent sputum smear positivity were analysed.

RESULTS

A total of 514 patients were available for review. Logistic regression analysis showed that age groups 41-60 years and more than 60 years, numerous bacilli on initial sputum smear examination, and presence of multiple cavitary diseases were significant factors associated with persistent sputum positivity at the end of 2 months of treatment (P < 0.0001).

CONCLUSIONS

Identification of high risk factors associated with persistent sputum positivity, such as specific age groups, numerous bacilli on initial sputum smear examination, and presence of multiple cavitary diseases, may be helpful in stratifying the patients according to the risk of adverse outcome, thus allowing greater efficiency in resource utilisation.

Influence of anti-tuberculosis drug resistance on the treatment outcome of pulmonary tuberculosis patients receiving DOTS in Riyadh, Saudi Arabia

OBJECTIVE

To determine the influence of anti-tuberculosis drug resistance existing prior to treatment on the outcome of pulmonary tuberculosis patients receiving standard short-course chemotherapy (SCC) under direct observation under national programme guidelines.

DESIGN

Treatment outcomes of sputum smear- and culture-positive pulmonary tuberculosis patients admitted consecutively from 1998 through 1999 in a referral hospital in Riyadh, Saudi Arabia, were reviewed retrospectively.

RESULTS

A total of 515 patients were reviewed; 139 patients were deported or transferred out. Treatment outcomes and follow-up for about 2 years were analysed for the remaining 376 patients. Among 315 patients with sensitive isolates, 301 achieved favourable outcome, none relapsed or failed, 10 defaulted, one died and three were lost to follow-up at 6 months. Mono-resistance to isoniazid, streptomycin or ethambutol did not influence the treatment outcome. All the 18 patients with mono-resistance to rifampicin were cured, but two relapsed later. Among 39 patients with any rifampicin resistance, 37 patients had favourable outcome and two failed treatment; three later relapsed. Among eight patients with MDR-TB, six had favourable outcome and two failed treatment; one later relapsed. Sputum smear conversion rates at the end of 3 months of treatment in patients with any rifampicin resistance or with multidrug resistance were inferior to those of patients with sensitive strains (89.8% vs. 96.3%, P = 0.016 and 80% vs. 96.3%, P = 0.008, respectively).

CONCLUSIONS

Anti-tuberculosis drug resistance existing prior to treatment, especially rifampicin and multidrug resistance, has an adverse effect on treatment outcome, even with directly observed standard SCC under national programme guidelines.

IL-1, IL-4 production and IgE levels in acute and chronic fasciolosis before and after triclabendazole treatment

IL-1 generation by mononuclear phagocytes, IL-4 production by Th2 lymphocytes and IgE levels in serum were measured in eight patients with acute fasciolosis and seven patients in the chronic stage of the disease before and after triclabendazole treatment. Results were compared with those of a control group of ten individuals. The monocytes and lymphocytes from patients with acute and chronic fasciolosis produced significantly lower levels of IL-1 and IL-4 respectively, particularly in the chronic phase of the disease, as compared to the control. A significant increase in IgE level in both acute and chronic fasciolosis was observed. The level was significantly higher in acute as compared to chronic cases. After treatment with triclabendazole IL-1, IL-4 and IgE levels moved towards the control indicating obvious improvement in the immunological responses of the patients.

Specific IgG avidity in acute and chronic human fascioliasis

The detection of IgG avidity in sera is potentially useful in the diagnosis of acute and chronic infection. We studied IgG avidity in 31 patients with fascioliasis, with the aim of evaluating the clinical application of this test to confirm the diagnosis of incubating cases and to distinguish between acute and chronic cases. Of the 31 cases, 13 were incubating and had a mean avidity index of 57.28 +/- 5.79%. The 18 chronic cases had an avidity index of 68.80 +/- 8.92%. The difference was highly significant. We conclude that IgG avidity is a reliable means of identifying the stage of fascioliasis and suggest a cut-off point of 59.90% to distinguish between acute and chronic infection.

Circulating antibodies and antigens correlate with egg counts in human fascioliasis

We explored the relationships between specific IgG antibody levels and circulating E/S antigen to intensity of Fasciola infection in the human host. Twenty patients with patent infection and six healthy individuals were enrolled in the study. Intensity of infection was determined by repeated egg counts in stools, while IgG antibodies against adult Fasciola gigantica somatic FI, FII and against E/S antigens were measured as ELISA O.D. readings. The level of circulating E/S antigens was determined by IELISA. Positivity as well as levels of antibodies and antigen correlated with infection intensity. These findings may disclose in the future a relation between morbidity in the acute phase and worm load.

Human fasciolosis: a study on the relation of infection intensity and treatment to hepatobiliary affection

Seventeen patients with established fasciolosis and ten normal controls were enrolled in the study. The Fasciola patients were divided according to infection intensity into two groups (four patients with high intensity and thirteen patients with low intensity) as assessed by egg counts coupled with ultrasonography for detection of worms in the biliary system. Aspartate and alanine aminotransferases (AST and ALT) levels were similar to those of the controls, within the accepted normal limits, before and after treatment denoting absence of hepatocellular injury. Total serum bile acids, individual bile acids: cholic acid (CA) and chenodeoxycholic acid (CDCA), gamma glutamyl transpeptidase (GGT) and serum alkaline phosphatase (SAP) were significantly higher among all patients as compared to the controls denoting a degree of cholestatic lesion in those patients. Patients with high infection intensity revealed higher parameters than those with low intensity. The difference was not significant. One month after treatment, there was a significant improvement in the cholestasis indicating parameters in all Fasciola cases compared to the pretreatment ones. This indicates the effective role of the drug on the hepatobiliary function. However, the levels were still different from the controls. In Fasciola infection, total and individual serum bile acids in conjunction with GGT and SAP evaluate the hepatobiliary status and detect any minor abnormalities especially in anicteric subjects. Studied after treatment, they can be useful indices for assessment of the improvement.

Short-term preoperative radiotherapy results in down-staging of rectal cancer: a study of 1316 patients

BACKGROUND AND PURPOSE

This study was undertaken to investigate down-staging effects after short-term, high-fractionated preoperative radiotherapy.

MATERIAL AND METHODS

The relationships between preoperative radiotherapy 25-25.5 Gy given over 5-7 days and clinical variables (sex, age, tumour level, metastatic disease, and tumour size) and the risk of lymph node metastases were examined in 1316 patients with rectal adenocarcinoma by uni-, and multivariate analyses.

RESULTS

Irradiated specimens contained smaller tumours (P < 0.00001) and nodal metastases were less common (P < 0.001). In a logistic regression model, tumour size in cm was positively related to the risk for nodal spread (odds ratio, OR = 1.14, 95% confidence limits, CL, of OR 1.08-1.22). In the same model, radiotherapy decreased the risk for nodal involvement (OR 0.73, 95% CL 0.58-0.92. This risk was particularly reduced when the time interval between start of radiotherapy and surgery equalled 10 days or more.

CONCLUSIONS

These results demonstrate a down-staging effect by a short course of preoperative radiotherapy which should be considered in the interpretation of radiotherapy trials and in the recruitment of patients for further postoperative adjuvant treatment.

Prevention of human fascioliasis: a study on the role of acids detergents and potassium permenganate in clearing salads from metacercariae

Prevention of human fascioliasis could depend on clearing of the leafy salads from the metacercariae. The present work evaluated the role of some chemicals in detaching and killing this infective stage. It was observed that washing in running water for 10 minutes detached only 50% of the metacercariae. Citric acid in the concentration of (10 ml/L) commercial vinegar (120 ml/L), liquid soap (12 ml/L) and KMnO4 (24 mg/L) detached all metacercariae after 10 minutes exposure. The use of vinegar and KMnO4 is recommended: the first is lethal to other parasites in the vegetables, the second destroyed the metacercariae. Vegetable leaves were not softened and remained fresh.

Studies of human fasciolosis in Egypt: some serum lipid parameters before and after treatment

Ten adult patients with proven fasciolosis were enrolled in the study. Serum samples were obtained before and one month after successful treatment using a single oral dose of triclabendazole. It was observed that, serum triglycerides (TG) and very low density lipoproteins (VLDL-C) increased, while serum total cholesterol, high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) exhibited a significant decrease. These changes were due to the degenerative necrotic damage of the hepatocytes. One month after treatment, the serum level of total cholesterol, HDL-C and LDL-C gained normal values, indicating recovery of the liver and restoration of its functions in cholesterol synthesis and esterification, while TG and VLDL-C were still significantly higher than control values. This might indicate that hepatic triglyceride lipase requires a longer period to return to a normal level.

Metacercarial precipitin test for diagnosis of human fascioliasis

A metacercarial precipitin test was devised for diagnosis of human fascioliasis. The sera tested were those of cases of fascioliasis (acute and chronic), of schistosomiasis and of normal healthy individuals. Metacercariae were prepared in the laboratory from naturally infected snails. Serum dilutions of 1:5 (20%) and 1:10 (10%) were incubated with metacercariae for periods of 6, 24 and 48 hours. No precipitation was observed when the sera of healthy persons were used. With sera of fascioliasis cases a precipitate was formed which increased in amount with time. It was more rapid in its formation and greater in its quantity with sera of acute fascioliasis. When incubation was prolonged a free precipitate was seen in the medium. With sera of schistosoma cases, a precipitate was observed in a few cases only; it was negligible in amount and localized to the plug area. Metacercarial precipitin is considered a simple, sensitive and specific test for diagnosis of human fascioliasis. It is recommended to use the serum in a dilution of 1:5 (20%), to give preliminary results after 6 hours incubation and to confirm 24 hours later.

Phagocytic activity of neutrophils in human fasciolosis before and after treatment

Neutrophil phagocytic function was studied in fifteen patients with chronic fasciolosis and five in the incubating phase of the disease. Results were compared with a control group. The chematactic index which is the ratio of directed to non directed migration, the (NBT) reduction test which estimates phagocytosis and the more recent and specific test the chemiluminescence which measures phagocytosis and intracellular killing were performed. The results showed that in fasciolosis chemotactic activity, NBT and chemiluminescence index were significantly increased as compared to controls. This increase was more prominent in the acute phase. In this stage, the immature parasites are in close contact with the liver tissue. With chronicity of infection, they reach the bile ducts and inflammation in the liver parenchyma subsides. At this stage a lower level of metabolites and antigens reach the tissues, while the majority pass with bile to the intestinal lumen. The indices returned to normal level after treatment of fasciolosis. This signifies disappearance of all stimuli responsible for activation of PMN phagocytes.

Evaluation of Fasciola excretory-secretory (E/S) product in diagnosis of acute human fasciolosis by IgM ELISA

Diagnosis of fasciolosis in the acute phase depends on a sensitive and accurate serological test. The present study is an evaluation of the efficacy of excretory-secretory Fasciola gigantica adult worm antigen by IgM ELISA. Thirty eight patients with acute fasciolosis and 14 in the chronic phase together with 23 patients with different parasitic infections were introduced in the study. Seventeen healthy, parasite free individuals, were served as controls. A crude excretory-secretory antigen and its fractions I and II (obtained by gel filtration chromatography on Sephadex G-200) were tested. The crude antigen revealed 100% sensitivity, 94% specificity and 98% accuracy at the cut off level of 0.3 in acute infection. It gave positive results in 77% of chronic cases. Cross reactions with Schistosoma and Toxoplasma were negligible. A significant positive correlation between IHA titres and ELISA O.D. readings was observed. Fractions I and II proved of no diagnostic significance. The test system F. gigantica E/S product by IgM ELISA is highly recommended for diagnosis of acute fasciolosis.

The effect of Ambrosia maritima (Damsissa) on the viability of Lymnaea cailliaudi; an experimental study

The present work aimed at studying the effect of Ambrosia maritima (Damsissa) on the viability of Lymnaea snails. Lymnaea snails used in these trials were acclimatized to laboratory conditions before use in the toxicity test. The snails were exposed to various concentrations (100-3000 mg/l) of dry powdered Damsissa, Ambrosia maritima was lethal to Lymnaea snails at concentration of 3000 mg/L after one day and at 100 mg/l after 14 days.

Molecular weight determination of Fasciola antigens specific for diagnosis of acute fascioliasis

Acute human fascioliasis depends in its diagnosis on detecting specific antibodies in the sera of patients. It was observed that both somatic fraction I and crude E/S products of adult Fasciola gigantica worm gave sensitive and specific results. Using IgM ELISA, the cut off O.D was 0.6 and 0.3 nm. and the accuracy was 93% and 98% for the two antigens respectively. Determination of the molecular weight of these two antigens was undertaken by SDS-PAGE. The molecular weight of the somatic fraction I ranged from 17.5 to 43.9 kd, that of the crude E/S products ranged from 12.5 to 14.7 kd. These results were compored with those of previous works performed on antigens of F. hepatica.

Studies on Lymnaea snails and their trematode parasites in Abis II village, Alexandria

Lymnaea snails in Abis II village were studied as regard their species, monthly distribution, density and infection rates in different water bodies. The trematode parasites in L. cailliaudi, the only species of Lymnaea in Abis II village were xiphidio in 40% of snails and Fasciola in 10%. Echinostome cercariae were detected from few snails outside Abis II village. The morphological characters of the different larval stages of the detected parasites were described.

Ultrasonographic findings in the gall bladder in human fascioliasis

This study included forty patients with incubating or open fascioliasis. All were subjected to repeated stool examination, serological and haematological study using IHAT in the former. Ultrasonography was done for upper abdomen stressing on gall bladder and assessing its function. Eighteen patients were diagnosed as incubating fascioliasis by positive IHAT, high eosinophilic count and negative stool examination for Fasciola eggs. No gall bladder changes could be detected by U.S. among those patients. Twenty two patients passed eggs in their stool were diagnosed as open Fasciola. Their gall bladder through U.S. revealed flukes in twelve of them. A weak gall bladder contractility was observed in 64% with open fascioliasis.

Thermal modeling of the malignant woman's breast

In this paper the conceptual three-dimensional model of the normal woman's breast presented in Osman and Afify, is developed into a detailed quantitative model of the malignant woman's breast. This model takes into consideration the effect of tumor size and location on the metabolic heat production, blood perfusion rate, and thermal contour plot of the malignant breast for each tumor size, depth, and location. Also the results of this investigation show that a hot spot in the malignant woman's breast thermal contour plot may not be directly related to an embedded tumor beneath the breast surface.

Thermal modeling of the normal woman's breast

A comprehensive thermal model of the normal woman's breast is presented. The model is developed taking into consideration metabolic heat production, tissue perfusion with capillary blood, arterial and venous blood thermal interaction and change of arterial blood temperature with position. A series of computer programs are written using a 3-dimensional finite-element technique to evaluate the surface temperature distribution of the breast. Comparison between the results obtained for the model and those from thermograms of a woman's breast are in good agreement.

A simple procedure for the isolation of pulmonary parenchyma free of major blood vessels and airways for biochemical studies

A new method of preparation of lung parenchyma free from small and medium sized airways and blood vessels is described. The lung is frozen in the inflated state and cut into thin slices to facilitate visualization and separation of large blood vessels and airways. With the aid of a special steel brush mounted on a kitchen blender most of the smaller as well as medium sized blood vessels and airways are easily shaved off and subsequently separated from the parenchyma by sieving through a 20-mesh sieve. The fall-through portion consists almost entirely of alveoli. Amino acid analysis of elastin separated from the sieved fragments is similar to lung parenchymal elastin isolated and dissected from fresh lung tissue.

Impaired angiotensin conversion and bradykinin clearance in experimental canine pulmonary emphysema

Chronic hypoxic lung diseases are associated with abnormal blood pressure regulation. Because the lung is the principal site of angiotensin conversion and because hypoxia decreases converting enzyme activity, we examined whether angiotensin converting enzyme activity was impaired in lung disease. 12 dogs received a 6 wk course of aerosolized and intratracheal papain that produced moderate panlobular emphysema. These dogs and 24 control dogs were anesthetized and sampling catheters were placed under fluoroscopic control. Angiotensin conversion was measured by a blood pressure response bioassay. Pulmonary converting enzyme activity was also assessed by infusing bradykinin (BK) and using radioimmunoassay to measure the instantaneous clearance of BK and the concentration of BK in the pulmonary artery which first produced spillover of BK into left atrial blood. Angiotensin conversion was reduced in the emphysematous dogs to 81.1% (13.2 SD) from 92% (6 SD) in the control dogs (P < 0.01). Instantaneous clearance of BK in the emphysematous dogs was only slightly reduced (93%), despite reduction in their Pao(2) to 75 mm Hg, indicating that the greatest proportion of the perfused vascular bed was exposed to alveolar Po(2) of >90 mm Hg. However, the barrier to BK passage provided by the lung, and measured by the spillover level, was reduced (1/4) to (1/2) that observed in control animals. That the defect was promptly corrected by supplemental oxygen indicates that regional pulmonary vascular converting enzyme activity had been impaired by regional alveolar hypoxia, which permitted some peptide to pass through the lungs unmetabolized. Determination of peptide metabolism in the lungs may provide a useful measure of regional alveolar hypoxia and may lead to new ways of assessing lung injury.