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Biomedical subjects

M M Ibrahim

Publications and source records attributed to M M Ibrahim.

At least 37 records · Page 2Linked to original sources

Impact of severity of coronary artery stenosis and the collateral circulation on the functional outcome of dyssynergic myocardium after revascularization in patients with healed myocardial infarction and chronic left ventricular dysfunction.

The aim of this study was to assess the influence of the severity of coronary artery stenosis and the grade of collateral circulation on myocardial viability in patients with chronic left ventricular (LV) dysfunction undergoing coronary artery bypass grafting. Forty patients (age 59 +/- 8 years) with old myocardial infarction were studied by dobutamine stress echocardiography (DSE) before coronary artery bypass grafting. LV function was assessed using a 16-segment, 5-grade score model. Viability and functional recovery were respectively defined as a reduction in wall motion score > or = 1 at low-dose DSE and at follow-up echocardiograms obtained 3 months after surgery. There were 56 stenotic coronary arteries subtending severely dyssynergic myocardial segments, of which 38 were occluded. Among 186 severely dyssynergic segments, functional recovery occurred in 42 (23%). There was no significant difference between myocordial regions with patent or occluded coronary arteries with respect to prevalence of viability or functional recovery and percentage of viable or recovered segments relative to the total number of dyssynergic segments. In patients with total occlusion, these parameters were not different between regions with different collateral grades. Sensitivity, specificity, and accuracy of low-dose DSE for prediction of regional functional recovery were 71%, 90%, and 86%, respectively. It is concluded that in patients with chronic LV dysfunction, the presence of total occlusion of coronary arteries supplying severely dyssynergic regions does not imply a lower prevalence or extent of functional recovery after revascularization, regardless of the grade of angiographically visualized collaterals. Low-dose DSE can identify myocardial regions with a high probability of functional improvement after revascularization regardless of the severity of underlying coronary stenosis or collateralization of the involved coronary vessel.

Collateral Circulation↗

Comparison of dobutamine stress echocardiography and 99m-technetium sestamibi SPECT myocardial perfusion scintigraphy for predicting extent of coronary artery disease in patients with healed myocardial infarction.

This study compares the value of dobutamine stress echocardiography and 99m-technetium methoxyisobutyl-isonitrile (MIBI) single-photon emission computed tomography (SPECT) in the assessment of extent and location of coronary narrowing in patients with healed myocardial infarction. Dobutamine (up to 40 microg/kg/ min)-atropine (up to 1 mg) stress echocardiography (DSE) in conjunction with MIBI SPECT was performed in 72 patients (52 men, mean age 57 +/- 11 years) with healed myocardial infarction referred for evaluation of myocardial ischemia. Ischemia was defined as new or worsened wall motion abnormalities at DSE and reversible perfusion defects at MIBI SPECT. Significant stenosis (> or = 50% luminal diameter stenosis) of the infarct-related artery was detected in 45 patients and of other coronary arteries in 22 patients. Sensitivity and specificity of remote ischemia for diagnosis of remote coronary stenosis were 68% (95% confidence interval [CI] 57 to 80) and 93% (CI 86 to 99) for DSE, and 64% (CI 52 to 76), and 90% (CI 83 to 98) for MIBI SPECT, respectively. The positive predictive value and specificity of peri-infarction ischemia for the diagnosis of infarct-related artery stenosis were 89% (CI 81 to 97) and 82% (CI 73 to 92) for DSE, and 87% (CI 79 to 95) and 82% (CI 73 to 92) for SPECT, respectively. The agreement between both techniques was higher for the diagnosis of remote than peri-infarction ischemia (84% vs 66%, p = 0.02). It is concluded that in patients with myocardial infarction undergoing dobutamine stress testing, both echocardiography and MIBI SPECT are clinically useful methods for the diagnosis of remote and infarct-related coronary artery stenosis.

Aged↗

Hypertension surveys in the developing world. Lessons from the Egyptian National Hypertension Project (NHP).

Accurate national estimates of the prevalence of hypertension in developing countries are lacking. Inadequate funds, inexperience and lack of infrastructure are also important barriers to hypertension research. The aim of this review is to help investigators from the developing countries, with limited resources, to design and conduct national hypertension surveys. The information is mostly based on the experience gained during the Egyptian National Hypertension Project (NHP) which can serve as a model for similar surveys elsewhere. The review addresses a number of important questions: (1) Why conduct a national hypertension survey in a developing country; (2) What kind of data are needed; (3) Where to start and how to raise funds; (4) Who will carry out the survey; (5) How to design your sample and where to survey; (6) How to organize and perform field operations; (7) How to collect accurate data and do quality control measures; and (8) How to handle the data?

Developing Countries↗

Dobutamine 99Tcm-MIBI SPET myocardial perfusion scintigraphy in the prediction of restenosis after percutaneous transluminal coronary angioplasty in patients unable to perform an exercise stress test.

After successful percutaneous transluminal coronary angioplasty (PTCA), restenosis occurs in a relatively high proportion of patients. Exercise thallium scintigraphy is a useful method for the detection of restenosis. In patients unable to exercise, dobutamine perfusion scintigraphy may represent a feasible alternative. However, its diagnostic accuracy in this clinical setting has not been evaluated. We studied 40 patients (29 males, 11 females) aged 57 +/- 9 years, at a mean of 185 +/- 80 days after successful PTCA with a high-dose dobutamine (up to 40 micrograms kg-1 min-1) stress test, in conjunction with 99Tcm-methoxyisobutyl isonitrile (99Tcm-MIBI) single photon emission tomography (SPET). Significant restenosis was defined as > or = 50% luminal diameter stenosis of a coronary segment with previous PTCA and was predicted on the basis of the occurrence of reversible perfusion defects in the corresponding territories. Reversible perfusion defects occurred in 20 of 29 arteries with and in 4 of 17 arteries without restenosis. The sensitivity of dobutamine MIBI for the detection of restenosis in arteries with previous PTCA was 69% (CI = 56-82), the specificity 76% (CI = 64-89), the positive predictive value 83% (CI = 73-94), the negative predictive value 59% (CI = 45-73) and accuracy 72% (CI = 59-85). The overall sensitivity of 99Tcm-MIBI SPET for the diagnosis of significant coronary stenosis (including arteries without previous PTCA) on a patient basis was 79% (CI = 67-92), the specificity 82% (CI = 70-94) and accuracy 80% (CI = 68-92). The sensitivity of 99Tcm-MIBI SPET was significantly higher than that of electrocardiography (79 vs 38%, P < 0.005). It is concluded that dobutamine 99Tcm-MIBI SPET is a useful method for the detection of restenosis after PTCA in patients unable to perform an exercise stress test.

Adult↗

Relation between ST segment elevation during dobutamine stress test and myocardial viability after a recent myocardial infarction.

OBJECTIVE: To assess the relation between ST segment elevation during the dobutamine stress test and late improvement of function after acute Q wave myocardial infarction. PATIENTS AND DESIGN: 70 patients were studied a mean (SD) 8 (3) days after acute myocardial infarction with high dose dobutamine-atropine stress echocardiography and a follow up echocardiogram at 85 (10) days. A score model based on 16 segments and four grades was used to assess left ventricular function. Functional improvement was defined as a reduction of wall motion score > or = 1 in > or = 1 segments at follow up. INTERVENTION: Myocardial revascularisation was performed in 23 patients (33%) before follow up studies. RESULTS: ST segment elevation occurred in 40 patients (57%). Late functional improvement occurred in 35 patients (50%). Functional improvement was more common in patients with ST segment elevation (68% v 30%, P < 0.005) and they had a higher mean (SD) number of improved segments at follow up (1.9 (2.2) v 0.5 (1.1), P < 0.005). The wall motion score index decreased between baseline and follow up in patients with ST segment elevation (1.54 (0.50) v 1.48 (0.43), P < 0.05) but not in patients without ST segment elevation (1.39 (0.60) v 1.45 (0.47)). The accuracy of ST segment elevation for the prediction of functional improvement was similar to that of low dose dobutamine echocardiography in patients with anterior infarction (80% v 83%) and in patients who underwent revascularisation (78% v 83% respectively). CONCLUSION: In patients with a recent Q wave myocardial infarction, dobutamine-induced ST segment elevation is a valuable marker of myocardial viability particularly when the test is performed without or with suboptimal echocardiographic imaging.

Cardiotonic Agents↗

Safety and feasibility of dobutamine-atropine stress testing in hypertensive patients.

Dobutamine stress testing is increasingly used for the diagnosis and functional evaluation of coronary artery disease. The aim of this study was to assess the hemodynamic profile, safety, and feasibility of dobutamine stress testing in hypertensive patients. Dobutamine (up to 40 micrograms/kg per minute)-atropine (up to 1 mg) stress echocardiography was performed for the detection of myocardial ischemia in 1164 patients with limited exercise capacity (age, 60 +/- 12 years; 761 men); 446 patients were known to have hypertension. The test was considered feasible when 85% of the maximal heart rate and/or an ischemic end point (new or worsened wall motion abnormalities, ST segment depression, or angina) was achieved. No myocardial infarction or death occurred during the test. Dobutamine induced a significant increase of heart rate in patients with and without hypertension (59 +/- 25 and 63 +/- 23 beats per minute, respectively). Peak rate pressure product was similar in patients with and without hypertension (18,566 +/- 4584 and 18,230 +/- 4508). Hypotension (systolic pressure drop > 40 mm Hg) during the test was more frequent in hypertensive patients (7% versus 4% in normotensive, P < .05). Independent predictors of hypotension were baseline systolic pressure greater than 140 mm Hg (odds ratio, 6.9; 95% confidence interval, 3.4 to 14), older age (odds ratio, 1.04; 95% confidence interval, 1.01 to 1.07), and medication with calcium channel blockers (odds ratio, 1.8; 95% confidence interval, 1.1 to 3.5). The prevalence of ventricular tachycardia was similar (4.1%) in both groups. Episodes of 10 beats or more (0.06% of patients) were terminated promptly by intravenous metoprolol administration. Dobutamine stress testing was considered feasible in 91% of patients with and 92% of patients without hypertension. Dobutamine-atropine stress echocardiography is a safe and feasible method for the assessment of hypertensive patients referred for evaluation of myocardial ischemia. Despite the higher prevalence of dobutamine-induced hypotension in these patients, the feasibility of the test is comparable to that in individuals without hypertension.

Aged↗

Teratogen-induced eye defects mediated by p53-dependent apoptosis.

BACKGROUND: Many birth defects are believed to involve gene-environment interactions, although the mechanisms involved are poorly understood. Apoptosis is a common effect of many kinds of environmental stresses on the developing embryo; therefore, mechanisms of teratogenesis may be approached within the context of the cell death program. The p53 tumor suppressor gene encodes a transcription factor which functions as a critical regulator of apoptosis in response to environmental stress. RESULTS: To investigate the relationship between p53-dependent apoptosis and teratogenesis, we subjected day 8 mouse embryos with different p53 gene backgrounds to a genotoxic stress, 2-chloro-2'-deoxyadenosine. Treatment rapidly stimulated nuclear p53 accumulation and triggered apoptosis in some (head-fold) but not other (primitive heart) developing structures. Induced cell death was p53 gene-dose dependent, as shown by the intermediate sensitivity of 4-5 somite stage embryos bearing only a single effective p53 allele and the lack of sensitivity of p53-null mutants. Abnormal development was manifested as eye defects by day 11, particularly lens agenesis. Overall the incidences of these defects at term were 73.3% for p53 wild-type fetuses, 52.5% for heterozygous mutants, and 2.2% for p53-null mutants. Statistical analysis indicated that the interaction between teratogen and genotype was highly significant (P < or = 0.001) for cell death on day 8 and eye defects on day 17. CONCLUSIONS: We conclude that teratogen induction of p53-dependent apoptosis in the developing embryo is positively coupled to the determination of congenital eye defects.

Abnormalities, Drug-Induced↗

Hemodynamic and 24-h blood pressure profile of amlodipine monotherapy.

OBJECTIVES: To test the therapeutic efficacy, hemodynamic profile, changes in arterial compliance, left ventricular mass and side effects of amlodipine monotherapy in hypertensive Egyptians. BACKGROUND: Amlodipine is a dihydropyridine calcium antagonist with prolonged duration of action. Its hemodynamic and hypotensive effects were not reported in hypertensive Egyptians. Hypertension is a major health problem in Egypt. Racial differences in hypotensive efficacy of some drugs have been described. METHODS: Thirty-two hypertensive patients in stages I and II WHO were recruited from a hypertension clinic. Following 2-4 weeks placebo period 23 patients satisfied inclusion criteria of DBP 95-115 mm Hg. Active amlodipine therapy 5-10 mg was given once daily. Office BP was measured at monthly intervals for 3 months. Ambulatory 24-h blood pressure (ABP) and echo-Doppler studies were performed at the end of placebo and after amlodipine therapy. RESULTS: Twenty patients completed the 3 months active treatment period, their age ranged from 30-63 years; 13 were males, body mass index (BMI) was 31 +/- 14 kg/m2 (mean +/- s.d.). Office systolic (S) BP decreased from 152 +/- 14 to 133 +/- 8 mm Hg, diastolic (D) BP from 104 +/- 6 to 89 +/- 8 mm Hg, BP was normalised ( < 140/90 mm Hg) in 13 patients. Heart rate did not change. ABP 24 h, day-time, night time and early morning readings decreased significantly. Amlodipine attenuated SBP rises ( > 140 mm Hg) from 62% to 28% (P < 0.001) and DBP ( > 90 mm Hg) from 73% to 46% (P < 0.001). Cardiac index and left ventricle (LV) functional shortening did not change while systemic vascular resistance decreased from 35 to 29.8 units (P < 0.001). LV mass index decreased from 101 to 96 gm/m2 (NS) and arterial compliance increased from 0.97 to 0.99 ml/mm Hg (NS). Oedema of lower limbs developed in six patients and was the only side effect. CONCLUSION: Amlodipine effectively lowered BP when given as monotherapy to hypertensive Egyptians. It did not influence heart rate, cardiac index or myocardial contractility. Change in LV mass and arterial compliance were not significant.

Adult↗

The Egyptian National Hypertension Project (NHP): preliminary results.

The prevalence of hypertension (HTN), its cardiovascular complications, the role of environmental and demographic factors were examined in a cross-sectional national survey of 7915 individuals--25 years and older--in 21 sampling locations in six Egyptian governorates. Sample had a stratified, multistage, probability design. The weighted national estimate of HTN (SBP > or = 140 mmHg, DBP > or = 90 mmHg or on medications) was 26%. Hypertension was more prevalent in the following groups: unemployed (49.7% vs 25.3%), socially isolated--living alone (59.7% vs 29.9%), low educated 34.1% vs 24.2%) and in the obese (BMI > 31 kg/m2: 39.8% vs 26.5%). Hypertension prevalence increased progressively with age and was more prevalent in urban than rural areas.

Adult↗

Dobutamine thallium-201 SPECT imaging for assessment of peri-infarction and remote myocardial ischemia.

UNLABELLED: This study assessed the value of dobutamine 201Tl scintigraphy for detecting significant disease of infarct-related and remote coronary arteries in myocardial infarction patients. METHODS: Dobutamine (up to 40 micrograms/kg/min)/atropine (up to 1 mg) stress test in conjunction with stress-reinjection 200Tl SPECT was performed in 71 symptomatic patients with left ventricular dysfunction > 3 mo after myocardial infarction. Ischemia was defined as reversible perfusion defects. RESULTS: Significant coronary artery stenosis (> or = 50% luminal diameter stenosis) was detected in all patients. Sensitivity, specificity and accuracy of regional ischemia for the diagnosis of remote coronary artery stenosis were 74% (95% Cl 63-86), 80% (Cl 70-90) and 76% (Cl 65-87), respectively. Those for infarct-related artery stenosis were 71% (Cl 60-81), 83% (Cl 75-92) and 72% (Cl 61-82), respectively. Ischemic perfusion score was higher in patients with multiversus single-vessel disease (1056 +/- 1021 versus 423 +/- 633, p < 0.01). CONCLUSION: Dobutamine thallium scintigraphy is valuable for assessing the extent of coronary stenosis on the basis of reversible hypoperfusion in symptomatic patients late after myocardial infarction.

Atropine↗

Child mortality in a collapsing African society.

A cohort study of mortality among under-5-year-olds was carried out in two Somali villages in 1987-89, a period of economic and political collapse in the rural parts of the country. Analysed was the relative importance of the social characteristics for under-5-year-old mortality against a background of deteriorating political and economic conditions. Mortality increased among under-5-year-olds from 1987 (211 per 1000) to 1988 (323 per 1000) to 1989 (414 per 1000). The mortality risk was more pronounced for boys than girls and was more so for infants than children aged 1-4 years. The major signs prior to death were respiratory infections, diarrhoeal diseases, fever/malaria and tetanus in the neonatal period. Over the 3-year study period mortality rates for diarrhoeal diseases increased significantly, while those for respiratory infections and diseases preventable by immunization increased more slowly. The increasing trend in under-5-year-old mortality was more pronounced in instances when the mother derived her major income from sources other than farming and in larger households.

Child, Preschool↗

Mutagenesis of human adenosine deaminase to active forms that partially resist inhibition by pentostatin.

Human adenosine deaminase (ADA) cDNA was randomly mutagenized in vitro and bacterial transformants were selected for resistance to the potent enzyme inhibitor, pentostatin (dCF). Cells transformed with mutant plasmids dCF-R2 and dCF-R6 were able to grow in the presence of 10(-6) M dCF, whereas 10(-11) M dCF blocked growth of cells complemented with wild-type ADA. DNA sequence analysis revealed double G/A conversions mutating Lys11 and Gln255 in dCF-R2, and Gly 31 and Glu 99 in dCF-R6, to different amino acids. Located far from the enzyme active site, these substitutions did not greatly affect the Km or Ki of the enzyme but were predicted to destabilize interactions within the enzyme structure. Mutants such as these may be useful to analysis of the stereology of inhibitor binding to ADA and toxicity of dCF.

Adenosine Deaminase↗

The Egyptian National Hypertension Project (NHP). Design and rationale. The NHP Investigative Team.

Hypertension and its complications appear to be increasingly common in Egypt. The National Hypertension Project (NHP) is a collaborative Egyptian-American effort with the following objectives: (1) to determine the prevalence of hypertension and blood pressure-related preclinical and clinical complications in Egyptian adults, (2) to identify environmental factors associated with high blood pressure, and (3) to build an infrastructure for research and education in cardiovascular disease prevention in Egypt. The NHP surveys were conducted in six of Egypt's 26 governorates, representing distinct geographic regions. In each of these six governorates, a probability sample of 600 households was surveyed. NHP was conducted in two phases. In phase I a team of specially trained physicians conducted household surveys in which all adult residents (age > or = 25 years) were screened for hypertension. In phase II hypertensive adults identified in phase I (ie, those with systolic pressure > or = 140 mm Hg and/or diastolic pressure > or = 90 mm Hg and/or those receiving antihypertensive drug therapy) along with a randomly selected sample of normotensive control subjects were asked to participate in a more extensive evaluation. This included a detailed history and clinical examination, an electrocardiogram, an echocardiogram, laboratory studies, and skin color reflectance (on a subsample). As the first systematic, national survey of hypertension and its complications in an Arab country, NHP should provide data of great interest to the scientific, provider, and public health communities.

Adult↗

Hypertension prevalence, awareness, treatment, and control in Egypt. Results from the Egyptian National Hypertension Project (NHP). NHP Investigative Team.

This report from the Egyptian National Hypertension Project presents national estimates of the prevalence of hypertension and the extent to which high blood pressure is being detected, treated with medications, and controlled in the Egyptian population. The results are based on findings from a national probability survey of adults > or = 25 years of age conducted in six Egyptian governorates. With the use of a stratified multistage probability design, 6733 people (85% response rate) were examined. Hypertension was defined as systolic pressure > or = 140 mm Hg, and/or diastolic pressure > or = 90 mm Hg, and/or reported treatment with one or more antihypertensive medications. Overall, the estimated prevalence of hypertension in Egypt was 26.3%. Hypertension prevalence increased progressively with age, from 7.8% in 25- to 34-year-olds to 56.6% in those 75 years or older. Hypertension was slightly more common in women than in men (26.9% versus 25.7%, respectively). Overall, 37.5% of hypertensive individuals were aware that they had high blood pressure, 23.9% were being treated with antihypertensive medications, and 8.0% were under control (systolic pressure < 140 mm Hg and diastolic pressure < 90 mm Hg). Hypertension prevalence as well as awareness, treatment, and control rates varied by region, with Cairo having the highest prevalence (31.0%) and the Coastal Region having the highest control rate (15.9%). Rates of awareness, treatment, and control tended to be lowest in areas of lower socioeconomic status. Our results indicate that hypertension is highly prevalent in Egypt and that the rates of hypertension is awareness, treatment, and control are relatively low.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Bcl-2 relieves deoxyadenylate stress and suppresses apoptosis in pre-B leukemia cells.

The influence of bcl-2 activity on 2'-deoxyadenosine-induced apoptosis was investigated in 697 human pre-B leukemia cells stably transfected with expression plasmid pHeBo-BCL-2alpha (697/BCL2 cells). Apoptosis was induced by the 2'-deoxyadenosine analogue, 2-chloro-2'-deoxyadenosine (Cl-dA), with the concentration for apoptosis in one-half of the cells at 24 hours (LD(50)) being 10 microM for 697 cells and 120 microM for 697/Bcl 2 cells. There was a strong positive correlation between Cl-dATP levels and apoptotic index (coefficient of determination, r(2)=0.95; P=0.027). When 697 cell and 697/Bcl 2 cell lines were treated with 5 microM Cl-dA, Cl-dATP did not significantly accumulate in the latter. The Cl-dATP/dATP ratio was 0.03 in Cl-dA treated 697/Bcl 2 cells but nearly 6 in treated 697 cells. Bcl 2 overproduction also suppressed the accumulation of dAMP, dADP and dATP in cells exposed to 2'-deoxyadenosine in the presence of pentostatin to abrogate the pronounced inversion of ATP/dATP pools associated with 2'-deoxyadenosine exposure. These results suggest that one consequence of bcl-2 activity is suppression of 2'-deoxyadenosine phosphorylation and elevation in the apoptotic target cells. Relief from deoxyadenylate stress imbalances implies a novel upstream site of bcl-2 activity.

Journal Article↗

Diarrhoea among children in rural Somalia. Maternal perceptions, management and mortality.

Diarrhoea was the second most common symptom of disease in a longitudinal study of 431 children under 5 years of age in rural Somalia. Most mothers perceived diarrhoea as a condition in which oral rehydration therapy (ORT) and feeding were logical parts of its management. During 1 year of observation, ORT was used in the household in one-third of the episodes of diarrhoea, mostly by non-farming, young and literate mothers. Infants were treated more often than older children, as were also children in smaller households. In a 3-year demographic surveillance in the same area (1219 person years), the under-5 mortality from diarrhoea in children of literature and illiterate mothers was 43 per 1000 (95% CI 0-84) and 93 per 1000 (95% CI 60-101), respectively. The findings suggest that the use of ORT is associated with a mother's ability to allocate time to health care and her general position in the household.

Adult↗

Rat renal interstitial bradykinin, prostaglandin E2, and cyclic guanosine 3',5'-monophosphate. Effects of altered sodium intake.

Kinins generated intrarenally probably affect renal function by altering levels of various mediators and messengers, including prostaglandin E2 (PGE2) and cyclic guanosine 3',5'-monophosphate (cGMP). Using a microdialysis technique, we monitored levels of cortical and medullary renal interstitial fluid kinins, PGE2, and cGMP after 5 days of 0.15% (low), 0.28% (normal), or 4.0% (high) sodium intake. Samples were collected from anesthetized rats (n = 5 for each diet). During normal sodium intake, renal interstitial fluid kinin, PGE2, and cGMP levels in dialysate leaving the cortex were 113 +/- 8 pg/min, 1.23 +/- 0.11 pg/min, and 0.05 +/- 0.004 pmol/min, respectively. In the fluid leaving the medulla, the levels were 93.0 +/- 17 pg/min, 2.28 +/- 0.14 pg/min, and 0.08 +/- 0.005 pmol/min, respectively. In rats consuming a low sodium diet, renal cortical interstitial fluid kinin and cortical and medullary PGE2 and cGMP appearance rates were significantly increased (P < .01). Rats consuming a high sodium diet showed renal cortical and medullary kinin levels that were decreased 100-fold (P < .01), whereas PGE2 and cGMP were increased (P < .01) compared with levels in rats with normal sodium intake. Renal interstitial fluid kinin is extremely sensitive to dietary sodium, but changes in interstitial fluid PGE2 and cGMP are not always directionally similar, suggesting different regulations of these substances in response to sodium intake.

Animals↗