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Melbourne, Apr 10: Scientists have identified six drug candidates from more than 10,000 compounds that may help treat COVID-19.

The research, published in the journal Nature, tested the efficacy of approved drugs, drug candidates in clinical trials and other compounds.

"Currently there are no targeted therapeutics or effective treatment options for COVID-19," said Professor Luke Guddat from the University of Queensland in Australia.

"In order to rapidly discover lead compounds for clinical use, we initiated a programme of high-throughput drug screening, both in laboratories and also using the latest computer software to predict how different drugs bind to the virus," Guddat said.

The project targeted the main COVID-19 virus enzyme, known as the main protease or Mpro, which plays a pivotal role in mediating viral replication, the researchers said.

This makes it an attractive drug target for this virus, and as people don't naturally have this enzyme, compounds that target it are likely to have low toxicity, they said.

"We add the drugs directly to the enzyme or to cell cultures growing the virus and assess how much of each compound is required to stop the enzyme from working or to kill the virus. If the amount is small, then we have a promising compound for further studies," said Guddat.

After assaying thousands of drugs, researchers found of the six that appear to be effective in inhibiting the enzyme, one is of particular interest.

"We're particularly looking at several leads that have been subjected to clinical trials including for the prevention and treatment of various disorders such as cardiovascular diseases, arthritis, stroke, atherosclerosis and cancer," Guddat said.

Researchers said compounds that are already along the pipeline to drug discovery are preferred, as they can be further tested as antivirals at an accelerated rate compared to new drug leads that would have to go through this process from scratch.

"With continued and up-scaled efforts we are optimistic that new candidates can enter the COVID-19 drug discovery pipeline in the near future," Guddat said.

Karachi, May 25: The pilot of the Pakistan International Airlines (PIA)'s crashed plane ignored three warnings from the air traffic controllers about the aircraft's altitude and speed before the landing, saying he was satisfied and would handle the situation, according to a report on Monday.

The national flag carrier's PK-8303 tragedy on Friday, in which 97 people were killed and two miraculously survived, is one of the most catastrophic aviation disasters in the country's history.

The Airbus A-320 from Lahore to Karachi was 15 nautical miles from the Jinnah International Airport, flying at an altitude of 10,000 feet above the ground instead of 7,000 when the Air Traffic Control (ATC) issued its first warning to lower the plane's altitude, Geo News quoted an ATC report as saying.

Instead of lowering the altitude, the pilot responded by saying that he was satisfied. When only 10 nautical miles were left till the airport, the plane was at an altitude of 7,000 feet instead of 3,000 feet, it said.

The ATC issued a second warning to the pilot to lower the plane's altitude. However, the pilot responded again by stating that he was satisfied and would handle the situation, saying he was ready for landing, the report said.

The report said that the plane had enough fuel to fly for two hours and 34 minutes, while its total flying time was recorded at one hour and 33 minutes.

Pakistani investigators are trying to find out if the crash is attributable to a pilot error or a technical glitch.

According to a report prepared by the country's Civil Aviation Authority (CAA), the plane's engines had scraped the runway thrice on the pilot's first attempt to land, causing friction and sparks recorded by the experts.

When the aircraft scraped the ground on the first failed attempt at landing, the engine's oil tank and fuel pump may have been damaged and started to leak, preventing the pilot from achieving the required thrust and speed to raise the aircraft to safety, the report said.

The pilot made a decision "on his own" to undertake a "go-around" after he failed to land the first time. It was only during the go-around that the ATC was informed that landing gear was not deploying, it said.

"The pilot was directed by the air traffic controller to take the aircraft to 3,000 feet, but he managed only 1,800. When the cockpit was reminded to go for the 3,000 feet level, the first officer said 'we are trying'," the report said.

Experts said that the failure to achieve the directed height indicates that the engines were not responding. The aircraft, thereafter, tilted and crashed suddenly.

The flight crashed at the Jinnah Garden area near Model Colony in Malir on Friday afternoon, minutes before its landing in Karachi's Jinnah International Airport. Eleven people on the ground were injured.

The probe team, headed by Air Commodore Muhammad Usman Ghani, President of the Aircraft Accident and Investigation Board, is expected to submit a full report in about three months.

According to the PIA's engineering and maintenance department, the last check of the plane was done on March 21 this year and it had flown from Muscat to Lahore a day before the crash.

In the wake of the COVID-19 pandemic, the Pakistan government had allowed the limited domestic flight operations from five major airports - Islamabad, Karachi, Lahore, Peshawar and Quetta - from May 16.

After the plane tragedy, the PIA has called off its domestic operation.